NATURAL H I S T O R Y 
OF THE 
UNITED STATES. CONTRIBUTIONS 
TO 
THE NATURAL HISTORY 
OF THE 
UNITED STATES OF AMERICA. 
BY 
LOUIS AGASSIZ. 
'4m* 
FIRST MONOGRAPH. 
IN THREE PARTS. -I. ESSAY ON CLASSIFICATION.- II. NORTH AMERICAN TESTUDINATA.- 
III. EMBRYOLOGY OF THE TURTLE; WITH THIRTY-FOUR PLATES. 
VOL. I. 
BOSTON: I 
LITTLE, BROWN AND COMPANY. 
LONDON: TRUBNER & CO. 
1 857. Entered according to Act of Congress, in the year 1857, by 
LOUIS AGASSIZ, 
In the Clerk's Office of the District Court of the District of Massachusetts. 
CAMBRIDGE: 
ALLEN AND FARNHAM, PRINTERS. TO THE MEMORY 
OF 
IGNATIUS DOLLINGER, 
THE FOUNDER OF EMBRYOLOGY, WHO FIRST TAUGHT ME HOW TO TRACE THE DEVELOPMENT OF ANIMALS ; 
AND OF 
FRANCIS GALLEY GRAY, 
OF BOSTON, MY FRIEND AND ADVISER IN PLANNING TIIE PUBLICATION OF THIS WORK ; 
AND TO 
JOSIAH QUINCY, JONATHAN PHILLIPS, NATHAN APPLETON, 
DAVID SEARS, THOMAS GRAVES CARY, 
WILLIAM STORY BULLARD, JOHN ELIOT THAYER, 
JOHN AMORY LOWELL, AND STEPHEN SALISBURY, 
WHO UNITED WITH HIM IN SECURING THE MEANS FOR ENGRAVING THE PLATES, AT A TIME WHEN IT APPEARED 
DOUBTFUL WHETHER THE SUBSCRIPTION WOULD COVER THE EXPENSE OF ITS PUBLICATION, 
THIS WORK 
IS INSCRIBED WITH DEEP GRATITUDE 
BY 
THE AUTHOR. PREFACE. 
Perhaps I cannot better express my deep sense of the generosity with which my labors 
in America have been supported, than by a simple narrative of the manner in which I 
have collected the materials for the series, of which this volume is the first, and of the 
growth and progress of the plan for its publication. 
Since the time of my arrival in this country, now eleven years ago, I have lost no 
opportunity of making collections wherever my lecturing excursions led me ; and, by my 
own efforts, and by the friendly aid of persons throughout the United States, who have 
shown from the beginning a warm interest in my scientific pursuits, I have succeeded in 
bringing together an extensive museum of purely American specimens. My opportunities 
for investigation were, of course, daily increased, and at the end of eight or nine years 
I had on hand a great quantity of materials, containing the results of my studies in 
this country; but the expense attending the collection and support of so large a museum 
more than exhausted the means which I was able to devote to it, and I felt obliged to 
renounce all idea of publishing the results of my labors. I had them in tangible form, 
not with any expectation of ever seeing them in print, but in the hope that after my 
death my collections and papers would be found a useful guide for others, and might be, 
in the end, of some service to science in America. 
It is now two years since, in conversation with Mr. Francis C. Gray, of Boston, - now 
no longer living to see the result of his disinterested and generous efforts in behalf of 
science,- I mentioned to him the numerous preparations which I had made to illustrate 
the Natural History of North America, and my regret that the costliness of such works 
must prevent the publication of the materials I had collected. He entered at once into 
the matter with an energy and hopefulness which were most inspiring: spent some time in 
examining my manuscripts; and, having satisfied himself of the feasibility of their publica- 
tion, set on foot a subscription, of which he took the whole direction himself, awakening 
attention to it by personal application to his friends and acquaintances, by his own lib- VIII 
PREFACE. 
eral subscription, by letters, by articles in the journals, and by every means which the warmest 
friendship and the most genuine interest in science could suggest. He was rewarded 
beyond his utmost hope or mine, by the generous response of the public to whom he 
appealed. We had fixed upon five hundred subscribers as the number necessary, to enter 
upon the publication with safety; and we had hoped that the list might perhaps be 
increased to seven or eight hundred. At this moment it stands at twenty-five hundred : a 
support such as was never before offered to any scientific man for purely scientific ends, 
without any reference to government objects or direct practical aims, - although I believe 
no scientific investigations, however abstruse, are without practical results. My generous 
friend did not live to witness the completion of the first volume of the series, which 
without his assistance could not have appeared, but he followed with the deepest interest 
every step in its progress, to the day of his death; - he did live, however, to hear the 
echo which answered his appeal to the nation, in whose love of culture and liberality 
towards all intellectual objects he had felt so much confidence. From all the principal 
cities, and from towns and villages in the West, which a few years since did not exist; 
from California, from every corner of the United States, - came not only names, but 
proffers of assistance in the way of collections, and information respecting the distribution 
and habits of animals, which have been of the utmost assistance in the progress of the 
work. 
It has been my wish to make my part of the undertaking worthy of the interest so lib- 
erally shown by the community ; and in this I have been greatly assisted by the liberal 
views which the publishers have taken, from the beginning, with regard to its publication. 
And now, in presenting this volume to the American public, I would take occasion to 
repeat, - what has already been stated in a circular to my subscribers, - that the plan of 
the work has been enlarged, in consequence of the liberality of the subscriptions, in a 
manner which has delayed the publication for nearly a year, but which has, I believe, 
made the book more valuable. I have thus been able to double, at the least, the num- 
ber of figures upon most of the plates, and to include in the text, generalizations which 
are the results of my whole scientific life; so that this volume, - which, according to the 
original plan, was designed to be one of special descriptive Zoology, - contains, in addition 
to a description of the North American Turtles, a review of the classification of the whole 
animal kingdom. I have also endeavored to make it a text-book of reference for the 
student, in which he may find notices of all that has been accomplished in the various 
departments of Natural History alluded to, and which, I trust, young American naturalists 
will take not only as an indication of what has been done, but as an earnest of what 
remains to be done, in the fields now open to our investigation. 
In consequence of these additions, the first volume is more bulky than was intended, but 
contains no plates; while the second, in order to avoid mixing heterogeneous subjects, had PREFACE 
IX 
to be brought to a close before its size amounted to what it should be ; but in the suc- 
ceeding volumes full compensation will be made for this, and measures taken to bring 
them forward with more promptitude. 
With reference to the future progress of Zoology in this country, it is particularly 
desirable that investigators should not allow themselves to be carried away by the almost 
inexhaustible diversity of species, so as to confine their efforts to describing merely what 
is new, for however desirable it may be that all our species should be correctly named, 
described, and delineated, such labors are, in fact, only the preliminary steps towards deeper 
and more philosophical studies; and the sooner attention is turned to the mode of 
life of all our animals, to their geographical distribution, their natural affinities, their 
internal structure, their embryonic growth, and to the study of fossil remains, the sooner 
will the investigations of American naturalists contribute largely to the real advancement 
of science, and the investigators themselves acquire an independent standing among scien- 
tific men. I am well aware, while writing this, that there are already many who pursue 
the study in that truly scientific spirit which has brought Natural History to its present 
prosperous state ; my remarks, therefore, do not apply to these noble devotees of truth. 
But I know equally well, that there are too many who fancy that describing a new 
species, and hurrying to the press a hasty and mostly insufficient diagnosis, is a real 
scientific achievement. These I would warn from the deceptive path, adding, that a long 
experience has taught me that nothing was ever lost to an investigator by covering, as 
far as possible, the whole ground of any subject of inquiry; and that, though at times a 
subject may seem to have lost some of its value for being less novel, it generally gains 
tenfold in scientific importance by being presented in the fullest light of all its natural 
relations. It is chiefly this conviction which has induced me to keep to myself for so 
many years the results of my investigations in this country; and if, in the course of this 
publication, I am occasionally compelled to offer fragmentary information upon many parts 
of my subject, it is simply because the time has come with me when I must publish what 
I have been able to observe, if I would publish at all. 
Scandinavia, Germany, and France afford us striking examples of the new impulse 
science has received, in consequence of the gradual exhaustion of the field afforded them for 
descriptive Zoology. As soon as most of the species of these countries had been described, 
after Linnaeus had begun to register systematically the whole animal kingdom, those who 
were denied the opportunity of visiting foreign countries, or of receiving large supplies of 
new species from distant lands, applied themselves to the investigation of the internal 
structure of the animals already described, and to the study of their habits, their metamor- 
phoses, their embryonic growth, etc. Never did Zoology receive a more important impulse than 
at the time when German students began to trace with untiring zeal the earliest development 
of all the classes of the animal kingdom, and some Scandinavian observers pointed out the PREFACE. 
X 
wonderful phenomena of alternate generations; and, if we would not remain behind in the 
generous race now running in science, we must take good care, while we investigate our 
Fauna and describe our new species, to combine the investigation with all those considera- 
tions which give true dignity to science, and raise it above the play of the mere collector. 
I must beg my European readers to remember, that this work is written in America, 
and more especially for America ; and that the community to which it is particularly 
addressed has very different wants from those of the reading public in Europe. There is 
not a class of learned men here, distinct from the other cultivated members of the com- 
munity. On the contrary, so general is the desire for knowledge, that I expect to see my 
book read by operatives, by fishermen, by farmers, quite as extensively as by the students 
in our colleges, or by the learned professions; and it is but proper that I should endeavor 
to make myself understood by all. 
Lieber, - whose testimony cannot be questioned, as, like myself, he did not first see 
the light of day in America, - justly remarks, what is particularly true of the United 
States, " that one of the characteristic features of the nineteenth century in the great 
history of the western Caucasian race, is a yearning for knowledge and culture far more 
general than has ever existed at any previous period on the one hand, and on the other 
a readiness and corresponding desire in the votaries of knowledge to diffuse it, - to make 
the many millions share in its treasures and benefits."1 
It must not be overlooked also, that, while our scientific libraries arc still very defective, 
there is a class of elementary works upon Natural History widely circulated in Europe, and 
accompanied with numerous illustrations, which are still entirely unknown in this country. 
In most of our public libraries there are no copies of such works as Swammerdam, 
Roesel, Reaumur, Lyonet, etc., nor any thing, within the reach of the young, like those 
innumerable popular publications, such as Sturm's Fauna, the Insect Almanachs, Bertuch's 
Bilderbuch, and the neatly illustrated school-books published in Esslingen, or like the series 
of valuable treatises illustrating the Natural History of England, and the popular sea-side 
books, which, in the Old World, are to be found in the hands of every child. The only 
good book upon Insects in general, yet printed in America, is " Harris's Treatise on the 
Insects injurious to Vegetation in Massachusetts"; and that book does not contain even a 
single wood-cut. There has not yet been published a single text-book embracing the 
whole animal kingdom. This may explain the necessity I have felt of introducing fre- 
quently in my illustrations, details which, to a professional naturalist, might seem entirely 
out of place. 
I have a few words more to say respecting the first two volumes, now ready for pub- 
lication. Considering the uncertainty of human life, I have wished to bring out at once 
1 Columbia Athenaeum Lecture, by Francis Lieber, Columbia, S. C., 1856, p. 7. PREFACE. 
XI 
a work that would exemplify the nature of the investigations I have been tracing during 
the last ten years, and show what is likely to be the character of the whole series. I 
have aimed, therefore, in preparing these two volumes, to combine them in such a manner 
as that they should form a whole. The First Part contains an exposition of the general views 
I have arrived at, thus far, in my studies of Natural History. The Second Part shows 
how I have attempted to apply these results to the special study of Zoology, taking the 
order of Testudinata as an example. I believe, that, in America, where Turtles are every- 
where common and greatly diversified, a student could not make a better beginning than 
by a careful perusal of this part of my work, specimens in hand, with constant reference 
to the second chapter of the First Part. The Third Part exemplifies the bearing of Embry- 
ology upon these general questions, while it contains the fullest illustration of the embry- 
onic growth of the Testudinata. 
As stated above, I have received contributions from every part of the country, and upon 
the most diversified subjects, relating to my studies, which I shall mention in their proper 
place in the course of the publication of my work, and give to all due credit for their 
assistance. For the present, I must limit myself to returning my special thanks to those 
who have materially contributed to the preparation of the first two volumes, now about 
to be published together. 
Above all, I must mention the Smithsonian Institution, whose officers, in the true 
spirit of its founder, have largely contributed to the advancement of my researches, by 
forwarding to me for examination, not only all the specimens of Testudinata collected for 
the museum of the Institution, but also those brought to Washington by the naturalists 
of the different parties that have explored the western territories, or crossed the continent 
with the view of determining the best route for the Pacific Railroad. These specimens 
have enabled me to determine the geographical distribution of this order of Reptiles with 
a degree of precision which I could not have attained without this assistance. Besides this, 
Professor J. Henry, the liberal Secretary of the Institution, has caused special collections of 
Turtles to be made for me in those parts of the country from which I had few or no 
specimens, and Professor Baird has spared no pains to carry out these benevolent intentions. 
I have also received from Professor Baird a number of interesting specimens, which he 
himself collected during his extensive excursions. To these gentlemen, therefore, I am 
indebted in the highest degree. Other public institutions have also afforded me valuable 
assistance. In Philadelphia, I have been able to compare the specimens of the museum 
of the Academy of Natural Sciences, which contains the originals of the great work of 
Dr. Holbrook on the Reptiles of North America. The Trustees of the University of Oxford, 
in Mississippi, have intrusted to me, at the request of Dr. L. Harper, the Reptiles of the 
State Survey for examination; and besides these, I have received many valuable specimens 
from that State, through Prof. B. L. Wailes. Prof. Alexander Winchell has also sent me XII 
PREFACE. 
all those of the museum of the University of Ami Arbor, in Michigan; and, through the 
kindness of Professor Poey of the University of Havana, I have been able to compare 
the Turtles of the island of Cuba with those of the continent of North America. Prof. 
Jeffries Wyman has allowed me, with the same liberality, the free use of the preparations 
relating to Turtles contained in the museum of Comparative Anatomy of our University. 
I have also received valuable specimens for comparison from the museum of the Essex 
Institute, in Salem. 
Among private individuals who have largely contributed to my collection of Turtles, I 
have to mention, first, Mr. Winthrop Sargent, of Natchez. Not satisfied with collecting 
extensively the Turtles in the neighborhood of his residence, he undertook a journey 
of many hundred miles for the special purpose of securing all the species living in the 
adjoining regions, and, having completed the survey, set out with a cargo of living Tur- 
tles, and brought them safely alive to me in Cambridge, after a journey of over a thou- 
sand miles. Such devotion to the interests of science, on the part of a gentleman who 
is not himself a naturalist, deserves more than a passing notice. To him I am indebted 
for the opportunity of studying several species, alive, which have probably never been seen 
before, by any naturalist, in a fresh state. 
It would be difficult for me to convey an adequate idea of the value of all the different 
contributions I have received for this part of my work. In some instances they consisted 
perhaps of a few specimens of well-known species, but then they came from regions where 
their presence had not been ascertained before; or the specimens were so numerous as to 
afford ample opportunity to determine the range of their variations; or there were among 
them, young ones, in a state of development not before observed. Yet I may well say, 
that, however numerous have been the invoices of Turtles which I received from the differ- 
ent States, not one was superfluous ; and 1 have frequently regretted that I could not ob- 
tain more, for there are still several species, the eggs or the young of which I have not 
been able to get. 
The better to show to what extent these specimens were sufficient satisfactorily to 
determine the geographical distribution of our Turtles, 1 will enumerate them in geographi- 
cal order. From the British Provinces, my information was chiefly derived from collections 
and notices sent me by Air. M. II. Perley, of St. John, and Mr. Win. Couper, of Toronto. 
In New England, I have myself collected largely; but I have also received valuable contri- 
butions from the late Rev. Zadock Thompson, of Burlington ; from Mr. James E. Mills, 
of Bangor; from the late Dr. W. I. Burnett, of Boston; from Capt. N. Atwood, of Province- 
town; from Air. D. Henry Thoreau, of Concord; from Air. F. W. Putnam, of Salem; from 
Air. Sidney Brooks, of Harwich; from Air. Sanborn Tenney, of Auburndale; and from Air. J. 
W. P. Jenks, of Middleboro'. Messrs. Tenney and .Jenks have repeatedly sent me the Tur- 
tles of our neighborhood by hundreds. From the State of New York, I have received speci- PREFACE. 
XIII 
mens from Colonel E. Jewett, of Utica ; from Mr. Albert G. Carli, of Jericho, Long 
Island ; and from an anonymous contributor in the vicinity of Rome. Mr. A. Mayor has 
sent me those of New Jersey, with interesting remarks upon the height at which they are 
found in the Cooley Mountains. From Pennsylvania, I have received very extensive col- 
lections and highly valuable information. Among the votaries of Herpetology, I must men- 
tion, first, Major LeConte, to whom science is indebted for the first accurate account of 
the North American Testudinata in general. Next to him I am most indebted to Prof. S. 
S. Haldeman, and to Dr. E. Hallowell, for series of all the species of the State. Dr. John 
LeConte, Dr. Wm. Darlington, and Dr. E. Michener have also sent me valuable specimens 
and notices; and to Dr. J. Leidy I owe the communication of the fossil remains of this older 
of Reptiles preserved in the splendid museum of the Academy of Natural Sciences. To 
Prof. Baird I am also greatly indebted for specimens from Pennsylvania and Western New 
York; but especially for a large collection of fossil bones of Turtles from the caves near 
Carlisle. 
From Ohio, I have received specimens and notices from Dr. J. P. Kirtland, of East 
Rockport; from Prof. E. B. Andrews, of Marietta; from Messrs. Jos. Clark and David H. Shaffer, 
of Cincinnati ; and from Mr. George Clark, of Toledo. From Indiana, from Prof. Richard 
Owen, of New Harmony; and Mr. F. C. Hill, of Delphi. From Illinois, from Dr. Watson, of 
Quincy ; and from Messrs. R. P. Stevens, T. H. McChesney, and Robert Kennicott. Air. Ken- 
nicott has furnished me with interesting data respecting the geographical distribution of the 
soft-shell Turtles in the tributaries of the Mississippi. From Michigan and Wisconsin, I 
have received very fine series of specimens, which have enabled me to ascertain the spe- 
cific differences that distinguish the western Chrysemys from that of the Eastern States, 
and also numerous specimens of Emys Meleagris. I am particularly indebted for these to 
Dr. P. R. Hoy, of Racine; to Mr. J. A. Lapham, of Milwaukee ; to Dr. Manly Miles, of 
Flint; and to Prof. A. Winchell, Dr. A. Sager, and Mr. D. M. Johnson, of Ann-Arbor. 
Dr. John H. Rauch, of Burlington, Iowa, has sent me large numbers of specimens from 
that State. From Missouri and Arkansas, I have received a great many specimens through 
the kindness of Dr. George Engelmann, of St. Louis; and of Mr. George Stolley, now in Texas, 
who collected very extensively for me in the western and south-western parts of Missouri, 
and later, in Arkansas and Texas. From the Territory of Minesota, Mr. James M. Bar- 
nard, of Boston, has secured for me a dozen fine specimens of an extremely rare species of 
Chrysemys, heretofore known from a single specimen preserved in the museum of the Acad- 
emy of Philadelphia, and supposed to have been found in Oregon. My acquaintance with 
the Testudinata of the other western territories, and with those of Delaware, Maryland, and 
Virginia, is chiefly derived from the contributions of the Smithsonian Institution, among 
which were the valuable collections of Dr. R. O. Abbott, and of Dr. C. B. Kennerley. From 
Kentucky and Tennessee, I have received specimens from Messrs. N. A. Gwyn, H. C. Tay- XIV 
PREFACE. 
lor, Prof. I. D. Lindsley, and interesting notices from Dr. Samuel Cunningham. From 
North Carolina, from Dr. J. IL Gibbon, Mr. S. T. Thayer, Dr. C. L. Hunter, Mr. W. 
C. Kerr, and Professor Baird. Mr. Henry Harrisse has lately sent me the drawing of a 
very remarkable young specimen of Ptychemys concinna with two distinct heads. 
Dr. Edward Holbrook, by his extensive works upon the subject, has rendered South 
Carolina classic ground for Herpetology ; and to him I am indebted for the largest supplies 
of the species found in that State. I have also received a variety of specimens from Dr. 
W. R. Gibbs, of Columbia, and from Mr. Barnwell, of Beaufort. From Georgia, I have re- 
ceived invaluable contributions. Dr. W. C. Daniell and Col. A. S. Jones have caused 
specimens to be collected for me all over the State, while Prof. LeConte, of Athens; 
Dr. Wm. Gesner, of Columbus ; Prof. N. A. Pratt, Jr., and Air. B. I. King, of Roswell; 
Mr. Alex. Gerhardt, of Whitfield County; and Mr. R. II. Gardiner, have sent me large 
numbers of specimens from their respective districts. The species of Alabama have also 
been furnished to me in large numbers by Dr. J. C. Nott, Col. Deas, and Air. Albert 
Stein, of Alobile ; by Air. Thos. AI. Peters, of Moulton ; and by Air. Th. P. Hatch, of Flor- 
ence. From Florida, I have received interesting specimens from Dr. L. AI. Jeffries, of Pen- 
sacola ; from Air. F. Eppes, of Tallahassee ; from Air. Theodore Lyman, of Boston ; and from 
Air. F. W. Putnam, of Salem. Numerous as these invoices were, I have received yet more 
extensive collections from Alississippi and Louisiana, through the kindness of the Rev. Dr. 
'Pho. S. Savage, of Pass Christian ; Air. W. Sargent, Prof. B. S. C. Wailes, and Ben- 
jamin Chase, of Natchez; Dr. L. Harper, of Oxford ; and Prof. R. II. Chilton, Dr. N. B. 
Benedict, Dr. B. Dowler, and Air. T. C. Copes, of New Orleans. 
From Texas, and the adjoining parts of Alexico, I have examined the rich collections 
made under the direction of Col. Emory during the boundary survey, and those secured 
by the Smithsonian Institution from the late Air. Berlandier. To the Rev. Edward Fon- 
taine, of Austin, I am indebted for valuable information respecting the habits of the large 
Snapping Turtle of the South-western States ; and to Dr. C. B. Kennerley and Air. George 
Stolley, of Williamson County, for numerous specimens. Air. C. J. Hering, of Surinam, 
has provided me with ample means to compare the species of the northern parts of South 
America with those of the United States and of Alexico. From California and the Gala- 
pagos Islands I have also received extensive collections, especially from California, through 
the kindness of Alessrs. Thomas G. Cary, Jr. and A. F. Branda, of San Francisco, who 
have sent me beautiful series of specimens of the only fresh-water Turtle found on the west- 
ern slope of the continent of North America, and also specimens of the Sea Turtles of 
the Pacific coast. I am indebted to Air. Charles Pickering for notices respecting the Tur- 
tles of Oregon ; and to Air. Patrick II. Frey, of New York, for a living specimen of the 
large Galapago Turtle. 
The notices respecting the mode of life and the distribution of our Turtles which were PREFACE. 
XV 
sent to me by the Rev. Thomas S. Savage of Pass Christian, the Rev. Edw. Fontaine of 
Austin, Mr. W. Sargent of Natchez, and Mr. Jenks of Middleboro', are among the most 
valuable of the kind I have received ; and to Mr. Jenks I am indebted for most of the 
eggs the development of which I have been able to trace. For a number of years he 
has provided me annually with many hundreds of eggs, of all our common species. I 
have also received many valuable invoices of eggs from Mr. T. W. P. Lewis, of Key 
West ; from the Hon. J. Townsend, of Edisto, in South Carolina ; from Dr. John Rauch, of 
Burlington, Iowa ; from Franklin C. Hill, of Logansport, Indiana ; from Dr. Michener, of 
Arondale, in Pennsylvania ; from Mr. Winthrop Sargent, of Natchez ; from Mr. Eppes, of 
Tallahassee ; from Dr. Nott, of Mobile ; from Prof. Baird, of the Smithsonian Institution ; 
from the late Rev. Z. Thompson, of Burlington, Vermont ; from Dr. A. Sager, of Ann- 
Arbor; from Major and Dr. LeConte, of Philadelphia ; from Dr. Hoy, of Racine ; from the 
late Dr. Burnett, of Boston ; from Mr. Sanborn Tenney, of Auburndale; and from a number 
of intelligent boys of the vicinity of Cambridge. I have myself obtained many rare eggs 
from species kept alive in my garden, and raised a large number of young Turtles. 
It may not be superfluous to state, that most of these specimens were sent alive to 
Cambridge, so that I had the amplest opportunity of studying their natural attitudes, their 
modes of moving and of eating, and sometimes the manner in which they lay their eggs. 
I have of course availed myself of these favorable circumstances to examine and compare 
the largest possible numbers of specimens of the same species, in order to determine the 
range of variations of each of them. There are many species, of which I have exam- 
ined many hundreds of specimens. I have also caused innumerable drawings of these 
specimens to be made by my tried friend, J. Burkhardt, representing their varieties of color 
and form, and their different attitudes. These drawings and sketches would fill over one 
hundred plates, and are too numerous to be published in this series ; but I shall avail 
myself of every opportunity to publish them, in the style of Plates 26 and 27. Minor 
contributions are mentioned, in their proper places, in the text. 
There is another kind of assistance, which I take great satisfaction in recording, as it 
comes from young friends and former pupils. Among them there is one, a lineal descend- 
ant of one of the great patriots of the American Revolution, whose modesty forbids 
that I should mention him by name. On hearing of my intention to publish a work on 
the Natural History of the United States, he immediately came forward with a most lib- 
eral pecuniary contribution to my undertaking. From other pupils I have derived assistance 
in the prosecution of the work itself. Mr. James E. Mills, of Bangor, (Maine,) has worked 
out for me the special characters of the families of the Testudinata; and Dr. Weinland has 
helped me in revising the anatomical characters of the order, in accordance with the prin- 
ciples laid down in the First Part of the work; while Mr. II. James Clark has assisted me 
from the beginning of my investigation of the embryology of these animals, and drawn, with XVI 
PREFACE 
untiling patience and unsurpassed accuracy, most of the microscopic illustrations which 
adorn my work. I owe it to Mr. Clark to say, that he has identified himself so thoroughly 
with my studies since he took his degree in the Lawrence Scientific School, that it would 
be difficult for me to say when I ceased to guide him in his work. But this I know 
very well, - that he is now a most trustworthy observer, fully capable of tracing for 
himself the minutest microscopic investigation, and the accuracy of his illustrations 
challenges comparison. I esteem myself happy to have been able to secure the continued 
assistance of my old friend, Mr. A. Sonrel, in drawing the zoological figures of my work. 
More than twenty years ago, he began to make illustrations for my European works ; and 
ever since he has been engaged, with short interruptions, in executing drawings for me. 
The mastery he has attained in this department, and the elegance and accuracy of his 
lithographic representations, are unsurpassed, if they are anywhere equalled. For all these 
invaluable services, it is but justice that I should make this public acknowledgment. 
As questions of omission or oversight may come up hereafter respecting the different 
topics discussed in these volumes, it is proper for me to state, that the printing of the 
text of the first volume has been completed more than ten months; indeed, the First Part 
passed through the press fifteen months ago. My object in delaying its publication was 
chiefly to await the time when I could lay before my readers a fair specimen of the 
plates, no one of which relates exclusively to the first volume. The text of the second 
volume was finished in June last. But here 1 met with another difficulty. The subject 
of this volume did not require a sufficiently large number of plates to be fully equivalent 
to that required for two volumes, when counting the plates as they now are, as simple 
plates, notwithstanding the large increase of figures crowded upon each, and it seemed inap- 
propriate to bind together plates belonging to different volumes. I shall therefore have to 
make up for this deficiency by a sufficient addition of plates to the third volume, the sub- 
ject of which naturally requires very numerous illustrations. I hope no disappointment 
will be felt, on this account, by my subscribers, for in the course pursued by the pub- 
lishers and by myself, they will readily see that we have aimed to do ('very thing in our 
power to respond to the liberality of the subscription ; and I trust the following volumes 
will afford additional evidence of this disposition. 
LOUIS AGASSIZ. 
Cambridge, October 3, 1857. LIST OF SUBSCRIBERS 
TO THIS WORK IN THE UNITED STATES. 
MAINE. 
Willard Small, Auburn. 
Bangor Mechanics' Association, Bangor. 
Bangor Mercantile Association, " 
Zina Hyde, Bath. 
James T. Patten, " 
Wm. E. Payne, " 
J. H. Rogers, " 
R. M. Chapman, Biddeford. 
Bowdoin College, Brunswick. 
R. H. Gardiner, Gardiner. 
George Merrick, Hallowell. 
J. A. Swan, Kennebunk. 
John C. Caldwell, East Machias. 
C. S. Daveis, Portland. 
Thomas A. Deblois, " 
Henry S. Edwards, " 
James L. Farmer, " 
Oliver Gerrish, " 
Abner Lowell, " 
J. M. Wood, " 
William Wood, " 
Waterville College, Waterville. 
Edwin Noyes, 11 
NEW HAMPSHIRE. 
John E. Tyler, Concord. 
James J. Thorndike, South Deerfield. 
Moses L. Morse, Dover. 
Chas. A. Tufts, " 
H. Y. Hayes, Great Falls. 
Thomas E. Hatch, Keene. 
George B. Twitchell, " 
Manchester City Library, Manchester. 
J. G. Cilley, 
Daniel Clark, " 
Charles H. Dalton, " 
E. Anderson, Milford. 
Miss E. A. Livermore, " 
J. Warren Towle, Portsmouth. 
VERMONT. 
J. S. Spalding, Barre. 
Samuel White Thayer, Jr., Burlington. 
D. W. Boutwell, Factory Point. 
Edward T. Fairbanks, St. Johnsbury. 
Erastus Fairbanks. St. Johnsbury. 
Franklin Fairbanks, " 
Horace Fairbanks, " 
Wm. Henry Thayer, Woodstock. XVIII 
LIST OF SUBSCRIBERS. 
MASSACHUSETTS. 
Amherst College Library, Amherst. 
Leander Wetherell, " 
Andover Theological Seminary, Andover. 
Edward Nye Bates, Barre. 
E. S. Wheeler, Berlin. 
Win. Endicott, Jr., Beverly. 
Benj. O. Peirce, " 
Massachusetts State Library, 3 copies, Boston. 
The Public Library, 3 copies, " 
American Acad, of Arts and Sciences, " 
Boston Athenaeum, " 
Boston Library Society, " 
Boston Society of Natural History, " 
Mercantile Li brary, " 
Mass. Charitable Mechanics' Assoc., " 
Henry W. Abbot, " 
C. Francis Adams, " 
C. Frederick Adams, " 
F. Alger, " 
Mrs. H. Allen, " 
Charles Amory, " 
William Amory, " 
Win. T. Andrews, " 
Nathan Appleton, " 
Samuel A. Appleton, " 
T. G. Appleton, " 
Wm. Appleton, " 
O. D. Ashley, " 
Edward Austin, " 
S. Austin, " 
Eben Bacon, . " 
Francis Bacon, " 
Wm. B. Bacon, " 
Richard Baker, Jr., " 
J. W. Balch, " 
Wm. A. Bangs, " 
G. M. Barnard, " 
Jas. M. Barnard, " 
S. B. Barrell, " 
Sidney Bartlett, " 
' Francis Bassett, " 
B. E. Bates, " 
George Bates, " 
Ives Gilman Bates, " 
John D. Bates, " 
Alexander Beal, " 
J. M. Beebe, Boston. 
A. E. Belknap, " 
Mrs. John Belknap, " 
S. A. Bemis, " 
George Bethune, " 
Jacob Bigelow, " 
Amos Binney, " 
S. Parkman Blake, " 
J. A. Blanchard, " 
Henry T. Blodget, " 
Wm. H. Boardman, " 
William Boott, " 
J. N. Borland, " 
Thos. T. Bouv£, " 
Henry I. Bowditch, " 
J. Ingersoll Bowditch, " 
N. I. Bowditch, " 
F. H. Bradlee, " 
J. Bowdoin Bradlee, " 
Josiah Bradlee, " 
Samuel Bradstreet, w 
Gardner Brewer, " 
E. D. Brigham, " 
M. Brimmer, " 
Gorham Brooks, " 
P. C. Brooks, 
J. W. Brown, " 
Vernon Brown, " 
Charles Browne, " 
S. H. Bullard, " 
Wm. S. Bullard, " 
B. F. Burgess, " 
Alvah A. Burrage, " 
Jas. P. Bush, " 
F. T. Bush, " 
P. Butler, Jr., " 
Henry Cabot, " 
George D. Carter, " 
George B. Cary, " 
Thomas G. Cary, " 
C. C. Chadwick, " 
Edward Chamberlain, " 
J. G. Chandler, " 
Walter Channing, " 
Theodore Chase, " 
C. F. Chickering, " XIX 
LIST OF SUBSCRIBERS 
T. E. Chickering, Boston. 
George H. Child, " 
Rufus Choate, " 
Joseph W. Clark, " 
Charles R. Codman, " 
Edward Codman, " 
W. E. Coffin, " 
Gardner Colby, " 
James C. Converse, " 
Joseph Coolidge, " 
Joseph S. Coolidge, " 
T. Jefferson Coolidge, " 
W. H. C. Copeland, " 
Joseph Cotton, " 
Alpheus Crosby, " 
Edward A. Crowninshield, " 
F. B. Crowninshield, " 
Frederic Cunningham, " 
J. A. Cunningham, " 
C. P. Curtis, " 
Francis Curtis, " 
George T. Curtis, " 
T. B. Curtis, " 
Martin G. Cushing, " 
Charles S. Cutter, " 
P. R. Dalton, 11 
F. Darracott, " 
Adolphus Davis, " 
James Davis, Jr., " 
William Dehon, " 
Franklin Dexter, " 
T. C. A. Dexter, " 
J. Dix, " 
A. Douglas, Jr., 11 
E. G. Dudley, " 
James A. Dupee, " 
Edmund Dwight, " 
J. Wiley Edmands, " 
Samuel A. Eliot, " 
Jonathan Ellis, " 
John L. Emmons, " 
N. H. Emmons, " 
Edward Everett, " 
George N. Faxon, " 
R. S. Fay, " 
Albert Fearing, " 
A. H. Fiske, 
Richard Fletcher, " 
John S. H. Fogg, " 
J. M. Forbes, " 
R. B. Forbes, Boston. 
William Foster, " 
William H. Foster, " 
N. Francis, " 
William F. Freeman, " 
N. L. Frothingham, " 
William H. Gardiner, " 
George Gardner, " 
H. J. Gardner, " 
John L. Gardner, " 
Joseph P. Gardner, " 
Benjamin F. Gibbs " 
Joseph B. Glover, " 
T. A. Goddard, " 
Ozias Goodwin, " 
B. A. Gould, " 
F. A. Gray, " 
F. C. Gray, ' " 
John C. Gray, " 
William Gray, " 
Benjamin D. Greene, " 
W. W. Greenough, <£ 
Mrs. Henry Grew, " 
Thomas Groom, " 
Benjamin Guild, il 
Edward Habich, " 
Andrew T. Hall, " 
Edwin H. Hall, " 
H. S. Hallet, 
G. G. Hammond, ££ 
Samuel Hammond, " 
Alpheus Hardy, " 
Nathaniel Harris, 11 
W. A. Harris, " 
Peter Harvey, " 
Daniel Harwood, " 
Franklin Haven, " 
George Hayward, " 
John T. Heard, " 
A. Hemenway, " 
N. H. Henchman, " 
C. H. Herman, " 
William Heywood, " 
George Higginson, " 
J. A. Higginson, " 
Richard Hildreth, " 
William Hilton, " 
A. Hollingsworth, " 
O. W. Holmes, 
N. Hooper, " XX 
LIST OF SUBSCRIBERS. 
R. C. Hooper, Boston. 
R. W. Hooper, " 
S. Hooper, " 
George Howe, " 
Jabez C. Howe, " 
S. G. Howe, " 
Osborn Howes, " 
H. H. Hunnewell, " 
John L. Hunnewell, " 
J. lasigi, " 
Henderson Inches, " 
Charles Jackson, " 
P. T. Jackson, " 
John Jeffries, 11 
John Jeffries, Jr., " 
T. A. Johnston, " 
George B. Jones, " 
Charles G. Kendall, " 
Catherine E. U. Kimball, " 
Moses Kimball, " 
Franklin King, « 
George II. Kuhn, " 
Thomas Lamb, " 
Abbott Lawrence, " 
Abbott Lawrence, Jr., " 
Amos A. Lawrence, " 
James Lawrence, " 
Samuel Lawrence, " 
William R. Lawrence, " 
Henry Lee, Jr., " 
Miss R. Lee, « 
Thomas Lee, " 
W. Raymond Lee, " 
Charles P. Lewis, " 
William R. Lewis, " 
Winslow Lewis, " 
Ezra Lincoln, " 
J. C. Lindsley, " 
James Lodge, " 
John E. Lodge, " 
Ammi C. Lombard, " 
Israel Lombard, " 
B. T. Loring, " 
Charles G. Loring, " 
F. C. Loring, " 
J. S. Lovering, " 
Augustus Lowell, " 
Francis C. Lowell, " 
John A. Lowell, " 
Arthur T. Lyman, " 
S. P. Lyman, Boston. 
Charles Manning, " 
J. B. Mansfield, " 
W. T. R. Marvin, 
William P. Mason, " 
D. R. McKay, " 
Levi B. Meriam, . " 
Charles H. Mills, ' " 
James K. Mills, " 
Thomas Minns, " 
George R. Minot, " 
William Mitchell, . " 
C. J. Morrill, " 
Frederick P. Moseley, " 
F. F. Miiller, " 
H. Newman, " 
Lyman Nichols, " 
Sereno D. Nickerson, " 
Otis Norcross, " 
Wm. C. Otis, " 
James W. Paige, " 
Robert T. Paine, " 
Isaac Parker, " 
Theodore Parker, " 
Mrs. S. Parkman, " 
William F. Parrott, " 
A. Peirce, Jr., " 
Samuel S. Peirce, " 
Thomas W. Peirce, " 
Charles C. Perkins, " 
George Perkins, " 
T. H. Perkins, " 
William Perkins, " 
Jonathan Phillips, " 
Mary Pratt, " 
Sarah P. Pratt, " 
William G. Prescott, " 
William H. Prescott, " 
John Pickering Putnam, " 
Miss Eliza Susan Quincy, " 
Josiah Quincy, " 
Curtis B. Raymond, " 
James Read, " 
B. T. Reed, " 
J. H. Reed, " 
Sampson Reed, " 
George Woods Rice, " 
George C. Richardson, " 
Henry B. Rogers, " 
J. C. Rogers, " LIST OF SUBSCRIBERS. 
XXI 
William Ropes, Boston. 
M. D. Ross, " 
B. S. Rotch, 44 
George R. Russell, 44 
Samuel H. Russell, 44 
Sanborn, Carter & Bazin, 44 
W. H. Sanford, 44 
Ignatius Sargent, 44 
L. M. Sargent, 44 
James Savage, 44 
James Scott, 44 
Benjamin Seaver, 44 
George Seaver, 44 
David Sears, 44 
George C. Shattuck, 44 
Lemuel Shattuck, 44 
G. Howland Shaw, 44 
Mrs. R. G. Shaw, 44 
William Shimmin, 44 
N. B. Shurtleff, 44 
Henry Sigourney, 44 
Mrs. M. B. Sigourney, 44 
F. Skinner, 44 
Jarvis Slade, 44 
Benj. A. Smith, 44 
Melanchthon Smith, 44 
Thomas C. Smith, 44 
S. G. Snelling, 44 
David Snow, 44 
S. T. Snow, 44 
M. M. Stanfield, 44 
J. Stearns, Jr., 44 
Charles H. Stedman, 44 
John J. Stevens, 44 
J. Thomas Stevenson, 44 
F. H. Story, 44 
F. H. Story, Jr., 44 
William D. Stratton, 44 
James Sturgis, 44 
Russell Sturgis, 44 
R. Sturgis, Jr., 44 
William Sturgis, 44 
Austin Sumner, 44 
S. W. Swett, 44 
W. B. Swett, 44 
William H. Swift, 44 
William S. Thacher, 44 
Frederick Wm. Thayer, 44 
Gideon F. Thayer, 44 
John Eliot Thayer, 44 
Nathaniel Thayer, Boston. 
William Thomas, " 
S. C. Thwing, 44 
George Ticknor, 44 
W. D. Ticknor, 44 
E. P. Tileston, 44 
George Timmins, 44 
Charles Torrey, 44 
Samuel Torrey, " 
Elmer Townsend, 44 
Enoch Train, 44 
A. Tucker, Jr., 44 
William W. Tucker, 44 
Frederic Tudor, 44 
William Underwood, " 
William J. Underwood, 44 
George P. Upham, 44 
Henry Upham, 44 
James Vila, 44 
Alexander H. Vinton, 44 
Geo. W. Wales, 44 
Thomas B. Wales, 44 
Andrew H. Ward, Jr., 44 
B. C. Ward, 44 
Samuel G. Ward, 44 
T. W. Ward, 44 
Charles E. Ware, 44 
John C. Warren, 44 
J. Mason Warren, 44 
Aaron D. Weld, " 
F. M. Weld, " 
William F. Weld, il 
Benj. S. Welles, 44 
John Welles, 
Jon. T. Wells, 44 
Thomas Wetmore, " 
David R. Whitney, 44 
Henry A. Whitney, 41 
Israel Whitney, 44 
Joseph Whitney, t 44 
Samuel Whitwell, 44 
Edward Wigglesworth, 44 
Mrs. Jane Wigglesworth, 44 
Mrs. Dr. Wigglesworth, 44 
Marshall P. Wilder, 44 
John H. Wilkins, 44 
G. Foster Williams, 44 
Matthew Wilson, 44 
Robert C. Winthrop, 44 
J. H. Wolcott, 44 XXII 
LIST OF SUBSCRIBERS. 
Marshall Conant, Bridgewater. 
Fisher A. Sprague, " 
Alexander Hichborn, N. Bridgewater. 
Thomas Aspinwall, Brookline. 
John A. Bird, " 
George Baty Blake, " 
Benjamin Bruce, " 
Samuel Cabot, " 
Theodore Lyman, " 
Thomas Parsons, " 
J. Wingate Thornton, " 
Harvard College, 2 copies, Cambridge. 
Harvard Nat. History Society, " 
William W. Alcott, " 
Charles H. Allen, " 
Isaiah Bangs, " 
J. Lincoln Bangs, " 
F. W. Bardwell, " 
John Bartlett, " 
G. L. Bennet, " 
Alanson Bigelow, " 
J. G. Blanchard, " 
James P. Brown, " 
Josiah P. Cooke, Jr., " 
Charles Deane, " 
L. M. Dornbach, " 
Samuel P. P. Fay, " 
C. C. Felton, " 
Henry R. Glover, " 
Mrs. Horatio Greenough, " 
Miss Louisa Greenough, " 
Edwin Harrison, " 
William Henshaw, " 
R. M. Hodges, " 
C. M. Hovey, " 
Gardiner G. Hubbard, " 
Charles C. Little, " 
George Livermore, " 
Isaac Livermore, " 
Henry W. Longfellow, " 
Charles Lowell, " 
John McDuffie, " 
George Meacham, " 
J. P. Melledge, " 
John A. Morris, " 
James Munroe, " 
William Newell, " 
Ichabod Nichols, " 
Charles E. Norton, " 
Michael Norton, " 
John G. Palfrey, Cambridge. 
Theophilus Parsons, " 
Mrs. William Parsons, " 
Joel Parker, " 
Benjamin Pierce, " 
Z. L. Raymond, " 
Ebenezer Richards, " 
George C. Richardson, " 
Mrs. Charles Theo. Russell, " 
Charles Sanders, " 
Jared Sparks, " 
Herbert H. Stimpson, " 
Henry Thayer, " 
James Walker, " 
C. M. Warren, 3 copies, " 
Mrs. Waterhouse, " 
E. P. Whitman, " 
J. E. Worcester, " 
Chas. Vaughn, " 
Webster Institute, Cambridgeport. 
William P. Butterfield, " 
John Livermore, " 
Joseph W. Parker, " 
Francis Gould, W. Cambridge. 
George H. Gray, " 
A. M. Gay, Charlestown. 
Charles S. Cary, Chelsea. 
H. S. Lucas, Chester Factories. 
John Wells, Chicopee. 
Bigelow Library Association, Clinton. 
Concord Town Library, Concord. 
R. Waldo Emerson, " 
Samuel Hoar, " 
Peabody Institute, South Danvers. 
Mrs. Alfred Rodman, Dedham. 
Mrs. E. J. W. Baker, Dorchester. 
Nahum Capen, " 
Increase S. Smith, " 
William D. Swan, " 
Frederick L. Ames, North Easton. 
Oakes Ames, " 
R. P. Stevens, N. Egremont. 
John A. Hawes, Fairhaven. 
Norman Easton, Fall River. 
P. B. Haughwout, " 
A. K. Slade, « 
E. Torrey, Fitchburg. 
Bradford H. Lincoln, S. Framingham. 
Charles B. Fessenden, Gloucester. 
George T. Davis, Greenfield. LIST OF SUBSCRIBERS. 
XXIII 
Theodore Leonard, Greenfield. 
Edwin Maynard, 44 
Joshua Stone, 44 
John L. Hobson, Haverhill. 
Augustine Heard, Ipswich. 
Sanborn Tenny, Lancaster. 
Pacific Mills, ■ Lawrence. 
Henry L. Chase, East Lexington. 
Middlesex Mechanics' Assoc., Lowell. 
J. G. Abbott, 44 
F. P. Appleton, 44 
Artemus L. Brooks, 44 
Sami. D. Sargent, 44 
J. B. Holder, Lynn. 
William Courtis, Marblehead. 
W. W. Ellis, Marion. 
Moses Merrill, Methuen. 
William Colegrove, Middleboro'. 
J. W. P. Jenks, 44 
William R. Peirce, 44 
W. W. Roberts, 44 
F. L. Tileston, Milton. 
O. B. Gunn, Montague. 
William Mitchell, Nantucket. 
S. Dewing, Jr., West Needham. 
New Bedford Free Pub. Lib., New Bedford. 
New Bedford Book Club, 44 
Frederick S. Allen, 44 
Gideon Allen, 44 
John A. P. Allen, 44 
Benjamin R. Almy, 44 
Charles Almy, 44 
Caleb Anthony, 44 
Elizabeth Arnold, 44 
Lehman P. Ashmead, 44 
Edward L. Baker, 44 
Lyman Bartlett, 44 
William G. Blackler, 44 
Charles T. Bonney, 44 
George A. Bourne, 44 
Jonathan Bourne, Jr., 44 
Lincoln F. Brigham, 44 
John H. Clifford, 
William C. Coffin, 44 
James B. Congdon, 44 
Henry H. Crapo, 44 
Benjamin Cummings, 44 
Joseph C. Delano, 44 
Stephen G. Driscoll, 44 
Charles C. Dunbar, 44 
Thomas D. Eliot, New Bedford. 
C. B. H. Fessenden, 44 
Edmund Gardner, 44 
Alexander Gibbs, 44 
Robert Gibbs, 44 
William Gifford, 44 
Thomas A. Greene, 44 
Joseph Grinnell, 44 
Lawrence Grinnell, 44 
William Hathaway, Jr., 44 
John Hopkins, 44 
Abraham H. Howland, 44 
Edward Howland, 44 
Edward W. Howland, 44 
George Howland, Jr., 44 
Lucy R. Howland, 44 
Matthew Howland, 44 
John Hussey, 44 
Edward C. Jones, 44 
Samuel Leonard, Jr., 44 
Thomas Mandell, 44 
Charles W. Morgan, 44 
S. Griffitts Morgan, 44 
Frederick Parker, 44 
Eben. Perry, 44 
Oliver Prescott, 44 
Charles S. Randall, 44 
Joshua Richmond, 44 
Joseph Ricketson, 44 
Joseph Ricketson, 2d, 44 
Andrew Robeson, 44 
Thomas D. Robinson, 44 
William J. Rotch, 44 
William R. Rotch, 44 
Joshua C. Stone, 44 
Jireh Swift, Jr., 44 
William C. N. Swift, 
Edmund Taber, 44 
William C. Taber, 44 
William H. Taylor, 44 
Elisha Thornton, Jr., 44 
John R. Thornton, 44 
Charles R. Tucker, 44 
Newburyport City Library, Newburyport. 
William Horton, 44 
Marianna C. Porter, 44 
Leonard Withington, 44 
Henry H. Babcock, Newton. 
Nathaniel T. Allen, West Newton. 
Henry P. Nichols, Newtonville. XXIV 
LIST OF 
SUBSCRIBERS 
J. D. Whitney, Northampton. 
F. B. Willard, Pembroke. 
Berkshire Medical College, Pittsfield. 
J. Holmes Agnew, " 
Chas. D. Mills, " 
S. Francis Shaw, Plainfield. 
Wm. T. Davis, Plymouth. 
William Parsons Lunt, Quincy. 
Reuben D. Mussey, Jr., Rockport. 
Charles T. Appleton, Roxbury. 
William C. Appleton, " 
B. E. Cotting, " 
Sami. T. Crosby, " 
Henry M. Dexter, " 
Jonathan French, " 
The Misses Lowell, " 
Henry W. Pickering, " 
George Putnam, " 
J. M. B. Reynolds, " 
John S. Sleeper, " 
Samuel H. Walley, " 
S. D. Bradford, West Roxbury. 
D. B. Hagar, " 
Thos. Motley, Jr., " 
William R. Robeson, " 
S. W. Rodman, " 
Stephen M. Weld, " 
Essex Institute, Salem. 
Pickering D. Allen, " 
Joseph Andrews, " 
Mrs. Georgianna C. Appleton, " 
John Bertram, " 
George W. Briggs, " 
R. Brookhouse, 11 
B. P. Chamberlain, " 
George Choate, " 
Benjamin Cox, Jr., " 
Francis Cox, " 
Tucker Daland, " 
Ephraim Emmerton, " 
Wm. P. Endicott, " 
Joseph E. Fisk, " 
Mrs. Elizabeth G. Gardner, w 
Henry Gardner, " 
Charles Hoffman, " 
Thomas Hunt, u 
A. Huntington, " 
William H. Jackson, " 
E. D. Kimball, " 
James Kimball, " 
John C. Lee, Salem. 
Nath'l. J. Lord, " 
Otis P. Lord, " 
Henry Melius, " 
Wm. S. Messervy, " 
David A. Neal, " 
Francis Peabody, " 
George Peabody, " 
S. E. Peabody, " 
J. W. Peele, 
W. P. Peirce, " 
J. C. Perkins, " 
S. C. Phillips, 
William Pickman, " 
W. D. Pickman, " 
Mrs. Lucy P. Robinson, " 
Richard S. Rogers, " 
Ripley Ropes, " 
S. A. Safford, " 
Mrs. Mary E. Saltonstall, " 
George T. Sanders, " 
Michael Shepard, " 
B. H. Silsbee, " 
John H. Silsbee, " 
Nath'l Silsbee, " 
Edmund Smith, " 
Gideon Tucker, " 
Richard P. Waters, " 
William D. Waters, " 
B. A. West, " 
Henry Wheatland, " 
Daniel A. White, " 
George Ashmun, Springfield. 
Edmund Baylies, Taunton. 
George A. Crocker, " 
William A. Crocker, " 
Gaius Dean, " 
J. and F. B. Dean, " 
Samuel B. King, " 
William Mason, " 
Balis Sanford, " 
A. King Williams, " 
Rumford Institute, Waltham. 
B. F. D. Adams, " 
James H. Ellison, " 
Franklin C. Hill, " 
Thomas Hill, " 
E. Hobbs, " 
Geo. Lawton, " 
Oliver S. Leland, " LIST OF SUBSCRIBERS. 
XXV 
G. W. Lyman, Waltham. 
John Roberts, " 
Arthur L. Devins, Ware. 
A. E. P. Perkins, " 
C. A. Bradley, Warren. 
James T. Austin, Watertown. 
J. P. Cushing, " 
Mrs. John Heard, " 
James H. Sargent, " 
J. H. Stickney, " 
R. O. Storrs, Webster. 
H. Hooker, WTestfield. 
A. H. Fiske, Weston. 
J. Q. Loring, " 
E. W. Champney, Woburn. 
J. P. Converse, " 
J. Cummings, Jr., " 
John G. Flagg, " 
John Flanders, " 
John R. Kimball, " 
T. S. Scales, 
A. Sonrel, " 
W. A. Stone, " 
J. B. Winn, " 
Worcester Co. Mechanics' Ass., Worcester. 
Young Men's Library Assoc., " 
Worcester Dist. Medical Soc., " 
James B. Blake, " 
Harrison Bliss, " 
A. H. Bullock, . 11 
Henry H. Chamberlain, Worcester. 
Isaac Davis, " 
Dwight Foster, " 
John Green, " 
Wm. A. Hacker, • " 
R. L. Hawes, " 
J. Nelson Jacobs, " 
F. H. Kinnicut, " 
Thos. Kinnicut, " 
Levi Lincoln, " 
Wm. S. Lincoln, " 
George E. Mann, " 
John C. Mason, " 
R. N. Meriam, " 
Wm. T. Merrifield, " 
P. L. Moen, " 
Arch'd M. Morrison, " 
Rejoice Newton, " 
Frederick William Paine, " 
Nathaniel Paine, " 
Frederick M. Peck, " 
Geo. W. Richardson, " 
Stephen Salisbury, " 
Wm. A. Smith, " 
Eli Thayer, " 
Charles Thurber, " 
Charles Washburn, " 
Emory Washburn, " 
Henry S. Washburn, " 
Ichabod Washburn, " 
RHODE ISLAND. 
Redwood Library, Newport. 
Wm. G. Breese, " 
G. H. Calvert, " 
J. Prescott Hall, " 
George Jones, " 
DeLancey Kane, " 
Edward King, " 
W. H. King, 
Wm. Beach Lawrence, " 
W. Newton Mercer, " 
James Phalen, " 
A. Robeson, Jr., " 
A. Smith, " 
Henry Tiffany, " 
W. S. Wetmore, Newport. 
Christopher Wolfe, " 
H. Allen Wright, " 
Brown University Library, Providence. 
Providence Athenaeum, " 
Philip Allen, Jr., " 
Z. Allen, " 
R. J. Arnold, • " 
Mrs. S. G. Arnold, " 
William M. Bailey, " 
John Barstow, " 
T. D. Bowen, " 
S. W. Bridgham, " 
John Carter Brown, " XXVI 
LIST OF SUBSCRIBERS 
Julia Bullock, Providence. 
William P. Bullock, " 
E. Carrington, " 
John F. Chapin, " 
W. B. Chapin, " 
B. H. Cheever, " 
Gilbert Congdon, " 
William T. Dorrence, " 
Elisha Dyer, " 
Wm. Grosvenor, " 
Isaac Hartshorn, " 
Wm. Danforth Hilton, " 
William W. Hoppin, " 
E. W. Howard, " 
Moses B. Ives, Providence. 
R. H. Ives, " 
Amasa Manton, " 
Joseph Mauran, " 
G. C. Nightingale, " 
S. Arnold Nightingale, " 
A. H. Okie, 
Daniel Paine, " 
A. V. Potter, " 
T. P. Shephard, " 
Amos D. Smith, " 
Samuel Boyd Tobey, " 
Samuel Fessenden, Valley Falls. 
CONNECTICUT. 
Edwin L. Holcolm, Granby. 
Lewis Howe, Greenwich. 
James Dixon, Hartford. 
Wesleyan University, Middletown. 
E. Francford, « 
John A. Russell, " 
Library of Yale College, New Haven. 
J. D. Dana, " 
Daniel C. Eaton, " 
Richard S. Fellows, " 
Samuel E. Foote, " 
W. C. Miner, New Haven. 
John A. Porter, " 
Edward E. Salisbury, " 
Benjamin Silliman, Jr., " 
G. B. St. John, « 
J. M. Woolsey, " 
John A. Porter, New London. 
Elbridge Smith, Norwich. 
John W. Stedman, " 
Pierpont Phillips, Pomfret Land'g. 
NEW YORK. 
New York State Library, Albany. 
N. Y. State Cab't of Nat. Hist., " 
Young Men's Association, " 
J. H. Armsby, " 
Charles L. Austin, " 
D. D. Barnard, " 
S. W. Barnard, " 
Rufus G. Beardslee, " 
Anthony Blanchard, Jr., " 
W. E. Bleecker, " 
Uri Burt, " 
William S. Church, " 
Mason F. Cogswell, " 
Erastus Corning, " 
Erastus Corning, Jr., Albany 
Samuel G. Courtney, " 
J. C. Crocker, " 
Alexander Danoson, " 
G. C. Davidson, " 
George Dawson, " 
Edward C. Delavan, " 
Richard Varick DeWitt, " 
William H. DeWitt, " 
L. L. Doty, " 
Archibald A. Dunlop, " 
William Dey Ermand, " 
John E. Gavit, " 
J. P. S. Gifford, XXVII 
LIST OF SUBSCRIBERS. 
James A. Gray, Albany. 
James Hall, " 
David Hamilton, " 
S. H. Hammond, " 
' Ira Harris, " 
Gideon Hawley, " 
Nicholas Hill, Jr., " 
Franklin B. Hough, " 
George B. Hoyt, " 
Friend Humphrey's Sons, " 
Thomas Hun, " 
Washington Hunt, " 
John B. James, " 
Alexander S. Johnson, " 
J. J. Johnson, " 
R. L. Johnson, " 
E. E. Kendrick, " 
James C. Kennedy, " 
Rufus H. King, " 
Charles B. Lansing, " 
E. W. Leavenworth, " 
H. H. Martin, " 
A. McClure, 11 
William McElroy, " 
M. McMahon, " 
F. B. Meek, " 
R. Merrifield, " 
James L. Mitchell, " 
J. Mollinard, " 
J. H. Mulford, " 
J. Munsell, " 
Edward Norton, " 
William J. Noyes, " 
Thomas Olcott, " 
Thomas W. Olcott, " 
A. Osborn, " 
Henry D. Paine, " 
Amasa J. Parker, " 
W. H. Peckham, " 
E. P. Prentice, " 
C. M. Plumb, " 
John V. L. Pruyn, " 
Robert H. Pruyn, " 
H. Pumpelly, " 
John V. P. Quackenbush, " 
A. Ransom, " 
S. H. Ransom, " 
Joel Rathbone, " 
John F. Rathbone, " 
Lewis Rathbone, " 
Narcisse R^mond, Albany. 
Dexter Reynolds, " 
John H. Reynolds, " 
M. T. Reynolds, " 
T. Roessle & Son, " 
V. M. Rice, " 
C. W. Sanford, 
E. Satterlee, " 
M. Schommaker, " 
John L. Schoolcraft, " 
D. B. St. John, " 
V. Ten Eyck, " 
William G. Thomas, " 
Franklin Townsend, " 
Frederick Townsend, " 
Howard Townsend, " 
Robert Townsend, " 
Theodore Townsend, " 
C. Van Benthuysen, " 
S. Oakley Vanderpoel, " 
H. H. Van Dyck, " 
C. Vibbard, " 
Maurice E. Viele, " 
R. H. Waterman, " 
J. I. Werner, " 
W. A. Wharton, " 
Andrew White, " 
John G. White, " 
Eliphalet Wickes, " 
Alfred Wild, " 
A. E. Williams, " 
C. P. Williams, " 
G. L. Wilson, " 
William L. Woollett, Jr., " 
W. A. Young, " 
C. D. Wilbur, Auburn. 
John B. King, Brooklyn. 
John Bard, Barrytown. 
A. J. McCall, Bath. 
William M. Crosby, Binghampton. 
Young Men's Association, Buffalo. 
S. Alexander, " 
W. L. Barnes, " 
John Boardman, " 
S. M. Chamberlain, " 
E. P. Dorr, " 
Wm. Dorsheimer, " 
David Evans, " 
Ellicott Evans, " 
John Ganson, " XXVIII 
LIST OF SUBSCRIBERS. 
R. Hay ford, Buffalo. 
Sanford B. Hunt, " 
George B. Ketchum, " 
Henry L. Lansing, " 
D. S. Manly, " 
H. D. McCullock, " 
W. V. Mercer, Jr., " 
C. Metz, Jr., " 
Everard Palmer, " 
Alex. J. Sheldon, " 
Jas. I. Strang, " 
Charles M. Taintor, " 
A. P. Thompson, " 
D. I. Townsend, " 
M. H. Tyrrell, " 
Wm. S. Van Dugee, " 
Henry K. Veile, " 
Hiram C. White, " 
J. Wilson, " 
Tobias Witmer, " 
Henry B. Gibson, Canandaigua. 
Francis Granger, " 
John Greig, " 
John Rankine, " 
Henry W. Taylor, " 
Thomas Barlow, Canastota. 
Wm. H. Dwindle, Cazenovia. 
J. G. Lowman, West Chemung. 
O. S. Fowler, Fishkill. 
C. Davis, Fishkill Land'ff. 
William H. Denning, " 
William Kent, " 
Henry Winthrop Sargent, " 
Charles M. Walcott, " 
Hermean Soc. of Hobart Coll., Geneva. 
Lyman Wilder, Hoosick Falls. 
John S. Gould, Hudson. 
P. S. Wynkoop, " 
C. C. Cambreleng, Huntington. 
John C. Rhinelander, " 
E. P. Harris, Leroy. 
Genesee College, Lima. 
J. C. Colton, Lockport. 
Phineas L. Ely, " 
William R. Harvey, " 
Charles Morrell, Ludlowville. 
Henry H. Bates, Manlius. 
James Lewis, Mohawk. 
F. E. Spinner, " 
D. W. Bate, Newburg. 
John J. Morrell, Newburg. 
Astor Library, New York. 
Columbia College Library, " 
American Institute, " 
New York Acad, of Medicine, " 
New York Hospital, 11 
N. Y. Society Lib'y, " 
John G. Adams, " 
D. Appleton & Co., 20 copies, " 
William II. Aspinwall, " 
James L. Banks, " 
George Baxter, 11 
N. Bloodgood, " 
J. C. Brevoort, " 
Sidney Brooks, " 
O. A. Brownson, " 
William Bryce, " 
P. M. Bryson, " 
William Coleman Burns, " 
A. O. Butler, " 
E. Vincent Cary, " 
Henry Cary, " 
William F. Cary, " 
E. H. Chapin, " 
Elie Charlier, " 
F. W. Christern, 3 copies, " 
Thomas S. Christy, " 
A. J. Cipriaut, " 
Alonzo Clark, " 
C. C. Clark, 
Daniel J. Coster, " 
Henry A. Coster, " 
F. Cottenet, " 
W. B. Crosby, 
Robert J. Culbert, " 
George William Curtis, " 
James L. Curtis, " 
Charles P. Daly, " 
Thomas B. Dash, " 
Theodore Dehon, " 
William Detmold, " 
James Donaldson, " 
William II. Draper, " 
John D. Dunning, " 
Eugene Dutilh, " 
W. H. Edwards, " 
George T. Elliot, " 
J. M. Emerson, " 
Charles Fairbanks, " 
D. B. Fearing, " XXIX 
LIST OF SUBSCRIBERS. 
Hamilton Fish, New York. 
Mrs. H. L. Fisher, " 
C. S. Francis & Co., 7 copies, " 
John Fry, " 
A. Gesobeidt, " 
Robert P. Getty, " 
Albert Gilbert, " 
C. R. Gilman, " 
J. Grafton, Jr., " 
Albert Granger, " 
C. R. Greene, " 
H. Grinnell, " 
Moses H. Grinnell, " 
Alexander Hamilton, Jr., " 
J. Woodward Haven, " 
Dr. Heusted, " 
Edward S. Hoffman, " 
Wickham Hoffman, " 
Alexander E. Hosack, " 
A. Gerald Hull, " 
A. Gracie King, " 
Edward King, " 
Robert Le Roy, " 
Henry W. T. Mali, " 
Don Mann, " 
Francis Many, " 
J. P, March, " 
L. R. Marshall, " 
Lowell Mason, " 
John T. Metcalf, " 
William G. Mickell, " 
Mrs. William S. Miller, " 
Charles E. Minor, " 
R. B. Minturn, " 
John Moffet, " 
Charles H. Moses, " 
William Curtis Noyes, " 
A. J. Odell, 
Alfred Ogden, " 
George Opdyke, " 
J. W. Otis, " 
Willard Parker, " ' 
Robert Ray, " 
W. C. Redfield, 
James B. Richards, " 
Charles Roome, " 
Henry J. Ruggles, " 
Samuel B. Ruggles, • il 
William C. Schermerhorn, " 
Henry J. Scudder, " 
Alfred Sears, New York. 
Charles E. Strong, " 
Joseph Tuckerman, 3 copies, " 
Lucius Tuckerman, " 
T. Tileston, " 
Elwood Walter, " 
Charles H. Ward, " 
B. Westermann & Co., 2 copies, " 
J. White, " 
John Corlies White, " 
Wiley & Halstead, 4 copies, " 
S. C. Williams, " 
B. R. Winthrop, " 
Theodore Irwin, Oswego. 
S. C. Cleveland, Penn Yan. 
Lewis Brooks, Rochester. 
John W. Dwindle, " 
George H. Ely, " 
L. D. Gowen, " 
Thomas Hamilton, " 
Geo. S. Knight, " 
C. H. Martindale, " 
Selah Matthews, " 
George H. Mumford, " 
John D. Ward, " 
E. H. Shelley, Rome. 
H. A. Kramers, Rotterdam. 
Mrs. Jay Cady, Schenectady. 
J. B. Duane, " 
A. M. Vedder, " 
R. C. Martin, Schoharie. 
John H. Gardner, Sharon Springs. 
T. J. Adams, Syracuse. 
John F. Boynton, " 
R. D. Hamilton, " 
A. R. Shipman, 11 
D. D. Smith, " 
Rensselaer Institute, Troy. 
Young Men's Association, " 
S. A. Cook, " 
Silas L. Covell, " 
Edgar S. Ells, 11 
George Ells, " 
B. Franklin Greene, " 
Benjamin H. Hall, " 
J. Harrison, " 
E. A. Peck, " 
William P. Seymour, " 
Alfred A. Wotkyns, " 
William H. Young, " XXX 
LIST OF SUBSCRIBERS. 
M. M. Bagg, Utica. 
A. S. Copeman, " 
E. Jewett, " 
W. Johnson, " 
Horatio Seymour, " 
John B. Seymour, " 
O. J. Shaw, " 
J. Watson Williams, i " 
Samuel G. Wolcott, Utica. 
Marcellus Wright, Victor. 
T. B. Titus, Vienna. 
H. Davis, Waterville. 
Amos O. Osburn, " 
Library of U. S. Military Acad., West Point. 
C. A. Sparks, Williamsburg. 
M. Weed, Wyoming. 
NEW JERSEY. 
E. Seymour, Bloomfield. 
Samuel Lockwood, Keyport. 
George C. Brown, Mount Holly. 
New Jersey Nat. Hist. Society, Newark. 
Artemas Bigelow, " 
William Kitchell, " 
James Ross, " 
John Whitehead, " 
George H. Cook, ' New Brunswick. 
P. Vanderbilt Spader, New Brunswick. 
Clisophic Soc. of Col. of N. J., Princeton. 
A. Guyot, " 
J. V. Phillips, « 
N. T. Higbie, Rahway. 
J. S. Markle, Trenton. 
J. W. Murphy, " 
Wm. F. Phelps, " 
PENNSYLVANIA. 
Josiah King, Alleghany City. I 
Dickinson College, Carlisle. 
R. M. S. Jackson, Cresson. 
Brackenridge Clemens, Easton. 
J no. H. Bliss, Erie. 
C. W. Tibbals, " 
Ann Haines, Germantown. 
Miss M. H. Morris, " 
Charles S. Pancoast, " 
James B. Richards, " 
George Dock, Harrisburg. 
William H. Egle, " 
John L. Kunkell, " 
Romeo W. Lewis, Honesdale. 
T. L. Budd, Lancaster. 
John Carr, " 
John W. Jackson, " 
F. W. Muhlenberg, " 
John Wise, " 
Alleghany Literary Society, Meadville. 
A. B. Richmond, " 
Hiram L. Richmond, " 
T. F. Thickstone, " 
L. D. Williams, " 
William Corson, Norristown. 
Henry C. Hill, « 
D. H. Mulvaney, " 
Med. Library of Penn. Hospital, Philadelphia. 
Library Company of Phila., " 
Central High School, " 
Walter F. Atlee, " 
Henry Paul Beck, " 
Horace Binney, " 
George H. Boker, " 
I. Rhea Barton, " 
William H. Benade, " 
P. A. Browne, " 
James Bryan, " 
Pierce Butler, " 
H. C. Carey, " 
J. R. Carpenter, " 
Wm. M. Carrington, " 
Stephen Colwell, " 
D. Cowley, " 
O. Wilson Davis, " 
Edward Draper, " 
James Dundas, " 
R. Dunglison, " LIST OF SUBSCRIBERS 
XXXI 
A. L. Elwyn, Philadelphia. 
George W. Fahnestock, " 
John Fallon, " 
C. H. Fisher, " 
Joshua Francis Fisher, " 
J. Foster, " 
Janus Fraiser, " 
John Frazer, " 
Samuel S. Garrigues, " 
F. A. Genth, " 
Henry D. Gilpin, " 
Jno. Grigg, " 
A. Hart, " 
H. Haupt, " 
Howard G. Helmick, " 
Constantine Hering, " 
Hugh L. Hodges, " 
P. I. Horwitz, " 
Joseph R. Ingersoll, " 
Tinsley Jeter, " 
William Keller, " 
Peter Keyser, " 
Thomas Kimber, Jr., " 
Hartman Kuhn, " 
R. LaRoche, " 
Isaac Lea, " 
John LeConte, " 
W. H. Lej^e, " 
R. J. Levis, " 
William I. Linnard, " 
Joseph S. Lovering, " 
Chas. Magarge, " 
H. Pratt McKean, " 
Chas. D. Meigs, " 
S. V. Merrick, " 
John S. Miller, " 
Edward P. Mitchell, " 
S. W. Mitchell, " 
William Fisher Mitchell, Philadelphia. 
Wm. Moore, " 
Israel Morris, " 
Thomas D. Mutter, " 
H. M. Olmstead, " 
Joseph Pancoast, " 
Parry & McMillan, 3 copies, " 
Robert E. Peterson, " 
George Plitt, " 
Edwin L. Reakirt, " 
S. P. Richards, " 
Wm. Sharswood, " 
Smith English & Co., 2 copies, " 
J. Wm. Wallace, " 
E. B. Warren, " 
H. W. Warren, " 
John Weik, " 
Kirk B. Wells, " 
William J. Whitaker, " 
Charles Willing, " 
Thomas B. Wilson, 2 copies, " 
David S. Wiltberger, " 
Geo. B. Wood, " 
Thos. H. Yardley, " 
Mrs. Whitley, Phoenixville. 
Wm. M. Lyon, 2 copies, Pittsburgh. 
Isaac M. Pennock, " 
R. B. Smyser, 11 
Robert B. Sterling, " 
Pottsfield Scientific Society, Pottsville. 
H. A. Lantz, 2 copies, Reading. 
Geo. R. Starkey, " 
Samuel S. Latch, Spread Eagle. 
Geo. Smith, Upper Darby. 
H. D. W. Pawling, Upper Merion. 
Chester Co., Cab. of Nat. His., West Chester. 
Joseph H. Brinton, 11 
Q. Wilson, Wilkins. 
MARYLAND, 
W. R. Handy, Baltimore. 
Chapin A. Harris, " 
John P. Kennedy, " 
George H. Kyle, " 
D. I. McKen, 
George W. Miltenberger, " 
John B. Morris, " 
Maryland Historical Society, Baltimore. 
Mercantile Library Association, " 
L. E. Bailey, " 
Wm. H. Baltzell, " 
Thomas Buckler, " 
James Dwindle, " 
Owen A. Gill, " XXXII 
LIST OF SUBSCRIBERS 
John G. Morris, Baltimore. 
Thos. B. Sargent, u 
William Schley, " 
W. G. Smull, " 
Lewis H. Steiner, " 
W. Chew Van Bibber, " 
A. T. Waugh, Baltimore. 
Thos. B. Steele, Cambridge. 
Samuel Tyler, Frederick City. 
H. H. Harvey, Hagerstown. 
S. H. Jack, Port Deposit. 
DELAWARE. 
J. T. Heald, Wilmington. 
DISTRICT OF COLUMBIA. 
James F. Harrison, Georgetown. 
Charles Lanman, " 
S. Thayer Abert, Washington. 
Smithsonian Inst., 15 copies, " 
U. S. Coast Survey Library, " 
A. D. Bache, " 
Spencer F. Baird, " 
T. T. Everett, " 
L. D. Gale, Washington. 
Le Chevalier Hiilseman, " 
S. H. Huntingdon, " 
Nathan S. Lincoln, " 
J. C. McGuire, " 
T. R. Peale, " 
Count L. F. de Pourtales, " 
C. C. Speiden, " 
VIRGINIA. 
Jno. Vansant, Alexandria. 
J. L. Cabell, Charlotteville. 
F. H. Smith, " 
Randolph Harrison, Cumberland Co. 
Wm. A. Nelson, Fredericksburg. 
Jno. Sedden, " 
J. C. Coleman, Halifax Co. 
Thomas Dun English, Logan Court House., 
John Y. Mason, Jr., Norfolk. 
D. S. Green, Portsmouth. 
A. Morris, Richmond. 
Roanoke College, Roanoke Co. 
Robert Cowan, Staunton. 
John D. Imboden, " 
M. Scheie De Vere, University of Virginia. 
E. H. Moore, Wellsburg. 
NORTII CAROLINA. 
Philanthropic Society, Chapel Hill. 
Dialectic Soc. of Univ'y of N. C., " 
Library of Davidson College, Davidson. 
E. A. Crudup, Granville Co. 
H. W. Guion, Lincolnton. 
E. E. Graham, Newbern. 
R. H. Northrop, Pioneer Mills. 
North Carolina State Library, Raleigh. 
Stephen P. Leeds, Rutherfordton. 
Robert De Schweinitz, Salem. LIST OF SUBSCRIBERS 
XXXIII 
Charles F. Fisher, Salisbury. 
John D. Bellamy, Wilmington. 
Wm. A. Berry, " 
James H. Dickson, " 
D. Du Pre, Jr., " 
H. L. & L. Holmes, " 
William F. Lane, Wilmington. 
James F. McRee, " 
J. L. Meares, " 
S. S. Satchrell, " 
Will. Geo. Thomas, " 
W. C. Willkings, " 
SOUTH CAROLINA. 
Wm. Gregg, Aiken. 
Beaufort Library, Beaufort. 
R. H. Barnwell, " 
Miss Anne Fickling, " 
Henry M. Fuller, " 
John A. Johnson, " 
John Milne, " 
John F. Porteous, " 
Edmund Rhett, " 
Medical Society of S. C., Charleston. 
Charleston Library Society, " 
J. D. Aiken, " 
Samuel G. Barker, " 
Charles M. Cheves, " 
Henry W. De Saussure, " 
Samuel Henry Dickson, " 
Benjamin F. Dunkin, " 
Lingard A. Frampton, " 
James Gaillard, Jr., " 
P. C. Gaillard, 
Robert N. Gourdin, " 
John E. Holbrook, " 
Fr. S. Holmes, " 
Louis Jervey, " 
J. Gadsden King, " 
Mitchell King, " 
G. B. Lartigue, " 
C. T. Lowndes, " 
John McCrady, " 
Henry A. Middleton, " 
E. P. Milliken, 
James Moultrie, " 
I. H. Norman, " 
Thomas L. Ogier, " 
F. S. Parker, " 
John Julius Pringle, " 
Motte A. Pringle, " 
W. B. Pringle, Charleston. 
Julius Porcher, il 
Richard S. Porcher, " 
F. G. Ravenel, " 
Henry Ravenel, " 
H. W. Ravenel, " 
John Ravenel, " 
St. Julien Ravenel, " 
P. Gervais Robinson, " 
A. G. Rose, " 
Thomas P. Smith, " 
Theodore Storrey, " 
Edward N. Thurston, " 
G. A. Trenholm, " 
John B. Waring, " 
John S. White, " 
A. B. Williman, " 
T. E. B. Pegues, Cheraw. 
R. L. Bryan, Columbia. 
Langdon Cheves, " 
Robert W. Gibbes, " 
Maxey Gregg, " 
Allen J. Green, " 
C. F. Hampton, " 
W. Hampton, " 
W. Hampton, Jr., " 
Mrs. D. I. McCord, " 
John S. Preston, " 
Wm. M. Murray, Edisto Island. 
James A. Mims, Erwinton. 
Plowden C. J. Weston, 2 copies, Hagley. 
J. P. Barrett, Newmarket P. O. 
John G. Guignard, Orangeburg Dist. 
L. M. Keitt, " 
P. A. McMichael, " 
G. J. O'Don, " 
W. Harpin Riggs, " XXXIV 
LIST OF SUBSCRIBERS. 
GEORGIA 
Charles P. Crawford, Americus. 
H. K. Daniels, " 
Franklin College, Athens. 
Joseph LeConte, " 
John S. Linton, " 
Young Men's Library Assoc., Augusta. 
Medical College of Georgia, " 
Thos. Barrett, " 
Henry F. Campbell, " 
Robert Campbell, " 
Robt. D. Carmichael, " 
Henry H. Cumming, " 
James W. Daveis, " 
Charles Delaigle, " 
Wm. J. Eve, " 
Wm. H. Goodrich, " 
Wm. H. Harison, " 
Edward Henckle, " 
James Hope, " 
Chas. I. Jenkins, " 
John P. King, " 
L. D. Lallerstadt, " 
John McKinnie, Jr., " 
Henry Moore, " 
Geo. M. Newton, " 
Wm. Phillips, " 
Geo. W. L. Twiggs, " 
Joel Crawford, Bainbridge. 
Joel Crawford, near Blakeley. 
L. B. Mercer, Chenuba. 
J. Van Buren, Clarksville. 
Wm. Gesner, Columbus. 
J. Hamilton Couper, near Darien. 
Wm. C. Daniell, DeKalb Co. 
Mr. Roberts, Dougherty Co. 
Henry Hodges, La Grange. 
J. C. Edwards, Macon. 
M. A. Franklin, « 
John G. Clark, Madison. 
W. L. Jones, " 
George C. Taylor, " 
State Library of Georgia, Milledgeville. 
Lib'y of Oglethorpe University, " 
Phi-delta Soc. Oglethorpe Univ., " 
Thalian Soc. Oglethorpe Univ., " 
Tomlinson Farr, " 
Win. Flinn, Milledgeville, 
C. H. Hall, " 
Mrs. S. K. Talmadge, " 
John S. Thomas, " 
Samuel G. White, " 
Dimas Ponce, Mount Zion. 
Wm. Jones, Riceboro'. 
J. M. Deby, Rome. 
T. D. Adams, Roswell. 
John Dunwody, " 
Jas. R. King, " 
Thos. E. King, " 
Wm. Nephew King, " 
N. A. Pratt, Jr., " 
Savannah Medical College, Savannah. 
Robert A. Allen, " 
G. W. Anderson, " 
Richard D. Arnold, " 
William S. Basinger, " 
H. C. Berrie, " 
H. L. Byrd, " 
Solomon Cohen, " 
John M. Cooper, " 
C. A. L. Damar, " 
Dr. Davis, " 
John D. Fish, " 
William Neyle Habersham, " 
N. A. Hardee, " 
W. B. Hodgson, " 
J. G. Howard, " 
R. Hutcheson, " 
Augustus Seaborn Jones, " 
S. Yates Levy, " 
Andrew Low, " 
William Mackay, " 
John W. Nevitt, " 
William C. O'Driscoll, " 
F. H. Orme, " 
Edward Padelford, " 
James B. Read, " 
Philip T. Schley, " 
James T. Screven, " 
Alexander A. Smets, " 
P. L. Wade, " 
George H. Waring, " 
James M. Wayne, " LIST OF SUBSCRIBERS. 
XXXV 
Charles W. West, Savannah. 
Wm. H. Wiltbergen, " 
Wilson C. Cooper, Scriven Co. 
Mrs. Lucie Terrell Dawson, Sparta. 
Wm. H. Hall, Thomasville. 
C. S. Rockwell, " 
C. Rauschenberg, Varnell's Station. 
J. P. Stevens, Walthourville. 
ALABAMA. 
John Darby, Auburn. 
Origen Sibley, Baldwin Co. 
Isaac Croom, Greensboro'. 
Fabius F. Hill, " 
Robert B. Waller, " 
H. Tutwiler, Havana. 
A. Donald, Manningham. 
N. R. Davis, Marion. 
Jesse P. Carter, Mobile. 
W. C. Easton, " 
E. P. Gaines, " 
Henry L. Gaines, " 
Garland Goode, " 
B. F. Higgins, Mobile. 
Dudley Hubbard, " 
John F. Innerarity, " 
T. S. James, " 
A. Loper, " 
William McMillan, " 
Dr. Mastin, " 
E. R. Mordecai, " 
J. C. Nott, " 
Sami. Ruffin, " 
Albert Stein, • " 
Thomas M. Peters, Moulton. 
Richard Clark, Union Town. 
FLORIDA. 
Mrs. C. Forsyth, Milton. 
Wm. J. Keyser, " 
E. E. Simpson, Milton. 
MISSISSIPPI. 
S. S. Boyd, Natchez. 
Benj. Chase, " 
S. M. Davis, " 
H. S. Eustis, " 
Sami. H. Lambdin, " 
James Metcalfe, " 
Benj. Roach, " 
Winthrop Sargent, " 
Wm. D. Moore, Oakland Coll. 
Library of Univ, of Mississippi, Oxford. 
L. Harper, " 
Eugene W. Hilgard, " 
J. Boyd Elliott, near Port Gibson. 
G. W. Humphreys, Port Gibson. 
M. Emanuel, Vicksburg. 
Jefferson College, Washington. XXXVI 
LIST OF SUBSCRIBERS. 
LOUISIANA. 
George D. Anderson, Alexandria. 
Louisiana State Library, Baton Rouge. 
F. I. B. Romer, " 
R. C. White, " 
Julian Tournillion, Bayou Lafourche. 
Thomas Cottman, Donaldsonville. 
Henry Gibbon, Franklin. 
John Middleton Huger, " 
C. M. Smith, " 
N. O. Academy of Sciences, New Orleans. 
New Orleans Club, " 
Thomas AlHeck, " 
A. C. Ainger, " 
N. B. Benedict, " 
W. C. Black, " 
P. E. Bonford, " 
D. Warren Brickell, " 
Charles Briggs, " 
Richard E. Butler, " 
Thomas Byrne, " 
R. H. Chilton, " 
Wm. P. Converse, Jr., " 
J. S. Copes, " 
T. C. Copes, " 
J. L. Crawcour, " 
G. W. Dirmeyer, " 
Wm. C. Driver, " 
Greer B. Duncan, " 
I. A. Florat, " 
Lafayette Folger, " 
D. M. Hildreth, " 
G. W. Hynson, New Orleans. 
H. P. Janvier, " 
N. R. Jennings, " 
R. C. Kerr, " 
W. T. Leacock, " 
W. B. Lindsay, " 
Joseph H. Maddox, " 
Joseph Mather, " 
P. B. McKelvey, " 
D. F. Mitchell, " 
S. L. Moss, " 
Gustavus A. Nott, " 
J. H. Oglesby, " 
Edward Parmele, " 
John Pemberton, " 
William Prehn, " 
Alex. F. Pugh, " 
James Robb, " 
J. G. Robinson, " 
Rudolph Schwartze, " 
J. C. Shannon, " 
R. D. Shepherd, " 
Howard Smith, " 
J. Tuyes, " 
H. McNeil Vance, " 
John Watt, " 
E. C. Wharton, " 
G. A. Briant, Pattersonville. 
D. L. McLaughlin, St. Francisville. 
A. Millspaugh, Washington. 
ARKANSAS. 
Wm. E. Ashley, Little Rock. 
S. H. Hempstead, " 
Albert Pike, Little Rock. 
John E. Reardon, " 
TENNESSEE. 
W. M. Stuart, Clarksville. 
E. K. Smith, Fort Mason. 
G. Purnell Phillips, Greenbottom, P. O. 
Cumberland University, Lebanon. LIST OF SUBSCRIBERS 
XXXVII 
N. Lawrence Lindsley, Lebanon. 
J. M. Safford, " 
J. C. Bowden, McMinnville. 
J. J. Hooks, Memphis. 
U. B. Morrow, " 
A. K. Taylor, 44 
State Library of Tennessee, Nashville. 
Med. Depart, of U. of Nashville, 44 
Wm. T. Briggs, 44 
Mrs. Lizinka Brown, 44 
Wm. L. Brown, 44 
Philip L. Crackett, 44 
R. E. Deery, 44 
W. M. B. Evans, 44 
H. M. R. Fogg, Nashville. 
R. C. Foster, 44 
Robt. C. Foster, 4th, 44 
I. W. Hoyte, 44 
John Kimberly, 44 
A. V. S. Lindsley, 44 
J. Berrien Lindsley, 44 
A. B. Montgomery, 44 
S. D. Morgan, 44 
Richard Owen, 44 
Alex. J. Porter, 44 
Arthur M. Rutledge, 44 
T. C. McNeill, Paris. 
KENTUCKY. 
C. W. Short, Hayfield. 
Willis I. Hudson, Lexington. 
Wm. Byrd Powell, Covington. 
A. B. Stark, Elkton. 
OHIO. 
J. Tingley, Berea. 
Wm. Martin, Castalia. 
Western Acad, of Nat. Sciences, Cincinnati. 
Young Men's Merc. Lib. Assoc., 44 
Larz Anderson, 44 
John G. Anthony, 44 
Flamen Ball, 44 
Geo. W. D. Bickley, 44 
David Bolles, 44 
R. Buchanan, 44 
R. W. Burnet, 44 
S. T. Carley, 44 
Joseph Clark, 44 
Robert Clarke, 44 
William H. Cook, 44 
Thomas Corwin, 44 
Z. Freeman, 44 
Erasmus Gest, 44 
William Greene, 44 
H. C. Grosvenor, 44 
Samuel M. Hart, 44 
John R. Haynes, 44 
George Hoadly, Jr., Cincinnati. 
William Hooper, 44 
William M. Hubbell, 44 
T. D. Lincoln, 44 
Joseph Longworth, 44 
George M. Maclean, 44 
George Mendenhall, 44 
Edward Mills, 44 
John L. Miner, 44 
C. Moore, 44 
William H. Mussey, 44 
R. S. Newton, 44 
Charles Coolidge Pomeroy, 44 
George E. Pugh, 44 
A. G. Ray, 
Joseph Reakirt, 44 
Jacob Resor, 44 
William Resor, 44 
William T. Roelafson, 44 
William S. Sampson, 44 
Charles F. Schmidt, 44 
Alphonso Taft, 44 XXXVIII 
LIST OF SUBSCRIBERS 
John L. Talbott, Cincinnati. 
R. M. W. Taylor, " 
Truman & Spofford, 5 copies, " 
E. S. Wayne, " 
John Lynch, Circleville. 
N. J. Turney, " 
Thomas Brown, Cleveland. 
John Kirkpatrick, " 
S. H. Klippart, " 
Joseph Perkins, " 
Ohio State Library, Columbus. 
Ohio Inst, for Deaf and Dumb, " 
Blind Asylum, " 
L. Heyl, ' " 
A. Huston, " 
William A. Neil, " 
William A. Platt, " 
J. H. Riley & Co., " 
James H. Smith, " 
Joseph Sullivant, " 
W. S. Sullivant, " 
E. N. Sill, Cuyahoga Falls. 
Robert W. Steele, Dayton. 
John W. Van Cleve, " 
Pliny M. Crume, Eaton. 
A. A. Bliss, Elyria. 
Rollin C. Dewitt, " 
Albert Ely, " 
C. A. Ely, 
Hernan Ely, " 
John W. Hulbert, " 
Edwin Kelley, " 
E. E. Mussey, " 
H. M. Redington, " 
N. S. Townshend, " 
David Christy, Glendale. 
I. I. Penfield, Huron. 
W. H. & J. N. Myers, Loudonville. 
Marietta College, Marietta. 
E. B. Andrews, " 
Josiah D. Cotton, " 
Wm. S. Ward, " 
Whittlesey Academy, Norwalk. 
C. B. Stickney, " 
Samuel T. Worcester, " 
Geo. N. Allen, Oberlin. 
Theophilus W. Guy, Oxford. 
V. B. Horton, Pomeroy. 
E. D. Collier, Steubenville. 
James Pillars, Tiffin. 
Young Men's Association, Toledo. 
Thomas Dunlap, " 
A. J. Field, " 
John Fitch, " 
S. Fitch, Jr., " 
Is. N. Hazlett, " 
Charles W. Hill, " 
Hez. L. Hosmer, " 
W. J. B. Hubbell, " 
Josiah Hurtzel, " 
M. Johnson, " 
W. W. Jones, " 
Charles Kent, " 
Jon. Joy Laman, " 
Daniel McBain, " 
Charles Pratt, " 
Wm. H. Ray morn, " 
Samuel R. Reed, " 
Richard Waite, " 
R. W. Furnas, Troy. 
J. T. Mathias, Tyrone Forges. 
A. L. Rankin, Yellow Springs. 
MICHIGAN. 
Franklin Hubbard, Adrian. 
University of Michigan, Ann-Arbor. 
E. B. Pond, " 
A. Sager, " 
Henry P. Tappan, " 
A. Winchell, . " 
I. Carpenter, Blissfield. 
W. N. Carpenter, Detroit. 
Z. Chandler, Detroit. * 
M. Wenton Field, " 
L. L. Jones, " 
E. A. Wales, " 
E. B. Ward, 
Samuel W. Hill, Eagle Harbor. 
M. D. Senter, Eagle River. 
Charles Whittlesey, " LIST OF SUBSCRIBERS. 
XXXIX 
W. W. Booth, Fentonville. 
Flint Scientific Institute, Flint. 
G. M. Dewey, " 
George M. Dewey, Lansing. 
A. H. Jones, Marquette. 
A. S. Heaton, N. West Mine. 
J. E. Hyde, N. West Mine. 
E. N. Bartlett, Olivet. 
D. C. Jacokes, Pontiac. 
Geo. Lathrop, Saginaw. 
Samuel Whitney, Saut St. Marie. 
INDIANA. 
James Speer, Brookville. 
J. C. Applegate, Delphi. 
George Bowman, " 
B. F. Schermerhorn, " 
E. P. Cole, Evansville. 
J. L. Reynolds, Lafayette. 
Horace P. Biddle, Logansport. 
Thomas B. Helm, " 
O. P. Baer, Richmond. 
ILLINOIS. 
W. D. Haley, Alton. 
Fayette B. Hamblin, Belvidere. 
Charles W. Richardson, " 
George H. Holliday, Carlinville. 
E. Andrews, Chicago. 
Joseph B. Austin, " 
James V. Z. Blaney, " 
J. H. Burch, " 
Charles W. Colson, " 
J. L. Elwood, " 
John Evans, " 
F. L. Fake, " 
C. A. Fowler, " 
William B. Herrick, " 
H. A. Johnson, " 
M. D. Ogden, " 
J. Y. Scammon, " 
Mark Skinner, " 
J. D. Webster, " 
O. C. Dake, Edwardsville. 
E. Hamilton Truex, Galena. 
Albert Hurd, Galesburg. 
M. K. Taylor, " 
Philena Fobes, Godfrey. 
J. L. Jenkins, Granville. 
Graham Lee, Hamlet. 
Nelson D. Elwood, Joliet. 
William B. Christopher, Lacon. 
James Chapman, Moline. 
H. C. Ford, " 
J. M. Gould, " 
Kirtley Ryland, " 
H. F. Sickels, " 
R. N. Tate, " 
Samuel Sargent, Mt. Pulaski. 
William H. Young, " 
Wm. Chumasero, Ottawa. 
Bronson Murry, " 
Frederick Brendel!, Peoria. 
Addison R. Bodley, Princeton. 
George P. Giddings, Quincy. 
S. G. Chellis, Rockford. 
Rock Island Libr'y Association, Rock Island. 
Albert G. Brackett, " 
Brackett & Bulkley, " 
F. C. Duncan, " 
C. M. Osborne, " 
Robert J. Wilcox, Sheffield. 
F. B. Haller, Vandalia. 
Ezra Jenkins, " 
A. D. Stearns, " 
A. B. West, 11 XL 
LIST OF SUBSCRIBERS. 
MISSOURI. 
G. C. Swallow, Columbia. 
Academy of Science, St. Louis. 
Mercantile Library, " 
Thomas Allen, " 
F. E. Baumgarten, " 
Jeff. K. Clark, " 
James P. Cuddy, " 
Lewis Dorsheimer, " 
George Engelmann, " 
Edward J. Glasgow, " 
J. Z. Hall, " 
R. S. Holmes, " 
Wm. Homes, " 
John How, " 
Wm. Johnston, " 
J. French Judge, " 
M. V. Kercheval, " 
Loker, Reneck & Co., " 
J. Lucas, St. Louis. 
W. S. Maddock, " 
John Moss, " 
Robt. W. Oliphant, " 
Charles A. Pope, " 
Joseph Ridgeway, " 
John I. Roe, " 
B. F. Shumard, " 
James Smith, Jr., " 
Spencer Smith, " 
C. W. Spalding, " 
Isaac H. Sturgeon, " 
Charles F. Vanderford, " 
J. H. Watters, " 
Henry W. Williams, " 
A. Wislizenus, " 
James E. Yeatman, " 
IOWA. 
Moses Cousins, Jr., Albia. 
Iowa Hist, and Geolog. Inst., Burlington. 
Milton D. Comstock, " 
John M. Corse, " 
T. D. Crocker, 
D. S. Ebersoll, " 
A. T. Garthe, " 
J. Gilbert, " 
W. D. Gilbert, " 
A. D. Green, " 
James W. Grimes, " 
J. C. Hall, 
Edwin James, " 
Chas. Mason, " 
James Putn, " 
E. D. Rand, " 
John H. Rauch, " 
David Rorer, " 
H. Scholer, " 
Henry W. Starr, " 
Wm. Thompson, " 
Fitz Henry Warren, " 
T. B. Wigfall, Burlington. 
Young Men's Literary Assoc., Davenport, 
J. M. Adler, " 
A. H. Barrow, " 
W. Barrows, " 
N. L. Beuten, " 
B. B. Brayton, " 
Wardell Bunting, " 
J. M. D. Burrows, " 
G. W. Carter, " 
R. Christie, " 
Eben. Cook, " 
John S. Davies, " 
John F. Dillon, « 
Nicholas Fejervari, " 
Wm. H. Fleming, " 
C. Goodrich, " 
James T. Hogane, " 
Jos. Lambrite, « 
S. R. Millar, 
C. C. Parry, " 
H. Price, " LIST OF SUBSCRIBERS. 
XLI 
Wm. H. Rowe, Davenport. 
A. Sanders, u 
Ignatius Sanger, " 
Geo. B. Sargent, " 
D. S. Sheldon, " 
M. Thompson, Davenport. 
Dolphus Torrey, " 
Alexander College, Dubuque. 
J. A. Nash, Fort Des Moines. 
W. H. Tuthill, Tipton. 
WISCONSIN. 
Lawrence University, Appleton. 
Theodore Conkey, " 
R. Z. Mason, " 
James M. Phinney, " 
Perry H. Smith, " 
E. F. Fockler, Center. 
John Hustis, Hustisford. 
E. W. Evans, Kenosha. 
Geo. Delaplaine, Madison. 
Alex. Schue, " 
Young Men's Association, Milwaukee. 
J. K. Bartlett, " 
James S. Buck, " 
Jeremiah Curtin, " 
Increase A. Lapham, Milwaukee. 
John Lockwood, " 
Lieut. Gov. McArthur, " 
J. F. McMullen, " 
Thomas L. Ogden, " 
James H. Rogers, " 
George D. Wilber, Mineral Point 
Lewis Rob, Monroe. 
J. W. Richardson, Portage City. 
Solomon T. Richardson, Poynett. 
Racine College, Racine. 
P. R. Hoy, " 
John G. McMynn, " 
TEXAS. 
J. T. Allen, Austin. 
Charles W. Pressler, " 
Mr. Wilke, " 
W. H. Stevens, Galveston. 
Tipton Walker, Galveston. 
George Holley, Georgetown. 
Th. Koester, New Braunfels. 
Dr. Herff, San Antonio. 
CALIFORNIA. 
San Francisco, 
u 
G 
g 
u 
g 
g 
g 
g 
J. Flatt, Benicia. 
William Meyer, Elton. 
Thomas M. Logan, Sacramento. 
A. C. Monson, " 
Society of California Pioneers, San Francisco. 
William F. Babcock, " 
Theodore A. Barry, " 
Frederick Billings, " 
G. W. P. Bissell, " 
A. J. Bowie, 
A. F. Branda, 
T. G. Cary, Jr., 
Charles L. Case, 
R. Beverly Cole, 
Charles H. Cushing, 
J. N. Eckle, 2 copies, 
John B. Felton, 
J. Friedlander, XLII 
LIST OF SUBSCRIBERS 
Daniel Gibb, San Francisco. 
C. S. Hathaway, " 
Joshua P. Haven, " 
George H. Howard, " 
Edward Jones, " 
Alexander Kirchner, " 
Delos Lake, " 
A. Felix Leinan, " 
F. W. Macondray, " 
J. May, " 
Louis McLane, Jr., " 
Jonas Minturn, " 
Theodore F. Moss, " 
John A. Munroe, " 
Joseph C. Palmer, " 
Levi Parsons, San Francisco. 
Charles B. Polhemus, " 
Leander Ransom, " 
Julius K. Rose, " 
A. F. Sawyer, " 
Air. Sloat, " 
Arthur B. Stout, " 
Eugene A. Upton, " 
C. F. Winslow, " 
John Donald, San Mateo. 
E. S. Holden, Stockton. 
C. W. Norcom, " 
Robert R. Reid, " 
W. M. Ryer, " 
MINESOTA. 
Solon W. Manny, Fort Ripley. 
J. C. Moulton, St. Anthony. 
Daniel A. Robertson, St. Paul. 
J. S. Sewall, " 
KANSAS. 
E. M. Perrin, Council City. 
| W. I. R. Blackman, Lawrence. 
SUBSCRIBERS IN THE BRITISH PROVINCES 
CANADA. 
McGill College, Montreal. 
Mechanics' Institute, " 
Natural History Society, " 
B. Dawson, " 
Jacob De Witt, " 
C. Dorwin, " 
Geo. II. Frothingham, " 
John Frothingham, " 
J. W. Haldimand, " 
Hill & Martin, " 
L. H. Holton, " 
Benjamin Lyman, " 
David Allan Poe, Montreal. 
J. G. Shipway, " 
Romeo II. Stephens, " 
Dr. Wheeler, " 
John Young, " 
John M. Young, " 
E. Billings, Ottawa. 
Mechanics' Institute, Perth. 
John MacLean Bell, " 
Daniel Mac Martin, " 
W. J. Morris, " 
Jas. Wilson, " LIST OF SUBSCRIBERS 
XLIII 
Oliver Wells, Three Rivers. 
Library of Legislative Council, Toronto. 
Legislative Assembly Library, " 
Trinity College, " 
Geo. W. Allen, " 
A. H. Armour & Co., 4 copies, " 
H. Croft, " 
P. Freeland, " 
John Harrington, " 
Prof. Hincks, " 
Dr. Hodder, " 
John Leys, " 
W. I. Macdonell, Toronto. 
Angus Morrison, " 
George Patton, " 
John Patton, " 
John B. Robinson, " 
Henry Rowsell, " 
F. H. Simpson, " 
E. F. Whittemore, " 
Benjamin Workman, " 
H. H. Wright, 
Thomas Cottle, Woodstock. 
NEW BRUNSWICK. 
King's College Library, Fredericton, 
N. B. Legislative Library, " 
M. H. Perley, St John. 
NOVA SCOTIA. 
King's College, Halifax. 
P. Carteret Hill, " 
J. M. Cramp, Horton. 
John Chase, Wolfville. 
A. P. S. Stuart, " 
SUBSCRIBERS IN EUROPE 
AUSTRIA. 
The Imperial Library, Vienna. 
। The Imperial Geol. Society, Vienna. 
ENGLAND 
University Library, Cambridge. 
H. Bail!iere, London. 
Junius S. Morgan, " 
Amelia M. Murray, " 
Philip Lutley Sclater, " 
J. Hubbard Sturgis, London. 
Nicholas Triibner, " 
Triibner & Co., 50 copies, " 
Queen's College Library, Oxford. 
J. H. Parker & Son, " XLIV 
LIST OF SUBSCRIBERS. 
HOLLAND AND ITALY. 
J. van der Hoeven, Leiden. 
| Institute di Scienze, Lettere ed Arti, Venice. 
PRUSSIA. 
His Majesty, the King, Frederick William IV., Berlin. 
SAXONY. 
F. R. Broekhaus, Leipzig. 
SWITZERLAND. 
Peter Merian, Basel. 
| Auguste Mayor, Neuchatel. 
SUBSCRIBERS IN SOUTH AMERICA AND THE PHILIPPINES. 
H. C. Focke, Surinam. 
C. T. Hering, " 
Charles Griswold, Manila. T A 11 L E 0 E CONTENTS. 
PART I. 
ESSAY ON CLASSIFICATION. 
CHAPTER I. 
THE FUNDAMENTAL RELATIONS OF ANIMALS TO ONE ANOTHER AND TO THE WORLD IN WHICH 
THEY LIVE, AS THE BASIS OF THE NATURAL SYSTEM OF ANIMALS. 
Section 1. The leading features of a natural zoological 
system are all founded in nature. - There is but one 
system, and that is to be read in nature, and was not 
devised by man. The essential divisions of that system 
cannot be arbitrary, p. 3-12. 
Section 2. Simultaneous existence of the most diversified 
types under identical circumstances. - Organized beings 
of the most different structure are everywhere found 
together, p. 12-16. 
Section 3. Repetition of identical types under the most 
diversified circumstances. - Organized beings with the 
same structure occur in the most different parts of the 
world, p. 16, 17. 
Section 4. Unity of plan in otherwise highly diversified 
types. - The greatest diversity of form and of compli- 
cation of structure may be found under the same plan 
of structure, p. 18, 19. 
Section 5. Correspondence in the details of structure in 
animals otherwise entirely disconnected. - Animals, be- 
tween which no genetic relation can be traced, may 
nevertheless exhibit the most astonishing correspond- 
ence in the details of their structure, p. 19-21. 
Section 6. Various degrees and different kinds of relation- 
ship among animals. - Animals differ from one another, 
not only in degree; there are also different kinds of 
differences, p. 21-23. 
Section 7. Simultaneous existence in the earliest geological 
periods of all the great types of animals. - The leading 
types of the animal kingdom have made their appear- 
ance upon the surface of our globe at the same 
time, p. 23-25. 
Section 8. The gradation of structure among animals.- 
There is a gradation among animals, though they do 
not form one continuous series, p. 26-30. 
Section 9. Range of geographical distribution of animals. 
- The range of distribution of different kinds of ani 
mals is very unequal. Faunae, p. 30-36. 
Section 10. Identity of structure of widely different types. 
- Animals found within entirely disconnected areas 
may have the same structure, p. 36-40. 
Section 11. Community of structure among animals living 
in the same regions. - Animals occupying the same re- 
gion exhibit sometimes a remarkable similarity of 
structure, p. 41-43. XLVI 
TABLE OF CONTENTS. 
Section 12. Serial connection in the structure of animals 
widely scattered upon the surface of our globe. - Animals 
living in different parts of the world form frequently 
series which are closely linked together, p. 43-47. 
Section 13. Relation between the size of animals and their 
structure. - Though apparently of secondary impor- 
tance, the size of animals bears a definite relation to 
their structure, p. 4 7-49. 
Section 14. Relation between the size of animals and the 
mediums in which they live. - There is also a definite 
relation between the size of animals and th.e mediums 
in which they live, p. 49-50. 
Section 15. Permanency of specif c peculiarities in all or- 
ganized beings.- Immutability of species, p. 51-56. 
Section 16. Relations between animals and plants and the 
surrounding world. - There exist definite relations be- 
tween the animals and plants, and the conditions under 
which they live. Habits of animals, p. 57-63. 
Section 17. Relations of individuals to one another.- 
The relations in which individual animals stand to one 
another are well defined in nature, p. 63-66. 
Section 18. Metamorphoses of animals. - Importance of 
Embryology. Works upon this subject. Polypi, Aca- 
lephs, Echinoderms, Classes of Radiata. Mollusks, 
their affinities and development. Articulata, their 
range and affinities. Worms, Crustacea, Insects. Ver- 
tebrata. Embryology furnishes standards to determine 
the relative rank among animals. Distinction between 
homologies and analogies. Independence of the devel- 
opment of animals from external causes, p. 66-88. 
Section 19. Duration of life. - There is the greatest 
diversity in the average duration of the life of different 
kinds of animals, p. 88-89. 
Section 20. Alternate generations.- There are animals 
the successive generations of which are not identical, 
though their differences are circumscribed within defi- 
nite cycles, p. 90-93. 
Section 21. Succession of animals and plants in geolog- 
ical times. - The succession of organized beings in past 
geological ages exhibits biological phenomena of the 
most complicated nature, requiring an extensive ac- 
quaintance with Zoology, Comparative Anatomy, and 
Embryology, to be rightly appreciated. Works re- 
lating to the fossil remains of different classes and of 
different geological periods. Difference between the 
organic and inorganic kingdoms, p. 93-101. 
Section 22. Location of types in past ages. - The geo- 
graphical distribution of some types of animals was cir- 
cumscribed within similar limits in past ages and 
now, p. 102-103. 
Section 23. Limitation of species to particular geological 
periods. - Not only species, but all other groups of ani- 
mals and plants, have a definite range of duration, 
p. 104-106. 
Section 24. Parallelism between the geological succession 
of animals and plants and their present relative standing. 
- The relative rank of the animals now living coin- 
cides with the order of succession of their representa- 
tives in past ages, p. 107-112. 
Section 25. Parallelism between the geological succession 
of animals and the embryonic growth of their living rep- 
resentatives. - The changes which animals undergo 
during their embryonic growth coincide also with the 
order of succession of the fossils of the same types in 
past ages, p. 112-116. 
Section 26. Prophetic types among animals. - Distinction 
between prophetic, progressive, and synthetic types. 
A deeper insight into these relations is indispensable, 
in order to appreciate the succession of organized 
beings in past times, p. 116-118. 
Section 27. Parallelism between the structural gradation 
of animals and their embryonic growth. - The phases 
of development of animals coincide with the different 
levels in the gradation of their respective types, p. 
118-120. 
Section 28. Relations between the structure, embryonic 
growth, geological succession, and the geographical distri- 
bution of animals. - The geographical distribution of 
animals upon the surface of the globe bears direct rela- 
tions to the rank, the embryonic growth, and the geo- 
logical succession of their respective types, p. 120-122. 
Section 29. Mutual dependence of the animal and vegeta- 
ble kingdoms. - The animal and vegetable kingdoms 
are dependent upon one another, and stand in harmo- 
nious relation, p. 122-123. 
Section 30. Parasitic animals and plants. - Various de- 
grees and different kinds of parasitism among animals 
and plants. Parasites do not form natural groups, 
p. 123-127. 
Section 31. Combination in time and space of various 
kinds of relations among animals. - There is not only a 
striking relation between the rank of animals, their 
embryonic growth, their geological succession, and their 
geographical distribution, but even between organized 
beings and some of the members of our solar system, 
p. 127-131. 
Section 32. Recapitulation. - Bearing of the points con- 
sidered in the preceding Sections upon the question of 
the origin of organized beings. What Classification 
should be. p. 132-136. TABLE OF CONTENTS. 
XLVII 
CHAPTER II. 
LEADING GROUPS OF THE EXISTING SYSTEMS OF ANIMALS. 
Section 1. Great types or branches of the animal kingdom. 
- Attempt to define the fundamental divisions of the 
animal kingdom. Early classifications. Comparison 
of the writings of different authors with the view of 
determining what are natural groups among animals. 
The great branches of the animal kingdom are charac- 
terized by the plan of their structure, p. 137-144. 
Section 2. Classes of animals. - Classes are natural 
divisions, characterized by the manner in which the 
plan of their respective great types is executed, and by 
the means employed in the execution. Structure con- 
sidered in different points of view. p. 145-150. 
Section 3. Orders among animals. - Orders are natural 
groups founded upon the degree of complication of the 
structure. Relative rank or standing among animals, 
p.150-155. 
Section 4. Families. - Families are natural groups 
founded upon the form of animals. Indefinite use thus 
far made of the form in characterizing animals. Im- 
portance of greater precision in that respect, p. 
155-161. 
Section 5. Genera. - Linmeus' view of genera. Latreille. 
Genera are natural groups based upon the ultimate de- 
tails of structure, p. 161-163. 
Section 6. Species. - Generally but wrongly based upon 
fecundity. Hybridity, individuality, alternate genera- 
tions, polymorphism. Species exist in nature in the 
same manner as any other natural groups; they are 
based upon well determined relations of individuals to 
one another and to the world around them, and upon 
the proportions, the ornamentation, and the relations 
of their parts, p. 163-170. 
Section 7. Other natural divisions among animals. - Be- 
sides branches, classes, orders, families, genera, and 
species, which express the fundamental categories of 
the existence of animals, there occur here and there 
further natural subdivisions, p. 170-172. 
Section 8. Successive development of characters. - In the 
development of animals, the characteristic features do 
not appear in the order of their systematic dignity. 
Their succession still requires careful study, p. 
172-176. 
Section 9. Conclusions. - Classification is a philosophical 
study of the greatest importance, p. 177-178. 
CHAPTER III. 
NOTICE OF THE PRINCIPAL SYSTEMS OF ZOOLOGY. 
Section 1. General remarks upon modern systems. - 
Their aim and discrepancies. Desirable improvements. 
Limits of the fundamental divisions with their respec- 
tive classes. Rhizopoda and Infusoria. Radiata, with 
three classes; Mollusks, with three classes; Articulata, 
with three classes; Vertebrata, with eight classes, 
p. 179-187. 
Section 2. Early attempts to classify animals. - Leading 
groups recognized by Aristotle, p. 187-189. 
Section 3. Period of Linnceus.- Linnaeus was the first 
to present a definite system as expressing the natural 
affinities among animals, p. 189-192. 
Section 4. Period of Cuvier, and anatomical systems.- 
Four types among animals first recognized by Cuvier, 
p. 193. Classification of Cuvier, p. 194. Irregularities 
of this system, p. 195. Classification of Lamarck, p. 
196. Its principle, p. 197. Classification of DeBlain- 
ville, p. 198. Compared with those of Lamarck and 
Cuvier, p. 199. Classification of Ehrenberg, p. 200. 
Its principle, p. 201. Classification of Burmeister, p. 
203. Classification of Owen, p. 204. Compared with 
those of Cuvier and von Siebold, p. 205. Growing re- 
semblance of modern systems, p. 206. Classification of 
Milne Edwards, p. 207. Classification of von Siebold XLVIII 
TABLE OF CONTENTS. 
and Stannius, p. 208. Classification of Leuckart, p. 
209. General remarks upon anatomical classifications, 
p. 210. 
Section 5. Physiophilosophical systems. - Oken's views 
and influence upon the progress of Zoology, p. 211. 
Uis classification, p. 212. Classification of Fitzinger, 
p. 214. Classification of McLeay, p. 216. Affinity and 
analogy, p. 216-220. 
Section 6. Embryological systems. - Influence of Dollin- 
ger, p. 220. K. E. von Baer as a systematic writer, p. 
220-226. Uis classification, p. 226. Classification of 
Van Beneden, p. 227. Diagram of the development of 
animals by Kblliker, p. 229. Classification of Vogt, p. 
230. Further advance in perfecting the system of 
zoology is chiefly to be expected from embryological 
investigations. 
PART II. 
NORTH AMERICAN TESTUDINATA. 
CHAPTER I. 
THE ORDER OF TESTUDINATA: ITS RANK, CLASSIFICATION, 
r, AND GENERAL CHARACTERS. 
Section 1. Rank of the Testudinata. - The Testudinata 
constitute an order in the class of Reptiles. The plan 
of structure of the Vertebrata. Natural limits of the 
class of Reptiles, p. 235-240. 
Section 2. Special classification of Testudinata. - The 
Testudinata constitute two sub-orders, which embrace 
several natural families, p. 241-252. 
Section 3. Essential characters of the order of Testudi- 
nata.- Their essential character lies not so much in 
their shield, as in the special development of the 
different regions of the body, which assigns to them 
the highest rank in their class, p. 252-255. 
Section 4. The Shield. - The shield consists of parts of 
the true skeleton, and of ossifications of the skin, or 
rather of the walls of the body, which overlie the true 
skeleton, p. 255-257. 
Section 5. The Skin.- The epidermis, p. 257. The 
colors in Turtles, p. 261. The corium, p. 263. 
Section 6. The Skeleton. - Head, p. 265. Vertebra?, p. 
266. Ribs, p. 267. Sternum, p. 267. Limbs, p. 267. 
Section 7. The Muscles, p. 270. 
Section 8. The Nervous System, p. 274. 
Section 9. The Organs of the Senses. - The ear, p. 275. 
The eye, p. 276. The nose, p. 276. The tongue and 
mouth, p. 277. 
Section 10. Eating, Drinking, and Digestive Apparatus, 
p. 278. 
Section 11. The Respiration, p. 281. Table showing the 
capacity of the lungs compared with the weight of the 
body, p. 283. 
Section 12. The Vascular System, p. 285. 
Section 13. The Urogenital Organs.- Urinary organs, 
p. 287. Genital organs, p. 287. 
Section 14. The developmen t of Turtles from a zoological 
point of view, p. 290. Table showing the successive 
changes in the relative dimensions of the body in Emy- 
doidse, p. 292. 
Section 15. The psychological development of Turtles com- 
pared with that of the other orders of Reptiles. Too little 
attention is now paid to the faculties of animals, p. 296. 
Section 16. Geographical distribution of the Testudinata. 
Great discrepancy between the range of marine Tur- 
tles compared with that of the land and fresh water 
types, p. 301. 
Section 17. First appearance of Testudinata upon our 
globe, p. 303. Table showing the period of the first 
appearance of the Testudinata compared with that of 
the other animals, p. 306. 
Section 18. Sub-orders of Testudinata. - The sub-orders 
of sea Turtles, Chelonii, p. 308. The sub-order of 
fresh water and land Turtles, Amydse, p. 310. 
Section 19. Conclusions. - Ordinal characters are essen- 
tially anatomical characters, and not what are com- 
monly called zoological characters, p. 313. TABLE OF CONTENTS. 
XLIX 
CHAPTER II. 
THE FAMILIES OF TESTUDINATA. 
Section 1. General remarks upon families.- The method 
generally adopted in limiting families is defective. To 
arrive at satisfactory results, it is necessary to ascertain 
by careful comparisons what are the structural elements 
which constitute the different patterns of the families, 
p. 317-320. 
Section 2. The family of Sphargididee, p. 320. 
Section 3. The family of Chelonioidce, p. 324. 
Section 4. The family of Trionychidce, p. 329. 
Section 5. The family of Chelyoidce, p. 335. The Ster- 
notheroidae, Pelomedusae, Hydraspides, Chelodinoidae, 
and Podocnemides, note, p. 339. 
Section 6. The family of Chelydroidce, p. 341. 
Section 7. The family of Cinosternoidce, p. 346. 
Sections. The family of Emydoidce,p. 351. Sub-families: 
Nectemydoidae, Deirochelyoidte, Evemydoidae, Clemmy- 
doidae, Cistudinina, p. 355-356. 
Section 9. The family of Testudinina, p. 356. 
Section 10. On the brain of the different families of North 
American Turtles. The brain is typical for different 
families among Vertebrata. p. 362. 
Section 11. Differences in the mode of life of Testudinata. 
The natural limits of families do not always coincide 
with the mode of life of their representatives, p. 365. 
CHAPTER III 
NORTH AMERICAN GENERA AND SPECIES OF TESTUDINATA. 
Section 1. General remarks upon the North American 
genera and species of Testudinata. - How the genera 
of Testudinata ought to be characterized, and how they 
compare with genera in other classes, p. 367. 
Section 2. The genus Sphargis, p. 371. Sphargis coria- 
cea, p. 373. Identification and range of distribution of 
the species, p. 373. w 
Section 3. The genera and species of Chelonioidce, p. 375. 
Chelonia, p. 377. Chelonia My das, p. 378. Chelonia 
virgata, p. 379. Eretmochelys, p. 380. Eretmochelys 
imbricata, p. 381. Eretmochelys squamata, p. 382. 
Thalassochelys, p. 383. Thalassochelys Caouana, p. 
384. 
Section 4. Comparison of the growth of the Chelonii with 
that of the Amydce, p. 386. 
Section 5. The genera of Trionychidce, p. 394. Amyda, 
p. 398. Amyda mutica, p. 399. Platypeltis, p. 400. 
Platypeltis ferox, p. 401. Aspidonectes, p. 403. Aspi- 
donectes spinifer, p. 403. Aspidonectes asper, p. 405. 
Aspidonectes nuchalis, p. 406. Aspidonectes Emoryi, 
p. 407. 
Section 6. The genera of Chelydroidce, p. 409. Gypo- 
chelys, p. 413. Gypochelys lacertina, p. 414. Chely- 
dra, p. 416. Chelydra serpentina, p. 417. 
Section 7. The genera of Cinosternoidce, p. 418. Sub- 
family of Ozothecoidae, p. 423. Goniochelys, p. 423. 
Goniochelys triquetra, p. 423. Goniochelys minor, p. 
424. Ozotheca, p. 424. Ozotheca odorata, p. 425. 
Ozotheca tristycha, p. 425. Sub-family of Cinoster- 
noidae, p. 426. Cinosternum, p. 426. Thyrosternum, 
p. 427. Thyrosternum pennsylvanicum, p. 428. Thy- 
rosternum sonoriense, p. 428. Thyrosternum integrum, 
p. 429. Platythyra, p. 429. Platythyra flavescens, 
p. 430. 
Section 8. The genera of Emydoidce, p. 430. Sub-family 
of Nectemydoidae, p. 431. Ptychemys, p. 431. Pty- 
chemys rugosa, p. 431. Ptychemys concinna, p. 432. 
Ptychemys mobiliensis, p. 433. Ptychemys hieroglyph- 
ica, p. 434. Ptychemys decussata, p. 434. Trachemys, 
p. 434. Trachemys scabra, p. 434. Trachemys Troos- 
tii, p. 435. Trachemys elegans, p. 435. Trachemys 
rugosa, p. 436. Graptemys, p. 436. Graptemys geo- 
graphica, p. 436. Graptemys LeSueurii, p. 436. Mala- 
coclemmys, p. 437. Malacoclemmys palustris, p. 437. L 
TABLE OF CONTENTS. 
Chrysemys, p. 438. Chrysemys picta, p. 438. Chry- 
semys marginata, p. 439. Chrysemys Bellii, p. 439. 
Chrysemys oregonensis, p. 440. Chrysemys dorsalis, p. 
440. Sub-family of Deirochelyoidae, Deirochelys re- 
ticulata, p. 441. Sub-family Evemydoidae, and genus 
Emys, p. 441. Emys Meleagris, p. 442. Sub-family 
of Clemmydoidae, p. 442. Nanemys guttata, p. 442. 
Calemys Miihlenbergii, p. 443. Glyptemys insculpta, 
p. 443. Actinemys marmorata, p. 144. Sub-family of 
Cistudinina, p. 444. Cistudo, p. 444. Cistudo vir- 
ginea, triunguis, ornata, and major, p. 445. 
Section 9. The genera of Testudinina, p. 446. Xerobates, 
p.446. Xerobates carolinus, 447. Xerobates Berlandieri, 
p. 447. Fossil Testudinina, p. 448. Chelonoidis, p. 
448. Megalochelys, p. 448. Testudo proper, Chersus, 
and Psammobates, p. 449. 
Section 10. Chelonian Faunae of North America, p. 449. 
Our Turtles belong to seven different Faunae. 
PART III. 
EMBRYOLOGY OF THE TURTLE. 
CHAPTER I. 
DEVELOPMENT OF THE EGG, FROM ITS FIRST APPEARANCE TO THE FORMATION OF THE 
EMBRYO. 
Section 1. The origin of the egg. Precautions taken 
in the investigation. The egg originates between the 
cells of the stroma. Initial form of the egg. Forma- 
tion of the germinal vesicle, p. 451-457. 
Section 2. Development of the yolk. Successive stages 
in the development of the yolk; its constitution and 
changes at different periods. It contains at first only 
granules, and no cells, p. 458. 
Section 3. Development of the yolk cells. Probably con- 
nected with the first influence of copulation. Mode 
of formation of yolk cells. Their cell wall or ecto- 
blast, p. 463. Formation of the mesoblast, p. 467. 
Formation of the entoblast, p. 472. 
Section 4. The Purkinjean Vesicle. - It originates in an 
eccentric position, p. 475. Its successive changes, p. 
476. The Wagnerian vesicles, p. 476. 
Section 5. The growth of the ovarian egg as a whole. - 
Dissimilarity between its two sides, one of which corre- 
sponds to the position of the Purkinjean vesicle, and the 
other to the opposite portion of the egg. This antago- 
nism is carried out further during the whole life of the 
growing animal. The ovarian egg is in fact the animal 
itself in its first stage of development, p. 479-482. 
Section 6. The Graafian follicle and the membranes of 
the egg. - The stroma, p. 482. The tunica granulosa, 
p. 483. The zona pellucida, p. 484. The vitelline sac, 
p. 485. The embryonal membrane, p. 486. 
Section 7. Fecundation. - The act of fecundation is suc- 
cessive in Turtles. From the first copulation to the 
time of laying, there elapse four years, during which 
eight copulations take place. The eggs grow for a long 
time before they are fecundated, p. 489-492. TABLE OF CONTENTS. 
LI 
CHAPTER II 
DEVELOPMENT OF THE EMBRYO FROM THE TIME THE EGG LEAVES THE OVARY TO THAT OF 
THE HATCHING OF THE YOUNG. 
Section 1. The laying of the eggs. - Importance of local 
information respecting the habits of animals. The in- 
habitants of the country have much knowledge upon 
this subject that is not yet recorded. Period of laying. 
Passage of the eggs through the oviduct. Turtles lay 
only once a year. p. 493-501. 
Section 2. Deposition of the albumen and formation of the 
shell. - The albumen and shell membrane, p. 501-507. 
The shell, p. 508. 
Section 3. The absorption of albumen into the yolk sac.- 
The albumen is gradually absorbed into the yolk sac, 
p. 511-513. This also takes place in birds' eggs, p. 
513. 
Section 4. The transformations of the yolk in the fecun- 
dated egg. - Enlargement of the mesoblast, p. 516. 
Sudden multiplication of the entoblasts, p. 517. Seg- 
mentation of the mesoblast, p. 517. It results in the 
formation of the primitive cellular basis of the germ, 
p. 522. 
Section 5. Segmentation of the yolk. - The segmentation 
of the yolk takes place during the passage of the egg 
through the oviduct. The embryonic disc and the 
germinal layer, p. 523-528. 
Section 6. The whole egg is the embryo. - There is no 
natural limit between the development of the embryo, 
from its first appearance as egg to the formation of a 
distinct germ, and its ultimate growth. Continuity of 
the genetic process, p. 528-534. 
Section 7. Foldings of the embryonic disc, and successive 
stages of growth of the Turtle. - The embryonic disc, 
p. 535. The amnios, p. 536. Growth of the embryo, 
p. 542-578. 
Section 8. Formation and development of the organs.- 
The brain, p. 579. The chorda dorsalis, p. 584. The 
eye, p. 584. The ear, p. 590. The nostrils, p. 591. 
The vertebral column, p. 591. The skull, p. 592. 
The shield, p. 592. The limbs, p. 593. The heart, p. 
594. The bloodvessels, p. 597. The intestine, p. 600. 
Section 9. Histology. - The amnios, p. 602. The spinal 
marrow, p. 602. The medulla oblongata, p. 602. The 
hemispheres, p. 602. The olfactory lobes, p. 603. The 
olfactory nerve, p. 603. The Schneiderian membrane, 
p. 604. The pia mater, p. 604. The chorda dorsalis, 
p. 604. The vertebra?, p. 605. The ribs, p. 606. The 
limbs, p. 607. The skin, p. 608. The eye, p. 609. 
The ear, p. 611. The intestine, p. 611. The allantois, 
p. 613. The urinary bladder, p. 614. The lungs, p. 
614. The trachea, p. 615. The liver, p. 615. The 
gall cyst, p. 615. The bloodvessels, p. 615. The gen- 
ital organs, p. 615. The kidneys, p. 615. The Wolf- 
fian bodies, p. 616. The blood, p. 616. The muscles, 
p. 617. The tendons, p. 618. 
Section 10. Chronology of the development of the embryo. 
From the first segmentation of the yolk to the period 
of hatching, we trace thirty-one stages of development, 
p. 618-622. 
Explanation of the Plates, p. 623-640. 
Appendix and Erkata, p. 641. PART I. 
ESSAY ON CLASSIFICATION. ESSAY ON CLASSIFICATION. 
CHAPTER FIRST. 
THE FUNDAMENTAL RELATIONS OF ANIMALS TO ONE ANOTHER AND TO THE 
WORLD IN WHICH THEY LIVE, AS THE BASIS OF THE NATURAL SYSTEM OF 
ANIMALS. 
SECTION I. 
THE LEADING FEATURES OF A NATURAL ZOOLOGICAL SYSTEM ARE ALL FOUNDED 
IN NATURE. 
Modern classifications of animals and plants are based upon the peculiarities of 
their structure; and this is generally considered as the most important, if not the 
only safe, guide in our attempts to determine the natural relations which exist 
between animals. This view of the subject seems to me, however, to circumscribe 
the foundation of a natural system of Zoology and Botany within too narrow limits, 
to exclude from our consideration some of the most striking characteristics of the 
two organic kingdoms of nature, and to leave it doubtful how far the arrangement 
thus obtained is founded in reality, and how far it is merely the expression of our 
estimate of these structural differences. It has appeared to me appropriate, therefore, 
to present here a short exposition of the leading features of the animal kingdom, as 
an introduction to the embryology of the Chelonians,-one of the most extraordinary 
types among Vertebrata, - as it would afford a desirable opportunity of establishing 
a standard of comparison between the changes animals undergo during their growth, 
and the permanent characters of full-grown individuals of other types, and, perhaps, 
of showing also what other points beside structure might with advantage be consid- 4 
ESSAY ON CLASSIFICATION. 
Part I. 
ered in ascertaining the manifold relations of animals to one another and to the 
world in which they live, upon which the natural system may be founded. 
In considering these various topics, I shall of necessity have to discuss many 
questions bearing upon the very origin of organized beings, and to touch upon many 
points now under discussion among scientific men. I shall, however, avoid contro- 
versy as much as possible, and only try to render the results of my own studies and 
meditations in as clear a manner as I possibly can in the short space that I feel 
justified in devoting to this subject in this volume. 
There is no question in Natural History on which more diversified opinions are 
entertained than on that of Classification; not that naturalists disagree as to the 
necessity of some sort of arrangement in describing animals or plants, for since 
nature has become the object of special studies, it has been the universal aim of all 
naturalists to arrange the objects of their investigations in the most natural order 
possible. Even Buffon, who began the publication of his great Natural History 
by denying the existence in nature of any thing like a system, closed his work by 
grouping the birds according to certain general features, exhibited in common by 
many of them. It is true, authors have differed in their estimation of the characters 
on which their different arrangements are founded; and it is equally true that they 
have not viewed their arrangements in the same light, some having plainly acknowl- 
edged the artificial character of their systems, while others have urged theirs as the 
true expression of the natural relations which exist between the objects themselves. 
But, whether systems were presented as artificial or natural, they have, to this day, 
been considered generally as the expression of man's understanding of natural objects, 
and not as a system devised by the Supreme Intelligence, and manifested in these 
objects.1 
There is only one point in these innumerable systems on which all seem to meet, 
namely, the existence in nature of distinct species, persisting with all their pecul- 
iarities, for a time at least; for even the immutability of species has been ques- 
tioned.2 Beyond species, however, this confidence in the existence of the divis- 
ions, generally admitted in zoological systems, diminishes greatly. 
With respect to genera, we find already the number of the naturalists who 
1 The expressions constantly used with refer- 
ence to genera and species and the higher groups 
in our systems, - as, Mr. A. has made such a species 
a genus ; Mr. B. employs this or that species to form 
his genus; and in which most naturalists indulge 
when speaking of their species, their genera, their 
families, their systems, - exhibit in an unquestiona- 
ble light the conviction, that such groups are of their 
own making; which can, however, only be true in so 
far as these groups are not true to nature, if the 
views I shall present below are at all correct. 
2 Lamarck (J. B. de) Philosophic zoologique, 
Paris, 1809, 2 vols. 8vo.; 2de edit., 1830. - Powell 
(The Rev. Baden) Essays on the Spirit of the In- 
ductive Philosophy, etc., London, 1855, 1 vol. 8vo. 
Compare, also, Sect. 15, below. Chap. I. 
FUNDAMENTAL RELATIONS OF ANIMALS. 
5 
accept them as natural divisions much smaller ; few of them having expressed a 
belief that genera have as distinct an existence in nature as species. And as to 
families, orders, classes, or any kind of higher divisions, they seem to be universally 
considered as convenient devices, framed with the view of facilitating the study of 
innumerable objects, and of grouping them in the most suitable manner. The indif- 
ference wTith which this part of our science is generally treated becomes unjustifiable, 
considering the progress which Zoology in general has made of late. It is a matter 
of consequence, whether genera are circumscribed in our systematic works within 
these or those limits; whether families inclose a wider or more contracted range of 
genera; whether such or such orders are admitted in a class, and what are the natu- 
ral boundaries of classes; as well as how the classes themselves are related to one 
another, and whether all these groups are considered as resting upon the same foun- 
dation in nature or not. 
Without venturing here upon an analysis of the various systems of Zoology,-the 
prominent features of which are sufficiently exemplified for my purpose by the sys- 
tems of Linnaeus and Cuvier,1 which must be familiar to every student of Natural 
History, - it is certainly a seasonable question to ask, whether the animal kingdom 
exhibits only those few subdivisions into orders and genera which the Linnaean 
system indicates, or whether the classes differ among themselves to the extent which 
the system of Cuvier would lead us to suppose. Or is, after all, this complicated 
structure of Classification merely an ingenious human invention, which every one may 
shape, as he pleases, to suit himself? When we remember that all the works on Nat- 
ural History admit some system or other of this kind, it is certainly an aim wor- 
thy of a true naturalist, to ascertain what is the real meaning of all these divisions. 
Embryology, moreover, forces the inquiry upon us at every step, as it is impos- 
sible to establish precise comparisons between the different stages of growth of young 
animals of any higher group and the permanent characters of full-grown individuals 
of other types, without first ascertaining what is the value of the divisions with 
which we may have to compare embryos. This is my reason for introducing here, 
in a work chiefly devoted to Embryology, a subject to. which I have paid the most 
careful attention for many years past, and for the solution of which I have made 
special investigations. 
Before I proceed any further, however, I would submit one case to the consider- 
ation of my reader. Suppose that the innumerable articulated animals, which are 
counted by tens of thousands, nay, perhaps by hundreds of thousands, had never 
made their appearance upon the surface of our globe, with one single exception : 
that, for instance, our Lobster (Homarus americanus) were the only representative of 
1 Compare Chap. III. 6 
ESSAY ON CLASSIFICATION. 
Part 1. 
that extraordinarily diversified type,-how should we introduce that species of animals 
in our systems? Simply as a genus with one species, by the side of all the other 
classes with their orders, families, etc., or as a family containing only one genus with 
one species, or as a class with one order and one genus, or as a class with one 
family and one genus? And should we acknowledge, by the side of Vertebrata, 
Mollusks, and Radiata, another type of Articulata, on account of the existence of 
that one Lobster, or would it be natural to call him by a single name, simply as a 
species, in contradistinction to all other animals ? It was the consideration of this 
supposed case which led me to the investigations detailed below, which, I hope, may 
end in the ultimate solution of this apparently inextricable question. 
Though what I have now to say about this supposed case cannot be fully appre- 
ciated before reading my remarks in the following chapter,1 respecting the character 
of the different kinds of groups adopted in our systems, it must be obvious that our 
Lobster, to be what we see these animals are, must have its frame constructed upon 
that very same plan of structure which it exhibits now; and, if I should succeed in 
showing that there is a difference between the conception of a plan and the manner 
of its execution, upon which classes are founded in contradistinction to the types to 
which they belong, we might arrive at this distinction by a careful investigation of 
that single Articulate, as well as by the study of all of them; and we might then 
recognize its types and ascertain its class characters as fully as if the type embraced 
several classes, and this class thousands of species. Then that animal has a form, 
which no one would fail to recognize; so that, if form can be shown to be charac- 
teristic of families, we could thus determine its family. Again: besides the general 
structure, showing the fundamental relations of all the systems of organs of the 
body to one another in their natural development, our investigation could be carried 
into the study of the details of that structure in every part, and thus lead to the 
recognition of what constitutes everywhere generic characters. Finally: as this ani- 
mal has definite relations to the surrounding world, as the individuals living at the 
time bear definite relations to one another, as the parts of their body show definite 
proportions, and as the surface of the body exhibits a special ornamentation, the spe- 
cific characters could be traced as fully as if a number of other species were at hand 
for comparison; and they might be drawn and described with sufficient accuracy to 
distinguish it at any future time from any other set of species found afterwards, how- 
ever closely these new species might' be allied to it. In this case, then, we should 
have to acknowledge a separate branch in the animal kingdom, with a class, a family, 
and a genus, to introduce one species to its proper place in the system of animals. 
But the class would have no order, if orders determine the rank, as ascertained by 
1 See Chap. IL Chap. I. 
FUNDAMENTAL RELATIONS OF ANIMALS. 
7 
the complication of structure; for, where there is but one representative of a type, 
there is no room for the question of its superiority or inferiority in comparison to 
others within the limits of the class, orders being groups subordinate to one another 
in their class. Yet, even in this case, the question of the standing of Articulata, as a 
type among the other great branches of the animal kingdom, would be open to our 
investigations; but it would assume another aspect from that which it now presents, 
as the comparison of Articulata with the other types would then be limited to the 
Lobster, and would lead to a very different result from that to which we may arrive, 
now that this type includes such a large number of most extensively diversified rep- 
resentatives, belonging even to different classes. That such speculations are not idle 
must be apparent to any one wTho is aware, that, during every period in the history 
of our globe in past geological ages,1 the general relations, the numeric proportions, 
and the relative importance of all the types of the animal kingdom, have been ever 
changing, until their present relations were established. Here, then, the individuals 
of one species, as observed while living, simultaneously exhibit characters, which, to 
be expressed satisfactorily and in conformity to what nature tells us, would require 
the establishment, not only of a distinct species, but also of a distinct genus, a dis- 
tinct family, a distinct class, a distinct branch. Is not this in itself evidence enough 
that genera, families, orders, classes, and types have the same foundation in nature as 
species, and that the individuals living at the time have alone a material existence, 
they being the bearers, not only of all these different categories of structure upon 
which the natural system of animals is founded, but also of all the relations which 
animals sustain to the surrounding world,-thus showing that species do not exist in 
nature in a different way from the higher groups, as is so generally believed? 
The divisions of animals according to branch, class, order, family, genus, and 
species, by wThich we express the results of our investigations into the relations of 
the animal kingdom, and which constitute the first question respecting the scientific 
systems of Natural History which we have to consider, seem to me to deserve the 
consideration of all thoughtful minds. Are these divisions artificial or natural? Are 
1 A series of classifications of animals and plants, 
exhibiting each a natural system of the types known 
to have existed simultaneously during the several 
successive geological periods, considered singly and 
without reference to the types of other ages, would 
show in a strong light the different relations in 
which the classes, the' orders, the families, and even 
the genera and species, have stood to one another 
during each epoch. Such classifications would illus- 
trate, in the most impressive manner, the importance 
of an accurate knowledge of the relative standing 
of all animals and plants, which can only be inferred 
from the perusal even of those palaeontological works 
in which fossil remains are illustrated according to 
their association in different geological formations ; 
for, in all these works, the remains of past ages are 
uniformly referred to a system established upon the 
study of the animals now living, thus lessening the 
impression of their peculiar combination for the 
periods under consideration. 8 
ESSAY ON CLASSIFICATION. 
Part I. 
they the devices of the human mind to classify and arrange our knowledge in such 
a manner as to bring it more readily within our grasp and facilitate further investi- 
gations, or have they been instituted by the Divine Intelligence as the categories of 
his mode of thinking ?1 Have we, perhaps, thus far been only the unconscious 
interpreters of a Divine conception, in our attempts to expound nature? and when, 
in our pride of philosophy, we thought that we were inventing systems of science 
and classifying creation by the force of our own reason, have we followed only, and 
reproduced, in our imperfect expressions, the plan whose foundations were laid in the 
dawn of creation, and the development of which we are laboriously studying,-think- 
ing, as we put together and arrange our fragmentary knowledge, that we are anew 
introducing order into chaos? Is this order the result of the exertions of human skill 
and ingenuity, or is it inherent in the objects themselves, so that the intelligent stu- 
dent of Natural History is led unconsciously, by the study of the animal kingdom 
itself, to these conclusions, the great divisions under which he arranges animals being 
indeed but the headings to the chapters of the great book which he is reading? To 
me it appears indisputable, that this order and arrangement of our studies are based 
upon the natural, primitive relations of animal life,-those systems, to which we have 
given the names of the great leaders of our science who first proposed them, being 
in truth but translations, into human language, of the thoughts of the Creator. And 
if this is indeed so, do we not find in this adaptability of the human intellect to the 
facts of creation, by which we become instinctively, and, as I have said, unconsciously, 
the translators of the thoughts of God, the most conclusive proof of our affinity with 
the Divine Mind? and is not this intellectual and spiritual connection with the Almighty 
worthy our deepest consideration ? If there is any truth in the belief that man is 
made in the image of God, it is surely not amiss for the philosopher to endeavor, by 
the study of his own mental operations, to approximate the workings of the Divine 
Reason, learning, from the nature of his own mind, better to understand the Infinite 
Intellect from which it is derived. Such a suggestion may, at first sight, appear irrev- 
erent. But, which is the truly humble? He who, penetrating into the secrets of cre- 
ation, arranges them under a formula which he proudly calls his scientific system? or 
he who, in the same pursuit, recognizes his glorious affinity with the Creator, and, in 
deepest gratitude for so sublime a birthright, strives to be the faithful interpreter of 
that Divine Intellect with whom he is permitted, nay, with whom he is intended, 
according to the laws of his being, to enter into communion ? 
1 It must not be overlooked here that a system 
may be natural, that is, may agree in every respect 
with the facts in nature, and yet not be considered 
by its author as the manifestation of the thoughts 
of a Creator, but merely as the expression of a 
fact existing in nature, no matter how, which the 
human mind may trace and reproduce in a system- 
atic form of its own invention. Chap. I. 
FUNDAMENTAL RELATIONS OF ANIMALS. 
9 
I confess that this question as to the nature and foundation of our scientific 
classifications appears to me to have the deepest importance, an importance far greater 
indeed than is usually attached to it. If it can be proved that man has not 
invented, but only traced this systematic arrangement in nature, that these relations 
and proportions which exist throughout the animal and vegetable world have an 
intellectual, an ideal connection in the mind of the Creator, that this plan of crea- 
tion, which so commends itself to our highest wisdom, has not grown out of the 
necessary action of physical laws, but was the free conception of the Almighty 
Intellect, matured in his thought, before it was manifested in tangible external forms, 
-if, in short, we can prove premeditation prior to the act of creation, we have done, 
once and for ever, with the desolate theory which refers us to the laws of matter as 
accounting for all the wonders of the universe, and leaves us with no God but the 
monotonous, unvarying action of physical forces, binding all things to their inevitable 
destiny.1 I think our science has now reached that degree of advancement, in which 
we may venture upon such an investigation. 
The argument for the existence of an intelligent Creator is generally drawn from 
1 I allude here only to the doctrines of material- 
ists ; but I feel it necessary to add, that there are 
physicists, who might be shocked at the idea of being 
considered as materialists, who are yet prone to be- 
lieve that when they have recognized the laws which 
regulate the physical world, and acknowledged that 
these laws were established by the Deity, they have 
explained every thing, even when they have consid- 
ered only the phenomena of the inorganic world, as 
if the world contained no living beings and as if 
these living beings exhibited nothing that differed 
from the inorganic world. Mistaking for a causal 
relation the intellectual connection observable be- 
tween serial phenomena, they are unable to perceive 
any difference between disorder and the free, inde- 
pendent, and self-possessed action of a superior mind, 
and call mysticism, even a passing allusion to the 
existence of an immaterial principle in animals, which 
they acknowledge themselves in man. [Powell's 
Essays, etc., p. 478, 385, and 466.] I would further 
remark, that, when speaking of creation in contra- 
distinction with reproduction, I mean only to allude 
to the difference there is between the regular course 
of phenomena in nature and the establishment of that 
order of things, without attempting to explain either; 
for in whatever manner any state of things which 
has prevailed for a time upon earth may have been 
introduced, it is self-evident that its establishment 
and its maintenance for a determined period are two 
very different things, however frequently they may 
be mistaken as identical. It is further of itself plain 
that the laws which may explain the phenomena of 
the material world, in contradistinction from the or- 
ganic, cannot be considered as accounting for the 
existence of living beings, even though these have a 
material body, unless it be actually shown that the 
action of these laws implies by their very nature the 
production of such beings. Thus far, Cross's experi- 
ments are the only ones offered as proving such a 
result. I do not know what physicists may think 
about them now ; but I know that there is scarcely 
a zoologist who doubts that they only exhibited a 
mistake. Life in appropriating the physical world 
to itself with all its peculiar phenomena exhibits, how- 
ever, some of its own and of a higher order, which 
cannot be explained by physical agencies. The cir- 
cumstance that life is so deeply rooted in the inor- 
ganic nature, affords, nevertheless, a strong tempta- 
tion to explain one by the other; but we shall see 
presently how fallacious these attempts have been. 10 
ESSAY ON CLASSIFICATION. 
Part I. 
the adaptation of means to ends, upon which the Bridgewater treatises, for example, 
have been based.1 But this does not appear to me to cover the whole ground, for 
we can conceive that the natural action of objects upon each other should result in 
a final fitness of the universe, and thus produce an harmonious whole; nor does 
the argument derived from the connection of organs and functions seem to me more 
satisfactory, for, beyond certain limits, it is not even true. We find organs without 
functions, as, for instance, the teeth of the whale, which never cut through the gum, 
the breast in all males of the class of mammalia; these and similar organs are pre- 
served in obedience to a certain uniformity of fundamental structure, true to the 
original formula of that division of animal life, even when not essential to its mode 
of existence. The organ remains, not for the performance of a function, but with 
reference to a plan,2 and might almost remind us of what we often see in human 
structures, when, for instance, in architecture, the same external combinations are 
retained for the sake of symmetry and harmony of proportion, even when they have 
no practical object. 
1 disclaim every intention of introducing in this work any evidence irrelevant to 
my subject, or of supporting any conclusions not immediately flowing from it; but 1 
cannot overlook nor disregard here the close connection there is between the facts 
ascertained by scientific investigations, and the discussions now carried on respecting 
the origin of organized beings. And though I know those who hold it to be very 
unscientific to believe that thinking; is not something; inherent in matter, and that 
there is an essential difference between inorganic and living and thinking beings, I 
shall not be prevented by any such pretensions of a false philosophy from expressing 
1 The Bridgewater Treatises, on the Power, Wis- 
dom, and Goodness of God, as Manifested in the 
Creation : Chalmers, (Thomas,) The Adaptation of 
External Nature to the Moral and Intellectual Consti- 
tution of Man, Glasgow, 1839, 2 vols. 8vo. - Kidd, 
(John,) On the Adaptation of External Nature to 
the Physical Condition of Man, London, 1833, 1 vol. 
8vo. - Whewell, (Will.,) Astronomy and General 
Physics considered with Reference to Natural Theol- 
ogy, London, 1839, 1 vol. 8vo. - Bell, (Charles,) 
The Hand, its* Mechanism and Vital Endowments, as 
evincing Design, London, 1833, 1 vol. 8vo. - Roget, 
(Peter Mark,) Animal and Vegetable Physiology, 
considered with Reference to Natural Theology, Lon- 
don, 1834, 2 vols. 8vo. - Buckland, (Will.,) Ge- 
ology and Mineralogy considered with Reference to 
Natural Theology, London, 1836, 2 vols. 8vo.; 2d 
edit. 1837. - Kirby, (Will.,) The Power, Wisdom, 
and Goodness of God, as Manifested in the Creation 
of Animals, and in their History, Habits, and Instincts, 
London, 1835, 2 vols. 8vo. - Prout, (Will.,) Chem- 
istry, Meteorology, and the Function of Digestion, 
considered with Reference to Natural Theology, Lon- 
don, 1834, 1 vol. 8vo. Compare also: Strauss- 
Durkheim, (Hero.,) Theologie de la Nature, Paris, 
1852, 3 vols. 8vo. - Miller, (Hugh,) Footprints of 
the Creator, Edinburgh, 1849, 1 vol. 12mo. - Bab- 
bage, (C.,) The Ninth Bridgewater Treatise, a Frag- 
ment, London, 1838, 1 vol. 8vo. ; 2d edit. 
2 The unity of structure of the limbs of club- 
footed or pinnated animals, in which the fingers are 
never moved, with those which enjoy the most per- 
fect articulations and freedom of motion, exhibits this 
reference most fully. Chap. I. 
FUNDAMENTAL RELATIONS OF ANIMALS. 
11 
my conviction that as long as it cannot be shown that matter or physical forces do 
actually reason, I shall consider any manifestation of thought as evidence of the 
existence of a thinking being as the author of such thought, and shall look upon an 
intelligent and intelligible connection between the facts of nature as direct proof of 
the existence of a thinking God,1 as certainly as man exhibits the power of thinking 
when he recognizes their natural relations. 
As I am not writing a didactic work, I will not enter here into a detailed illus- 
tration of the facts relating to the various subjects submitted to the consideration of 
my reader, beyond what is absolutely necessary to follow the argument, nor dwell at 
any length upon the conclusions to which they lead, but simply recall the leading 
features of the evidence, assuming in the argument a full acquaintance with the 
whole range of data upon which it is founded^ whether derived from the affinities or 
the anatomical structure of animals, or from their habits and their geographical distri- 
bution, from their embryology, or from their succession in past geological ages, and 
the peculiarities they have exhibited during each,2 believing, as I do, that isolated and 
disconnected facts are of little consequence in the contemplation of the whole plan 
1 I am well aware that even the most eminent 
investigators consider the task of science at an end, 
as soon as the most general relations of natural phe- 
nomena have been ascertained. To many the in- 
quiry into the primitive cause of their existence 
seems either beyond the reach of man, or as be- 
longing rather to philosophy than to physics. To 
these the name of God appears out of place in a 
scientific work, as if the knowledge of secondary 
agencies constituted alone a worthy subject for their 
investigations, and as if nature could teach nothing 
about its Author. Many, again, are no doubt pre- 
vented from expressing their conviction that the 
world was called into existence and is regulated by 
an intelligent God, either by the fear of being sup- 
posed to share clerical or sectarian prejudices; or 
because it may be dangerous for them to discuss 
freely such questions without acknowledging at the 
same time the obligation of taking the Old Testament 
as the standard by which the validity of their re- 
sults is to be measured. Science, however, can only 
prosper when confining itself within its legitimate 
sphere; and nothing can be more detrimental to its 
true dignity than discussions like those which took 
place at the last meeting of the German association 
of naturalists, in Gottingen, and which have since 
then been carried on in several pamphlets in which 
bigotry vies with personality and invective. 
2 Many points little investigated thus far by most 
naturalists, but to which I have of late years paid 
particular attention, are here presented only in an 
aphoristic form, as results established by extensive 
investigations, though unpublished, most of which will 
be fully illustrated in my following volumes, or in a 
special work upon the plan of the creation. (See 
Agassiz, (L.,) On the Difference between Progres- 
sive, Embryonic, and Prophetic Types in the Succes- 
sion of Organized Beings, Proceed. 2d Meeting Amer. 
Assoc, for the Advancement of Science, held at Cam- 
bridge in 1849, Boston, 1850, 1 vol. 8vo., p. 432.) 
Meanwhile I refer in foot notes to such works as con- 
tain the materials already on hand for the discussion 
of these subjects, even when presented in a different 
light. I would only beg leave to add, that in these 
references I have by no means attempted to quote all 
the writers upon the various topics under consider- 
ation, but only the most prominent and most instruc- 
tive, and here and there some condensed accounts 
of the facts in more elementary works, by the side 
of the original papers. 12 
ESSAY ON CLASSIFICATION. 
Part I. 
of creation, and that without a consideration of all the facts furnished by the study 
of the habits of animals, by their anatomy, their embryology, and the history of the 
past ages of our globe, we shall never arrive at the knowledge of the natural system 
of animals. 
Let us now consider some of these topics more specially. 
SECTION II. 
SIMULTANEOUS EXISTENCE OF THE MOST DIVERSIFIED TYPES UNDER IDENTICAL 
CIRCUMSTANCES. 
It is a fact which seems to be entirely overlooked by those who assume an exten- 
sive influence of physical causes upon the very existence of organized beings, that 
the most diversified types of animals and plants are everywhere found under iden- 
tical circumstances. The smallest sheet of fresh water, every point upon the sea- 
shore, every acre of dry land, teems with a variety of animals and plants. The 
narrower the boundaries are, which may be assigned as the primitive home of all 
these beings, the more uniform must be the conditions under which they are assumed 
to have originated; so uniform, indeed, that in the end the inference would be, that 
the same physical causes could produce the most diversified effects.1 To concede, 
1 In order fully to appreciate the difficulty al- 
luded to here, it is only necessary to remember how 
complicated, and at the same time how localized the 
conditions are under which animals multiply. The 
egg originates in a special organ, the ovary; it grows 
there to a certain size, until it requires fecundation, 
that is, the influence of another living being, or at 
least of the product of another organ, the spermary, 
to determine the further development of the germ, 
which, under the most diversified conditions, in dif- 
ferent species, passes successively through all those 
changes which lead to the formation of a new per- 
fect being. I then would ask, is it probable that 
the circumstances under which animals and plants 
originated for the first time can be much simpler, 
or even as simple, as the conditions necessary for 
their reproduction only, after they have once been 
created ? Preliminary, then, to their first appearance, 
the conditions necessary for their growth must have 
been provided for, if, as I believe, they were crea- 
ted as eggs, which conditions must have been con- 
formable to those in which the living representatives 
of the types first produced, now reproduce them- 
selves. If it were assumed that they originated in 
a more advanced stage of life, the difficulties would 
be still greater, as a moment's consideration cannot 
fail to show, especially if it is remembered how com- 
plicated the structure of some of the animals was, 
which are known to have been among the first in- 
habitants of our globe. When investigating this sub- 
ject, it is of course necessary to consider the first 
appearance of animals and plants, upon the basis of 
probabilities only, or even simply upon that of pos- 
sibilities ; as with reference to these first-born, at 
least, the transmutation theory furnishes no explana- 
tion of their existence. 
For every species belonging to the first fauna ami 
the first flora which have existed upon earth, special Chap. I. 
DIVERSIFIED TYPES FOUND EVERYWHERE. 
13 
on the contrary, that these organisms may have appeared in the beginning over a 
wide area, is to grant, at the same time, that the physical influences under which 
they existed at first were not so specific as to justify the assumption that these could 
be the cause of their appearance. In whatever connection, then, the first appear- 
ance of organized beings upon earth is viewed, whether it is assumed that they 
originated within the most limited areas, or over the widest range of their present 
natural geographical distribution, animals and plants being everywhere diversified to 
the most extraordinary extent, it is plain that the physical influences under which 
they subsist cannot logically be considered as the cause of that diversity. In this, 
as in every other respect, when considering the relations of animals and plants to 
the conditions under which they live, or to one another, we are inevitably led to 
look beyond the material facts of the case for an explanation of their existence. 
Those who have taken another view of this subject, have mistaken the action and 
reaction which exist everywhere between organized beings, and the physical influences 
under which they live1 for a causal or genetic connection, and carried their mistake 
so far as to assert that these manifold influences could really extend to the production 
of these beings, not considering how inadequate such a cause would be, and that 
even the action of physical agents upon organized beings presupposes the very exist- 
ence of those beings.2 The simple fact that there has been a period in the history 
relations, special contrivances must therefore have 
been provided. Now, what would be appropriate 
for the one, would not suit the other, so that exclud- 
ing one another in this way, they cannot have origi- 
nated upon the same point; while within a wider 
area, physical agents are too uniform in their mode 
of action to have laid the foundation for so many 
such specific differences as existed between the first 
inhabitants of our globe. 
1 See, below, Sect. 16. 
2 A critical examination of this point may dis- 
pel much of the confusion which prevails in the dis- 
cussions relating to the influence of physical causes 
upon organized beings. That there exist definite 
relations between animals as well as plants and the 
mediums in which they live, no one at all familiar 
with the phenomena of the organic world can doubt; 
that these mediums and all physical agents at work 
in nature, have a certain influence upon organized 
beings is equally plain. But before any such action 
can take place and be felt, organized beings must 
exist. The problem before us involves, therefore, 
two questions, the influence of physical agents upon 
animals and plants already in existence, and the ori- 
gin of these beings. Granting the influence of these 
agents upon organized beings to the fullest extent 
to which it may be traced, (see Sect. 1G,) there 
remains still the question of their origin upon which 
neither argument nor observation has yet thrown any 
light. But according to some, they originated spon- 
taneously by the immediate agency of physical forces, 
and have become successively more and more diver- 
sified by changes produced gradually upon them, by 
these same forces. Others believe that there exist 
laws in nature which were established by the Deity 
in the beginning, to the action of which the origin 
of organized beings may be ascribed ; while accord- 
ing to others, they owe their existence to the im- 
mediate intervention of an intelligent Creator. It 
is the object of the following paragraphs to show 
that there are neither agents nor laws in nature 
known to physicists under the influence and by the 
action of which these beings could have originated; 
that, on the contrary, the very nature of these be- 14 
ESSAY ON CLASSIFICATION. 
Part I. 
of our earth, now well known to geologists,1 when none of these organized beings as 
yet existed, and when, nevertheless, the material constitution of our globe, and the 
physical forces acting upon it, were essentially the same as they are now,2 shows that 
these influences are insufficient to call into existence any living being. 
Physicists know, indeed, these physical agents more accurately than the naturalists, 
who ascribe to them the origin of organized beings; let us then ask them, whether 
the nature of these agents is not specific, whether their mode of action is not spe- 
cific? They will all answer, that they are. Let us further inquire of them, what 
evidence there is, in the present state of our knowledge, that at any time these 
physical agents have produced any thing they no longer do produce, and what prob- 
ability there is that they may ever have produced any organized being? If 1 am 
not greatly mistaken, the masters in that department of science will, one and all, 
answer, none whatever. 
But the character of the connections between organized beings and the physical 
conditions under which they live is such as to display thought;8 these connections 
are therefore to be considered as established, determined, and regulated by a thinking 
being. They must have been fixed for each species at its beginning, while the fact 
of their permanency through successive generations4 is further evidence that with 
their natural relations to the surrounding world were also determined the relations 
of individuals to one another,6 their generic as well as their family relations, and 
every higher grade of affinity,6 showing, therefore, not only thought, in reference to 
the physical conditions of existence, but such comprehensive thoughts as would 
embrace simultaneously every characteristic of each species. 
Every fact relating to the geographical distribution of animals and plants might 
be alluded to in confirmation of this argument, but especially the character of every 
ings, and their relations to one another and to the 
world in which they live, exhibit thought, and can 
therefore be referred only to the immediate action 
of a thinking being, even though the manner in 
which they were called into existence remains for 
the present a mystery. 
1 Few geologists only may now be inclined to 
believe that the lowest strata known to contain fos- 
sils, are not the lowest deposits formed since the 
existence of organized beings upon earth. But even 
those who would assume that still lower fossiliferous 
beds may yet be discovered, or may have entirely 
disappeared by the influence of plutonic agencies, 
(Powell's Essays, etc., p. 424,) must acknowledge 
the fact that everywhere in the lowest rocks known 
to contain fossils at all, there is a variety of them 
found together. (See Sect. 7.) Moreover, the simi- 
larity in the character of the oldest fossils found in 
different parts of the world, goes far, in my opin- 
ion, to prove that we actually do know the earliest 
types of the animal kingdom which have inhabited 
our globe. This conclusion seems fully sustained by 
the fact that we find everywhere below this oldest 
set of fossiliferous beds, other stratified rocks in 
which no trace of organized beings can be found. 
2 See, below, Sect. 21. 
3 See, below, Sect. 16. 
4 See, below, Sect. 15. 
6 See, below, Sect. 17. 
6 See, below, Sect. 6. Chap. I. 
DIVERSIFIED TYPES FOUND EVERYWHERE. 
15 
fauna and every flora upon the surface of the globe. How great the diversity of 
animals and plants living together in the same region may be, can be ascertained by 
the perusal of special works upon the Zoology and Botany of different countries, or 
from special treatises upon the geographical distribution of animals and plants.1 I 
need, therefore, not enter into further details upon this subject, especially since it is 
discussed more fully below.2 
It might, perhaps, be urged, that animals living together in exceptional conditions, 
and exhibiting structural peculiarities apparently resulting from these conditions, such 
as the blind fish,3 the blind crawfish, and the blind insects of the Mammoth Cave 
in Kentucky, furnish uncontrovertible evidence of the immediate influence of those 
exceptional conditions upon the organs of vision. If this, however, were the case, 
how does it happen that that remarkable fish, the Amblyopsis spelceus, has only such 
remote affinities to other fishes ? Or were, perhaps, the sum of influences at work to 
make that fish blind, capable also of devising such a combination of structural charac- 
ters as that fish has in common with all other fishes, with those peculiarities which 
at the same time distinguish it? Does not, rather, the existence of a rudimentary 
eye discovered by Dr. J. Wyman in the blind fish show, that these animals, like all 
others, were created with all their peculiarities by the fiat of the Almighty, and this 
rudiment of eyes left them as a remembrance of the general plan of structure of 
the great type to which they belong? Or will, perhaps, some one of those natural- 
ists who know so much better than the physicists what physical forces may produce, 
and that they may produce, and have produced every living being known, explain 
also to us why subterraneous caves in America produce blind fishes, blind Crustacea, 
and blind insects, while in Europe they produce nearly blind reptiles? If there is 
no thought in the case, why is it, then, that this very reptile, the Proteus anguinus, 
forms, with a number of other reptiles living in North America and in Japan, one of 
1 Schmarda, Die geographische Verbreitung der 
Thiere, 3 vols. 8vo. Wien, 1853. - Swainson, (W.,) 
A Treatise on the Geography and Classification of 
Animals, London, 1835,1 vol. 12mo. - Zimmermann, 
(E. A. G.,) Specimen Zoologi® geographic®, Quadru- 
pedum domicilia et migrationes sistens, Lugduni-Ba- 
tav., 1777, 1 vol. 4to. - Humboldt, Essai sur la geo- 
graphic des plantes, 4to., Paris, 1805; and Ansichten 
der Natur, 3d edit., 12mo., Stuttgardt and Tubin- 
gen, 1849. - Robert Brown, General Remarks on 
the Botany of Terra Australis, London, 1814.- 
Schouw, Grundziige einer allgemeinen Pflanzengeo- 
graphie, 1 vol. 8vo., with atlas in fol., Berlin, 1823. 
-Alph. de Candolle, Geographic botanique rai- 
sonnee, 2 vols. 8vo., Paris, 1855. References to 
special works may be found below, Sect. 9. 
2 See, below, Sect. 9. 
3 Wyman, (Jef.,) Description of a Blind Fish, 
from a Cave in Kentucky, Silliman's Jour., 1843, 
vol. 45, p. 94, and 1854, vol. 17, p. 258. - Tell- 
kampf, (Tn. G.,) Ueber den blinden Fisch der Mam- 
muthhbhle in Kentucky, in Muller's Archiv, 1844, 
p. 381. - Tellkampf, (Th. G.,) Beschreibung eini- 
ger neuer in der Mammuthhbhle aufgefundener Gat- 
tungen von Gliederthieren, Wiegman's Archiv, 1844, 
vol. I., p. 318. - Agassiz, (L.,) Observations on the 
Blind Fish of the Mammoth Cave, Silliman's Jour- 
nal, 1851, vol. 11, p. 127. 16 
ESSAY ON CLASSIFICATION. 
Part I. 
the most natural series known in the animal kingdom, every member of which 
exhibits a distinct grade 1 in the scale ? 
After we have freed ourselves from the mistaken impression that there may be 
some genetic connection between physical forces and organized beings, there remains 
a vast field of investigation to ascertain the true relations between both, to their full 
extent, and within their natural limits.2 A mere reference to the mode of breathing 
of different types of animals, and to their organs of locomotion, which are more 
particularly concerned in these relations, will remind every naturalist of how great 
importance in classification is the structure of these parts, and how much better they 
might be understood in this point of view, were the different structures of these 
organs more extensively studied in their direct reference to the world in which ani- 
mals live. If this had been done, we should no longer call by the same common 
name of legs and wings organs so different as the locomotive appendages of the 
insects and those of the birds? We should no longer call lungs the breathing 
cavity of snails, as well as the air pipes of mammalia, birds, and reptiles? A great 
reform is indeed needed in this part of our science, and no study can prepare us 
better for it than the investigation of the mutual dependence of the structure of 
animals, and the conditions in which they live. 
SECTION III. 
REPETITION OF IDENTICAL TYPES UNDER THE MOST DIVERSIFIED CIRCUMSTANCES. 
As much as the diversity of animals and plants living under identical physical 
conditions, shows the independence of organized beings from the medium in which 
they dwell, so far as their origin is concerned, so independent do they appear again 
from the same influences when we consider the fact that identical types occur every- 
where upon earth under the most diversified circumstances. If we sum up all these 
various influences and conditions of existence under the common appellation of 
cosmic influences, or of physical causes, or of climate in the widest sense of the 
word, and then look around us for the extreme differences in that respect upon the 
whole surface of the globe, we find still the most similar, nay identical types (and I 
allude here, under the expression of type, to the most diversified acceptations of the 
word) living normally under their action. There is no structural difference between 
the herrings of the Arctic, or those of the Temperate zone, or those of the Tropics, 
1 See, below, Sect. 12. 
2 See, below, Sect. 16. Chap. I. 
IDENTICAL TYPES FOUND EVERYWHERE. 
17 
or those of the Antarctic regions; there are not any more between the foxes and 
wolves of the most distant parts of the globe? Moreover, if there were any, and 
the specific differences existing between them were insisted upon, could any relation 
between these differences and the cosmic influences under which they live be pointed 
out, which would at the same time account for the independence of their structure 
in general ? Or, in other words, how could it be assumed that while these causes 
would produce specific differences, they would at the same time produce generic 
identity, family identity, ordinal identity, class identity, typical identity? Identity in 
every thing that is truly important, high, and complicated in the structure of ani- 
mals, produced by the most diversified influences, while at the same time these 
extreme physical differences, considered as the cause of the existence of these ani- 
mals, would produce diversity in secondary relations only! What logic! 
Does not all this show, on the contrary, that organized beings exhibit the most 
astonishing independence of the physical causes under which they live; an independ- 
ence so great that it can only be understood as the result of a power governing 
these physical causes as well as the existence of animals and plants, and bringing all 
into harmonious relations by adaptations which never can be considered as cause and 
effect ? 
When naturalists have investigated the influence of physical causes upon living 
beings, they have constantly overlooked the fact that the features which are thus 
modified are only of secondary importance in the life of animals and plants, and 
that neither the plan of their structure, nor the various complications of that struc- 
ture, are ever affected by such influences. What, indeed, are the parts of the body 
which are, in any way, affected by external influences? Chiefly those which are in 
immediate contact with the external world, such as the skin, and in the skin chiefly 
its outer layers, its color, the thickness of the fur, the color of the hair, the feathers, 
and the scales; then the size of the body and its weight, as far as it is dependent on 
the quality and quantity of the food; the thickness of the shell of Mollusks, when 
they live in waters or upon a soil containing more or less limestone, etc. The 
rapidity or slowness of the growth is also influenced in a measure by the course of 
the seasons, in different years; so is also the fecundity, the duration of life, etc. 
But all this has nothing to do with the essential characteristics of animals. 
A book has yet to be written upon the independence of organized beings of 
physical causes, as most of what is generally ascribed to the influence of physical 
agents upon organized beings ought to be considered as a connection established 
between them in the general plan of creation. 
1 Innumerable other examples might be quoted, 
which will readily present themselves to professional 
naturalists; those mentioned above may suffice for 
my argument. 18 
ESSAY ON CLASSIFICATION. 
Part L 
SECTION IV. 
UNITY OF PLAN IN OTHERWISE HIGHLY DIVERSIFIED TYPES. 
Nothing is more striking throughout the animal and vegetable kingdoms than the 
unity of plan in the structure of the most diversified types. From pole to pole, in 
every longitude, mammalia, birds, reptiles, and fishes, exhibit one and the same plan 
of structure,1 involving abstract conceptions of the highest order, far transcending the 
broadest generalizations of man, for it is only after the most laborious investigations 
man has arrived at an imperfect understanding of this plan. Other plans, equally 
wonderful, may be traced in Articulata, in Mollusks, in Radiata,2 and in the various 
types of plants,3 and yet this logical connection, these beautiful harmonies, this infi- 
nite diversity in unity are represented by some as the result of forces exhibiting no 
trace of intelligence, no power of thinking, no faculty of combination, no knowledge 
of time and space. If there is any thing which places man above all other beings 
in nature, it is precisely the circumstance that he possesses those noble attributes 
without which, in their most exalted excellence and perfection, not one of these 
1 With reference to this point, consult: Oken, 
(Lor.,) Ueber die Bedeutung der Schadel-Knochen, 
Frankfort, 1807, 4to. (pamphlet.)-Spix, (J. B.) 
Cephalogenesis, sive capitis ossei structura, formatio 
et significatio, Monachii, 1815, fol. - Geoffroy St. 
Hilaire, (Et.,) Philosophic anatomique, Paris, 
1818-1823, 2 vols. 8vo., and several papers in the 
Annal. des sc. nat., Annal. and Mem. du Museum, 
etc. - Carus, (C. G.,) Von den Ur-Theilen des 
Knochen- und Scbalengeriistes, Leipzig, 1828, fol.- 
Owen, (R.) On the Archetype and Homologies of 
the Vertebrate Skeleton, London, 1848, 8vo. 
2 Oken, (Lor.,) Lehrbucb der Naturphilosophie, 
Jena, 1809-11, 3 vols. 8vo.; Engl. Elements of 
Physio-philosophy, Ray Society, London, 1847, 8vo. 
- Cuvier, (G.,) Sur un nouveau rapprochement a 
etablir entre les classes qui composent le Regne Ani- 
mal, Annales du Museum, vol. xix., 1812. - Savi- 
gny, (J. C.,) Memoires sur les animaux sans verte- 
bres, Paris, 1816, 8vo. - Baer, (C. E. v.,) Ueber 
Entwickelungsgeschichte der Thiere, Konigsberg, 
1828, 4to.-Leukardt, (R.,) Ueber die Morphologic 
und die Verwandtschafts verbal tnisse der wirbellosen 
Thiere, Braunschweig, 1848, 8vo. - Agassiz, (L.,) 
Twelve Lectures on Comparative Embryology, Bos- 
ton, 1849, 8vo.-On Animal Morphology, Proc. Amer. 
Assoc, for the Adv. of Science, Boston, 1850, 8vo., p. 
411. I would call particular attention to this paper, 
which has immediate reference to the subject of this 
chapter. - Carus, (V.,) System der thierischen Mor- 
phologic, Leipzig, 1853, 1 vol. 8vo. 
8 Gotiie, (J. W.,) Zur Naturwissenhaft iiber- 
haupt, besonders zur Morphologic, Stuttgardt, 1817- 
24, 2 vols. 8vo.; French, Oeuvres d'histoire natu- 
relie, comprenant divers memoires d'Anatomie com- 
paree, de Botanique et de Geologic, traduits et an- 
notes par Ch. Fr. Martins, Paris, 1837, 8vo.; atlas 
in fol. - DeCandolle, (A. P.,) Organographie 
vegetale, Paris, 1827, 2 vols. 8vo. - Braun, (Al.,) 
Vergleichende Untersuchung liber die Ordnung der 
Scbuppen an den Tannenzapfen, als Einleitung zur 
Untersuchung der Blattstellung iiberhaupt, Act. Nov. 
Ac. Nat. Curios., vol. xv., 1829. - Das Individuum 
der Pflanze, Akad. d. Wise., Berlin, 1853, 4to. Chap. I. 
HOMOLOGIES IN DISCONNECTED ANIMALS. 
19 
general traits of relationship so characteristic of the great types of the animal and 
vegetable kingdoms, can be understood, or even perceived. How, then, could these 
relations have been devised without similar powers? If all these relations are almost 
beyond the reach of the mental powers of man, and if man himself is part and 
parcel of the whole system, how could this system have been called into existence 
if there does not exist One Supreme Intelligence, as the Author of all things? 
SECTION V. 
CORRESPONDENCE IN THE DETAILS OF STRUCTURE IN ANIMALS OTHERWISE ENTIRELY 
DISCONNECTED. 
During the first decade of this century, naturalists began to study relations among 
animals which had escaped almost entirely the attention of earlier observers. Though 
Aristotle knew already that the scales of fishes correspond to the feathers of birds,1 
it is but recently that anatomists have discovered the close correspondence which 
exists between all the parts of all animals belonging to the same type, however dif- 
ferent they may appear at first sight. Not only is the wing of the bird identical in 
its structure with the arm of man, or the fore leg of a quadruped, it agrees quite as 
closely with the fin of the whale, or the pectoral fin of the fish, and all these 
together correspond in the same manner with their hind extremities. Quite as strik- 
ing a coincidence is observed between the solid skull-box, the immovable bones 
of the face and the lower jaw of man and the other mammalia, and the structure of 
the bony frame of the head of birds, turtles, lizards, snakes, frogs, and fishes. But 
this correspondence is not limited to the skeleton; every other system of organs 
exhibits in these animals the same relations, the same identity in plan and structure, 
whatever be the differences in the form of the parts, in their number, and even in 
their functions. Such an agreement in the structure of animals is called their 
homology, and is more or less close in proportion as the animals in which it is 
traced are more or less nearly related. 
The same agreement exists between the different systems and their parts in Artic- 
ulata, in Mollusks, and in Radiata, only that their structure is built up upon respec- 
tively different plans, though in these three types the homologies have not yet been 
traced to the same extent as among Vertebrata. There is therefore still a wide 
1 Aristoteles, Historia Animalium, Lib. I., Chap. 
1, Sect. 4. o tv OQVtdt nttQov, tovto tv i^Ovi 
tou Itmg. - Consult also the authors referred to in 
Sect. 4, notes 1 and 2, and the many other works, 
pamphlets, and papers, quoted by them, which are too 
numerous to be mentioned here. 20 
ESSAY ON CLASSIFICATION. 
Part I. 
field open for investigations in this most attractive branch of Zoology. So much, 
however, is already plain from what has been done in this department of our science, 
that the identity of structure among animals does not extend to all the four branches 
of the animal kingdom; that, on the contrary, every great type is constructed upon 
a distinct plan, so peculiar, indeed, that homologies cannot be extended from one 
type to the other, but are strictly limited within each of them. The more remote 
resemblance which may be traced between representatives of different types, is 
founded upon analogy,1 and not upon affinity. While, for instance, the head of 
fishes exhibits the most striking homology with that of reptiles, birds, and mammalia, 
as a whole, as well as in all its parts, that of Articulata is only analogous to it and 
to its part. What is commonly called head in Insects is not a head like that of 
Vertebrata; it has not a distinct cavity for the brain, separated from that which 
communicates below the neck with the chest and abdomen; its solid envelope does 
not consist of parts of an internal skeleton, surrounded by flesh, but is formed of 
external rings, like those of the body, soldered together; it contains but one cavity, 
which includes the cephalic ganglion, as well as the organs of the mouth, and all the 
muscles of the head. The same may be said of the chest, the legs and wings, the 
abdomen, and all the parts they contain. The cephalic ganglion is not homologous 
to the brain, nor are the organs of senses homologous to those of Vertebrata, even 
though they perform the same functions. The alimentary canal is formed in a very 
different way in the embryos of the two types, as are also their respiratory organs, 
and it is as unnatural to identify them, as it would be still to consider gills and 
lungs as homologous among Vertebrata now embryology has taught us that in differ- 
ent stages of growth these two kinds of respiratory organs exist in all Vertebrata in 
very different organic connections one from the other. 
What is true of the branch of Articulata when compared to that of Vertebrata, 
is equally true of the Mollusks and Radiata when compared with one another or 
with the two other types, as might easily be shown by a fuller illustration of the 
correspondence of their structure, within these limits. This inequality in the fun- 
damental character of the structure of the four branches of the animal kingdom 
points to the necessity of a radical reform in the nomenclature of comparative 
anatomy.2 Some naturalists, however, have already extended such comparisons 
respecting the structure of animals beyond the limits pointed out by nature, when 
they have attempted to show that all structures may be reduced to one norm, and 
1 See Swainson, (W.,) On the Geography and 
Classification of Animals, London, 1835, 12mo., p. 
129, where this point is ably discussed. 
2 See Agassiz, (L.,) On the Structure and IIo- 
mologies of Radiated Animals, with Reference to 
the Systematic Position of the Hydroid Polypi, 
Proc, of the Amer. Assoc, for the Adv. of Science 
for 1849, Boston, 1850, 1 vol. 8vo. p. 389. Chap. I. 
DEGREES AND KINDS OF RELATIONSHIP. 
21 
when they have maintained, for instance, that every bone existing in any Vertebrate 
must have its counterpart in every other species of that type. To assume such a 
uniformity among animals, would amount to denying to the Creator even as much 
freedom in expressing his thoughts as man enjoys. 
If it be true, as pointed out above, that all animals are constructed upon four 
different plans of structure, in such a manner that all the different kinds of animals 
are only different expressions of these fundamental formulae, we may well compare 
the whole animal kingdom to a work illustrating four great ideas, between which 
there is no other connecting link than the unity exhibited in the eggs in which their 
most diversified manifestations are first embodied in an embryonic form, to undergo 
a series of transformations, and appear in the end in that wonderful variety of inde- 
pendent living beings which inhabit our globe, or have inhabited it from the earliest 
period of the existence of life upon its surface. 
The most surprising feature of the animal kingdom seems, however, to me to 
rest neither in its diversity, nor in the various degrees of complication of its struc- 
ture, nor in the close affinity of some of its representatives, while others are so 
different, nor in the manifold relations of all of them to one another and the sur- 
rounding world, but in the circumstance that beings endowed with such different and 
such unequal gifts should nevertheless constitute an harmonious whole, intelligibly 
connected in all its parts. 
SECTION VI. 
VARIOUS DEGREES AND DIFFERENT KINDS OF RELATIONSHIP AMONG ANIMALS. 
The degrees of relationship existing between different animals are most diversified. 
They are not only akin as representatives of the same species, bearing as such the 
closest resemblance to one another; different species may also be related as members 
of the same genus, the representatives of different genera may belong to the same 
family, and the same order may contain different families, the same class different 
orders, and the same type several classes. The existence of different degrees of 
affinity between animals and plants which have not the remotest genealogical connec- 
tion, which live in the most distant parts of the world, which have existed in periods 
long gone by in the history of our earth, is a fact beyond dispute, at least, within 
certain limits, no longer controverted by well informed observers. Upon what can 
this be founded ? Is it that the retentive capacity of the memory of the physical 
forces at work upon this globe is such, that after bringing forth a type according to 
one pattern, in the infancy of this earth, that pattern was adhered to under conditions, 22 
ESSAY ON CLASSIFICATION. 
Part I. 
no matter how diversified, to reproduce, at another period, something similar, and so 
on, through all ages, until at the period of the establishment of the present state of 
things, all the infinitude of new animals and new plants which now crowd its surface, 
should be cast in these four moulds, in such a manner as to exhibit, notwithstanding 
their complicated relations to the surrounding world, all those more deeply seated 
general relations, which establish among them the different degrees of affinity we 
may trace so readily in all the representatives of the same type ? Does all this 
really look more like the working of blind forces than like the creation of a reflec- 
tive mind establishing deliberately all the categories of existence we recognize in 
nature, and combining them in that wonderful harmony which unites all things into 
such a perfect system, that even to read it, as it is established, or even with all the 
imperfections of a translation, should be considered as the highest achievement of 
the maturest genius ? 
Nothing seems to me to prove more directly and more fully the action of a 
reflective mind, to indicate more plainly a deliberate consideration of the subject, 
than the different categories upon which species, genera, families, orders, classes, and 
branches are founded in nature, and manifested in material reality in a succession of 
individuals, the life of which is limited in its duration to comparatively very short 
periods. The great wonder in these relations consists in the fugitive character of the 
bearers of this complicated harmony. For while species persist during long periods, 
the individuals which represent them are ever changing, one set dying after the 
other, in quick succession. Genera, it is true, may extend over longer periods; fami- 
lies, orders, and classes may even have existed during all periods during which 
animals have existed at all; but whatever may have been the duration of their 
existence, at all times these different divisions have stood in the same relation to 
one another and to their respective branches, and have always been represented 
upon our globe in the same manner, by a succession ' of ever renewed and short-lived 
individuals. 
As, however, the second chapter of this work is entirely devoted to the consider- 
ation of the different kinds and the different degrees of affinity existing among 
animals, I will not enter here into any details upon this subject, but simply recall 
the fact that, in the course of time, investigators have agreed more and more with 
one another in their estimates of these relations, and built up systems more and 
more conformable to one another. This result, which is fully exemplified by the 
history of our science,1 is in itself sufficient to show that there is a system in nature 
1 Spix, (J.,) Gcschichte und Beurtheilung alter 
Systeme in der Zoologie, Nurnberg, 1811, 1 vol. 8vo. 
- Cuviek, (G.,) Ilistoire des progres des sciences 
naturelies, Paris, 1826, 4 vols. 8vo. - Ilistoire des 
sciences naturelles, etc., Paris, 1841, 5 vols. 8vo. 
- DeBlainville, (H.,) Ilistoire des sciences de Chap. I. 
EARLIEST TYPES OF ANIMALS. 
23 
to which the different systems of authors are successive approximations, more and 
more closely agreeing with it, in proportion as the human mind has understood 
nature better. This growing coincidence between our systems and that of nature 
shows further the identity of the operations of the human and the Divine intellect; 
especially when it is remembered to what an extraordinary degree many a priori 
conceptions, relating to nature, have in the end proved to agree with the reality, 
in spite of every objection at first offered by empiric observers. 
SECTION VII. 
SIMULTANEOUS EXISTENCE IN THE EARLIEST GEOLOGICAL PERIODS, OF ALL THE GREAT 
TYPES OF ANIMALS. 
It was formerly believed by geologists and palaeontologists that the lowest animals 
first made their appearance upon this globe, and that they were followed by higher 
and higher types, until man crowned the series. Every geological museum, repre- 
senting at all the present state of our knowledge, may now furnish the evidence 
that this is not the case. On the contrary, representatives of numerous families 
belonging to all the four great branches of the animal kingdom, are well known to 
have existed simultaneously in the oldest geological formations.1 Nevertheless, I well 
remember when I used to hear the great geologists of the time assert, that the 
Corals were the first inhabitants of our globe, that Mollusks and Articulata followed 
in order, and that Vertebrates did not appear until long after these. What an 
extraordinary change the last thirty years have brought about in our knowledge, and 
the doctrines generally adopted respecting the existence of animals and plants in past 
ages! However much naturalists may still differ in their views regarding the origin, 
the gradation, and the affinities of animals, they now all know that neither Radiata, 
nor Mollusks, nor Articulata, have any priority one over the other, as to the time 
1'organisation et de leurs progres, Paris, 1847, 3 vols. 
8vo. - Pouchet, (F. A.,) Histoire des sciences na- 
turelles au moyen age, Paris, 1853, 1 vol. 8vo. 
Compare, also, Chap. II., below. 
1 Murchison, (R. I.,) The Silurian System, Lon- 
don, 1839, 1 vol. 4to. - Murchison, (Sir R. I.,) 
Siluria. The History of the Oldest Known Rocks 
containing Fossils, London, 1854, 1 vol. 8vo. - Mur- 
chison, (R. I.,) de Verneuil, (Ed.,) and Kai- 
serling, (Count Alex, von,) The Geology of 
Russia in Europe, and the Ural Mountains, London, 
1845, 2 vols. 4to. - Hall, (James,) Palaeontology 
of New York, Albany, 1847-52, 2 vols. 4to. - Bar- 
rande, (J.,) Systeme sihirien du centre de la Bo- 
heme, Prague and Paris, 1852, 2 vols. 4to. - Sedg- 
wick, (A.,) and McKoy, (Fr.,) British Palaeozoic 
Rocks and Fossils, London, 1851, 4to. 2 fasc.; not 
yet complete. 24 
ESSAY ON CLASSIFICATION. 
Part I. 
of their first appearance upon earth; and though some still maintain that Vertebrata 
originated somewhat later, it is universally conceded that they were already in exist- 
ence toward the end of the first great epoch in the history of our globe. I think 
it would not be difficult to show upon physiological grounds that their presence upon 
earth dates from as early a period as any of the three other great types of the 
animal kingdom, since fishes exist wherever Radiata, Mollusks, and Articulata are 
found together, and the plan of structure of these four great types constitutes a 
system intimately connected in its very essence. Moreover, for the last twenty 
years, every extensive investigation among the oldest fossiliferous rocks has carried 
the origin of Vertebrata step by step further back, so that whatever may be the 
final solution of this vexed question, so much is already established by innumerable 
facts, that the idea of a gradual succession of Radiata, Mollusks, Articulata, and Ver- 
tebrata, is for ever out of the question. It is proved beyond doubt, that Radiata, 
Mollusca, and Articulata are everywhere found together in the oldest geological for- 
mations, and that very early Vertebrata are associated with them, to continue 
together through all geological ages to the present time. This shows that even in 
those early days of the existence of our globe, when its surface did not yet present 
those diversified features which it has exhibited in later periods, and which it exhibits 
in still greater variety now, animals belonging to all the great types now represented 
upon earth, were simultaneously called into existence. It shows, further, that unless 
the physical elements then at work could have devised such plans, and impressed 
them upon the material world as the pattern upon which Nature was to build for 
ever afterwards, no such general relations as exist among all animals, of all geo- 
logical periods, as well as among those now living, could ever have existed. 
This is not all: every class among Radiata, Mollusks, and Articulata, is known 
to have been represented in those earliest days, with the exception of the Acalephs1 
and Insects only. It is, therefore, not only the plan of the four great types which 
must have been adopted then, the manner in which these plans were to be executed, 
the systems of form under which these structures were to be clothed, even the ulti- 
mate details of structure which in different genera bear definite relations to those of 
other genera; the inode of differentiation of species, and the nature of their rela- 
tions to the surrounding media, must likewise have been determined, as the character 
of the classes is as well defined as that of the four great branches of the animal 
kingdom, or that of the families, the genera, and the species. Again, the first rep- 
resentatives of each class stand in definite relations to their successors in later 
1 Acalephs have been found in the Jurassic Lime- 
stone of Solenhofen ; their absence in other forma- 
tions may be owing simply to the extraordinary 
softness of their body. Insects are known as early 
as the Carboniferous Formation, and may have ex- 
isted before. Chap. I. 
EARLIEST TYPES OF ANIMALS. 
25 
periods, and as their order of apparition corresponds to the various degrees of com- 
plication in their structure, and forms natural series closely linked together, this 
natural gradation must have been contemplated from the very beginning. There 
can be the less doubt upon this point, as man, who comes last, closes in his own 
cycle a series, the gradation of which points from the very beginning to him as its 
last term. I think it can be shown by anatomical evidence that man is not onlv 
the last and highest among the living beings, for the present period, but that he is 
the last term of a series beyond which there is no material progress possible upon 
the plan upon which the whole animal kingdom is constructed, and that the only 
improvement we may look to upon earth, for the future, must consist in the develop- 
ment of man's intellectual and moral faculties.1 
The question has been raised of late how far the oldest fossils known may truly 
be the remains of the first inhabitants of our globe. No doubt extensive tracts of 
fossiliferous rocks have been intensely altered by plutonic agencies, and their organic 
contents so entirely destroyed, and the rocks themselves so deeply metamorphosed, 
that they resemble now more closely eruptive rocks even than stratified deposits. 
Such changes have taken place again and again up to comparatively recent periods, 
and upon a very large scale. Yet there are entire continents, North America, for 
instance, in which the palaeozoic rocks have undergone little, if any, alteration, and 
where the remains of the earliest representatives of the animal and vegetable king- 
doms are as well preserved as in later formations. In such deposits the evidence is 
satisfactory that a variety of animals belonging to different classes of the great 
branches of the animal kingdom have existed simultaneously from the beginning; so 
that the assumption of a successive introduction of these types upon earth is flatly 
contradicted by well established and well known facts.2 Moreover, the remains found 
in the oldest deposits, are everywhere closely allied to one another. In Russia, in 
Sweden, in Bohemia, and in various other parts of the world, where these oldest 
formations have been altered upon a more or less extensive scale, as well as in 
North America, where they have undergone little or no change, they present the 
same general character, that close correspondence in their structure and in the 
combination of their families, which shows them to have belonged to contempora- 
neous faunae. It would, therefore, seem that even where metamorphic rocks prevail, 
the traces of the earliest inhabitants of this globe have not been entirely obliterated. 
1 Agassiz, (L.,) An Introduction to the Study 
of Natural History, New York, 1847, 8vo. p. 57. 
2 Agassiz, (L.,) The Primitive Diversity and 
Number of Animals in Geological Times, Amer. 
Journ. of Science and Arts, 2d ser., vol. 17, 1854, 
p. 309. 26 
ESSAY ON CLASSIFICATION. 
Part I. 
SECTION VIII. 
THE GRADATION OF STRUCTURE AMONG ANIMALS. 
There is not only variety among animals and plants; they differ also as to their 
standing, their rank, their superiority or inferiority when compared to one another. 
But this rank is difficult to determine; for while, in some respects, all animals are 
equally perfect, as they perform completely the part assigned to them in the general 
economy of nature,1 in other respects there are such striking differences between 
them, that their very agreement in certain features points at their superiority or 
inferiority in regard to others. 
This being the case, the question first arises, Do all animals form one unbroken 
series from the lowest to the highest? Before the animal kingdom had been studied 
so closely as it has been of late, many able writers really believed that all animals 
formed but one simple continuous series, the gradation of which Bonnet has been 
particularly industrious in trying to ascertain.2 At a later period, Lamarck3 has 
endeavored to show further, that in the complication of their structure, all the 
classes of the animal kingdom represent only successive degrees, and he is so 
thoroughly convinced that in his systematic arrangement classes constitute one grad- 
ual series, that he actually calls the classes "degrees of organization." DeBlainville4 
has in the main followed in the steps of Lamarck, though he does not admit quite 
so simple a series, for he considers the Mollusks and Articulates as two diverging 
branches ascending from the Radiata, to converge again and unite in the Vertebrata. 
But since it is now known how the great branches of the animal kingdom may be 
circumscribed,5 notwithstanding a few doubtful points; since it is now known how 
1 Ehrenberg, (C. G.,) Das Naturreich des Men- 
schen, oder das Reich der willensfreien beseelten Na- 
turkorper, in 29 Classen ubersichtlich geordnet, Ber- 
lin, 1835, folio, (1 sheet). 
2 Bonnet, (Ch.,) Considerations sur les corps 
organises, Amsterdam, 1762, 2 vols. 8vo. - Contem- 
plations de la Nature, Amsterdam, 1764-65, 2 vols. 
8vo. - Palingenesie philosophique, Geneve, 1769, 2 
vols. 8vo. 
8 Lamarck, (J. B. de,) Philosophic zoologique, 
Paris, 1809, 2 vols. 8vo. 
4 Blainville, (II. D. de,) De 1'Organisation des 
Animaux, Paris, 1822, 1 vol. 8vo. 
5 Blumenbach, (J. Fr.,) Handbuch der verglei- 
chenden Anatomic, Gottingen, 1824, 1 vol. 8vo.; 
Engl, by W. Lawrence, London, 1827, 1 vol. 8vo. 
- Cuvier, (G.,) Lemons d'Anatomie comparee, rec. 
et publ. par MM. Dumeril et Duvemoy, Paris, 
1800-1805, 5 vols. 8vo.; 2de edit., rev. par MM. 
F. G. Cuvier et Laurillard, Paris, 1836-39, 10 vols. 
8vo. - Cuvier, (G.,) Le Regne animal distribud 
d'apres son organisation, Paris, 1817, 4 vols. 8vo. ' Chap. I. 
GRADATION OF STRUCTURE AMONG ANIMALS. 
27 
most classes should be characterized, and what is their respective standing; since 
every day brings dissenting views, respecting the details of classification, nearer 
together, the supposition that all animals constitute one continuous gradated series, 
can be shown to be contrary to nature. Yet the greatest difficulty in this inquiry, 
is to weigh rightly the respective standing of the four great branches of the whole 
animal kingdom; for, however plain the inferiority of the Radiata may seem, when 
compared with the bulk of the Mollusks or Articulata, or still more evident when 
contrasted with the Vertebrata, it must not be forgotten, that the structure of most 
Echinoderms is far more complicated than that of any Bryozoon or Ascidian of the 
type of Mollusks, or that of any Helminth, of the type of Articulata, and, perhaps, 
even superior to that of the Amphioxus among Vertebrata. These facts are so well 
ascertained, that an absolute superiority or inferiority of one type over the other 
must be unconditionally denied. As to a relative superiority or inferiority however, 
determined by the bulk of evidence, though it must be conceded that the Vertebrata 
rank above the three other types, the question of the relative standing of Mollusks 
and Articulata seems rather to rest upon a difference in the tendency of their whole 
organization, than upon a real gradation in their structure; concentration being the 
prominent trait of the structure of Mollusks, while the expression 'outward display' 
would more naturally indicate that of Articulata, and so it might seem as if Mollusks 
and Articulata were standing on nearly a level with one another, and as much 
2de edit. 1829-30, 5 vols. 8vo.; 3e edit, illustree 
1836 et suiv; Engl. Trans, by Griffith, London, 
1824, 9 vols. 8vo. - Meckel, (J. F.,) System der 
vergleichenden Anatomie, Halle, 1821-31, 6 vols. 
8vo.; French Transl., Paris, 1829-38, 10 vols. 8vo. 
- Treviranus, (G. R.,) Biologie, oder Philosophic 
der lebenden Natur, Gottingen, 1802-16, 6 vols. 8vo. 
- Die Erscheinungen und Gesetze des organischen 
Lebens, Bremen, 1831-37, 5 vols. 8vo. - Delle 
Chiaje, Istituzioni d'Anatomia e Fisiologia compa- 
rata, Napoli, 1832, 8vo. - Carus, (C. G.,) Lehrbuch 
der vergleichenden Anatomie, Leipzic, 1834, 2 vols., 
4to., fig. 2d edit.; Grundsatze der vergleichenden Ana- 
tomie, Dresden, 1828, 8vo.; Engl, by R. J. Gore, 
Bath, 1827, 2 vols. 8vo. Atlas. - Carus, (C. G.,) and 
Otto, (A. W.) Erlauterungstafeln zur vergleichen- 
den Anatomie, Leipzic, 1826-40, fol. - Wagner, 
(R.,) Lehrbuch der vergleichenden Anatomie, Leipzic, 
1834-35, 2 vol. 8vo.; Engl, by A. Tulk, London, 
1844, 1 vol. 8vo.; 2d edit. Lehrbuch der Zootomie, 
Leipzic, 1813-44, 1 vol. 8vo., 2d vol. by Frey and 
Leuckardt ; leones anatomicae, Leipzig, 1841, fol. 
- Grant, (R. E.) Outlines of Comparative Anat- 
omy, London, 1835, 1 vol. fol. - Jones, (Rymer,) 
A General Outline of the Animal Kingdom, London, 
1838-39, 1 vol. 8vo. fig.; 2d edit. 1854. - Todd, (R. 
B.,) Cyclopedia of Anatomy and Physiology, London, 
1835-52, 4 vol. 8vo. fig.-Agassiz, (L.,) and Gould, 
(A. A.,) Principles of Zoology, Boston, 1 vol. 8vo., 
2d edit. 1851. - Owen, (R.,) Lectures on the Inver- 
tebrate Animals, London, 1843, 1 vol. fig.; 2d edit. 
1855. - Lectures on the Comparative Anatomy of 
the Vertebrate Animals, Fishes, London, 1846, 1 vol. 
8vo. fig. - Siebold, (C. Th. v.,) und Stannius, 
(Herm.,) Lehrbuch der vergleichenden Anatomie, 
Berlin, 1845-46, 2 vol. 8vo.; 2d edit. 1855; Engl. 
Trans, by J. Burnett, Boston, 1854. - Berg- 
mann, (C.,) und Leuckardt, (R.,) Vergleichende 
Anatomie und Physiologic, Stuttgardt, 1852, 1 vol. 
8vo. fig. 28 
ESSAY ON CLASSIFICATION. 
Part I. 
above Radiata, as both stand below Vertebrata, but constructed upon plans expressing 
different tendencies. To appreciate more precisely these most general relations 
among the great types of the animal kingdom, will require deeper investigations into 
the character of their plan of structure than have been made thus far.1 Let, how- 
ever, the respective standing of these great divisions be what it may; let them differ 
only in tendency, or in plan of structure, or in the height to which they rise, 
admitting their base to be on one level or nearly so, so much is certain, that in 
each type there are representatives exhibiting a highly complicated structure and 
others which appear very simple. Now, the very fact that such extremes may be 
traced, within the natural boundaries of each type, shows that in whatever manner 
these great types are supposed to follow one another in a single series, the highest 
representative of the preceding type must join on to the lowest representative of 
the following, thus bringing necessarily together the most heterogeneous forms.2 It 
must be further evident, that in proportion as the internal arrangement of each great 
type will be more perfected, the greater is likely to appear the difference at the two 
ends of the series which are ultimately to be brought into connection with those of 
other series, in any attempt to establish a single series for all animals. 
I doubt whether there is a naturalist now living who could object to an arrange- 
ment in which, to determine the respective standing of Radiata, Polyps would be 
placed lowest, Acalephs next, and Echinoderms highest; a similar arrangement of 
Mollusks would bring Acephala lowest, Gasteropoda next, and Cephalopoda highest; 
Articulata would appear in the following order: Worms, Crustacea, and Insects, and 
Vertebrata, with the Fishes lowest, next Reptiles and Birds, and Mammalia highest. 
I have here purposely avoided every allusion to controverted points. Now if Mol- 
lusks were to follow Radiata in a simple series, Acephala should join on to the 
Echinoderms; if Articulata, Worms would be the connecting link. We should then 
have either Cephalopods or Insects, as the highest term of a series beginning with 
Radiata, followed by Mollusks or by Articulates. In the first case, Cephalopods 
would be followed by Worms; in the second, Insects by Acephala. Again, the con- 
nection with Vertebrata would be made either by Cephalopods, if Articulata were 
considered as lower than Mollusks, or by Insects, if Mollusks were placed below 
Articulata. Who does not see, therefore, that in proportion as our knowledge of the 
true affinities of animals is improving, we accumulate more and more convincing 
evidence against the idea that the animal kingdom constitutes one simple series? 
1 I regret to be unable to refer here to the con- 
tents of a course of lectures which I delivered upon 
this subject, in the Smithsonian Institution, in 1852. 
Compare, meanwhile, my paper, On the Differences 
between Progressive, Embryonic, and Prophetic 
Types, Proc. Am. Assoc, for 1849, p. 432. 
2 Agassiz, (L.,) Animal Morphology, Proc. Am. 
Assoc, for 1849, p. 415. Chap. I. 
GRADATION OF STRUCTURE AMONG ANIMALS. 
29 
The next question would then be: Does the animal kingdom constitute several, 
or any number of graduated series? In attempting to ascertain the value of the less 
comprehensive groups, when compared to one another, the difficulties seem to be 
gradually less and less. It is already possible to mark out with tolerable precision, 
the relative standing between the classes, though even here we do not yet perceive 
in all the types the same relations. Among Vertebrata, there can be little if any 
doubt, that the Fishes are lower than the Reptiles, these lower than Birds, and that 
Mammalia stand highest; it seems equally evident, that in the main, Insects and 
Crustacea are superior to Worms, Cephalopods to Gasteropods and Acephala and 
Echinoderms to Acalephs and Polypi. But there are genuine Insects, the superiority 
of which over many Crustacea, would be difficult to prove; there are Worms which 
in every respect appear superior to certain Crustacea; the structure of the highest 
Acephala seems more perfect than that of some Gasteropods, and that of the Halcyo- 
noid Polyps more perfect than that of many Hydroids. Classes do, therefore, not 
seem to be so limited in the range of their characters, as to justify in every type a 
complete serial arrangement among them. But when we come to the orders, it can 
hardly be doubted that the gradation of these natural divisions among themselves in 
each class, constitutes the very essence of this kind of groups. As a special para- 
graph is devoted to the consideration of the character of orders in my next chapter, 
I need not dwell longer upon this point here.1 It will be sufficient for me to 
remark now, that the difficulties geologists have met with, in their attempts to com- 
pare the rank of the different types of animals and plants with the order of their 
succession in different geological periods, has chiefly arisen from the circumstance, that 
they have expected to find a serial gradation, not only among the classes of the 
same type, where it is only incomplete, but even among the types themselves, 
between which such a gradation cannot be traced. Had they limited their compari- 
sons to the orders which are really founded upon gradation, the result would have 
been quite different; but to do this requires more familiarity with Comparative 
Anatomy, with Embryology and with Zoology proper, than can naturally be expected 
of those, the studies of which are chiefly devoted to the investigation of the struct- 
ure of our globe. 
To appreciate fully the importance of this question of the gradation of animals, 
and to comprehend the whole extent of the difficulties involved in it, a superficial 
acquaintance with the perplexing question of the order of succession of animals in 
past geological ages, is by no means sufficient; a complete familiarity with the many 
attempts which have been made to establish a correspondence between the two, and 
with all the crudities which have been published upon this subject, might dispel 
1 See Chap. II. 30 
ESSAY ON CLASSIFICATION. 
Part I. 
every hope to arrive at any satisfactory result upon this subject, did it not appear 
now, that the inquiry must be circumscribed within different limits, to be conducted 
upon its true ground. The results to which I have already arrived, since 1 have 
perceived the mistake under which investigators have been laboring thus far, in 
this respect, satisfy me that the point of view under which I have presented the 
subject here is the true one, and that in the end, the characteristic gradation 
exhibited by the orders of each class, will present the most striking correspondence 
with the character of the succession of the same groups in past ages, and afford 
another startling proof of the admirable order and gradation which have been estab- 
lished from the very beginning, and maintained through all times in the degrees of 
complication of the structure of animals. 
SECTION IX. 
RANGE OF GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 
The surface of the earth being partly formed by water and partly by land, and 
the organization of all living beings standing in close relation to the one or the other 
of these mediums, it is in the nature of things, that no single species, either of ani- 
mals or plants, should be uniformly distributed over the whole globe. Yet there 
are some types of the animal, as well as of the vegetable kingdom, which are equably 
distributed over the whole surface of the land, and others which are as widely scat- 
tered in the sea, while others are limited to some continent or some ocean, to some 
particular province, to some lake, nay, to some very limited spot of the earth's 
surface.1 
As far as the primary divisions of animals are concerned, and the nature of the 
medium to which they are adapted does not interfere, representatives of the four 
great branches of the animal kingdom are everywhere found together. Radiata, 
Mollusks, Articulata, and Vertebrata occur together in every part of the ocean, in 
the Arctics, as well as under the equator, and near the southern pole as far as man 
has penetrated; every bay, every inlet, every shoal is haunted by them. So univer- 
1 The human race affords an example of the wide 
distribution of a terrestrial type; the Herring and 
the Mackerel families have an equally wide distri- 
bution in the sea. The Mammalia of New Hol- 
land show how some families may be limited to one 
continent; the family of Labyrinthici of the Indian 
Ocean, how fishes may be circumscribed in the sea, 
and that of the Goniodonts of South America in 
the fresh waters. The Chaca of Lake Baikal is 
found nowhere else; this is equally true of the 
Blindfish (Amblyopsis) of the Mammoth Cave, and 
of the Proteus of the caverns of Carinthia. Chap. I. 
GEOGRAPHICAL RANGE OF ANIMALS. 
31 
sal is this association, not only at present but in all past geological ages, that I 
consider it as a sufficient reason to expect, that fishes will be found in those few 
fossiliferous beds of the Silurian System, in which thus far they have not yet been 
found.1 Upon land, we find equally everywhere Vertebrata, Articulata, and Mollusks, 
but no Radiata, this whole branch being limited to the waters; but as far as terres- 
trial animals extend, we find representatives of the other three branches associated, 
as we find them all four in the sea. Classes have already a more limited range of 
distribution. Among Radiata, the Polypi, Acalephs, and Echinoderms2 are not only 
all aquatic, they are all marine, with a single exception,3 the genus Hydra, which 
inhabits fresh waters. Among Mollusks,4 the Acephala are all aquatic, but partly 
marine and partly fluviatile, the Gasteropoda partly marine, partly fluviatile and 
partly terrestrial, while all Cephalopoda are marine. Among Articulata,5 the Worms 
are partly marine, partly fluviatile, and partly terrestrial, while many are internal 
1 See, above, Sect. 7. 
2 For the geographical distribution of Radiata, 
consult: Dana, (J. D.,) Zoophytes. United States 
Exploring Expedition, under the command of Ch. 
Wilkes, U. S. N., Philadelphia, 1846, 1 vol. 4to. 
Atlas fol. - Milne-Edwards et Haime, (Jul.,) 
Recherches sur les Polypiers, Ann. Sc. Nat. 3e ser. 
vol. 9-18, Paris, 1848-52, 8vo. - Eschscholtz, 
(Fr.,) System der Acalephen, Berlin, 1829, 4to. fig. 
- Lesson, (R. Pr.,) Histoire naturelie des Zoophy- 
tes, Acalephes, Paris, 1843, 1 vol. 8vo. fig. - Kolli- 
ker, (A.,) Die Schwimmpolypen und Siphonophoren 
von Messina, Leipzic, 1853, 1 vol. fol. fig. - Mul- 
ler, (J.,) und Troschel, (F. H.,) System der 
Asteriden, Braunschweig, 1842, 8vo. fig.- Agassiz, 
(L.,) Catalogue raisonne des families, des genres et 
des especes de la Classe des Echinodermes, Ann. des 
Sc. Nat. 3e ser. vol. 6-8, Paris, 1847, 8vo. 
8 I need hardly say in this connection that the 
so-called fresh-water Polyps, Alcyonella, Plumatella, 
etc., are Bryozoa, and not true Polyps. 
4 For the geographical distribution of Mollusks, 
consult: Lamarck, (J. B. de,) Histoire naturelie 
des Animaux sans vertebres, Paris, 1815-22, 7 vols. 
8vo.; 2de edit, augmentee de notes par MM. 
DesHayes and Milne-Edwards, Paris, 1835-43, 
10 vols. 8vo. - Ferussac, (J. B. L. de,) Histoire 
naturelle des Mollusques terrestres et fluviatiles. 
Paris, 1819 et suiv, 4to. fig. fol., continuee par Des- 
Hayes.- Ferussac, (J. B. L. de,) et Sander- 
Rang, (A.,) Histoire naturelie des Aplysiens, Paris, 
1828, 4to. fig. fol. - Ferussac, (J. B. L. de,) et 
d'Orbigny, (A.,) Monographic des Cephalopodes 
cryptodibranches, Paris, 1834-43, fol. - Martini, 
(F. H. W.,) und Chemnitz, (J. H.) Neues syste- 
matisches Conchylien-Kabinet, Nurnberg, 1769-95, 
11 vols. 4to. fig.; new edit, and continuation by 
Schubert and A. Wagner, completed by H. C. 
Kuster, Nurnberg, 11 vols. 4to. fig. - Kiener, (L. 
C.,) Species general et Iconographie des Coquilles 
vivantes, Paris, 1834, et suiv, 8vo. fig. - Reeve, 
(Lovell,) Conchologia Iconica; a Complete Repertory 
of Species of Shells, Pictorial and Descriptive, Lon- 
don, 1843, and foil., 4to. fig. - Pfeiffer, (L.,) Mon- 
ographia Heliceorum viventium, Leipzig, 1847-48, 
8vo.-Pfeiffer, (L.,) Monographia Pneumonopo- 
morum viventium, Cassel, 1852, 8vo., and all the 
special works on Conchology. 
5 The mode of distribution of free or parasitic 
Worms, in different parts of the world and in differ- 
ent animals, may be ascertained from: Grube, (A. 
Ed.,) Die Familien der Anneliden, Wiegman's Ar- 
chiv, 1850. I mention this paper in preference to 
any other work, as it is the only complete list of An- 
nulata; and though the localities are not given, the 
references may supply the deficiency. - Rudolphi, 
(K. A.,) Entozoorum sive Vermium intestinalium 
Historia naturalis, Amstelodami, 1808-10, 3 vols. 32 
ESSAY ON CLASSIFICATION. 
Part 1. 
parasites, living in the cavities or in the organs of other animals; the Crustacea are 
partly marine and partly fluviatile, a few are terrestrial; the Insects are mostly ter- 
restrial or rather aerial, yet some are marine, others fluviatile, and a large number ol 
those, which in their perfect state live in the air, are terrestrial or even aquatic 
during their earlier stages of growth. Among Vertebrata1 the Fishes are all aquatic, 
but partly marine and partly fluviatile; the Reptiles are either aquatic, or amphibious 
or terrestrial, and some of the latter are aquatic during the early part of their life; 
the Birds are all aerial, but some more terrestrial and others more aquatic; finally, 
the Mammalia though all aerial live partly in the sea, partly in fresh water, but 
mostly upon land. A more special review might show, that this localization in con- 
nection with the elements in which animals live, has a direct reference to peculiari- 
ties of structure of such importance, that a close consideration of the habitat of ani- 
mals within the limits of the classes, might in most cases lead to a very natural 
classification.2 But this is true only within the limits of the classes, and even here 
8vo. fig. - Entozoorum Synopsis, Berolini, 1819, 8vo. 
fig. - Gurlt, (E. F.,) Verzeichniss der Thiere, bei 
welchen Entozoen gefunden worden sind, Wiegman's 
Archiv, 1845, contin. by Creplin in the following No. 
- Dujardin, (Fel.,) Ilistoire naturelie des Hel- 
minthes ou Vers intestinaux, Paris, 1844, 1 vol. 8vo. 
- Diesing, (C. NI..) Historia Vermium, Vindob. 1850, 
2 vols. 8vo. That of Crustacea from Milne-Ed- 
wards, Ilistoire naturelie des Crustaces, Paris, 1834, 
3 vols. 8vo. fig. - Dana, (J. D.,) Crustacea. Uni- 
ted States Exploring Expedition, under the command 
of Ch. Wilkes, U. S. N., vol. xiv., Philadelphia, 1852, 
2 vols. 4to., atlas, fol. For the geographical distri- 
bution of Insects I must refer to the general works 
on Entomology, as it would require pages to enu- 
merate even the standard works relating to the dif- 
ferent orders of this class; but they are mentioned 
in: Percheron, (Ach. R.,) Bibliographic entomo- 
logique, Paris, 1837, 2 vols. 8vo. - Agassiz, (L.,) 
Bibliographia Zoologiae et Geologise; a general cata- 
logue of all books, tracts, and memoirs on Zoology 
and Geology, corrected, enlarged, and edited by 11. 
E.Strickland, London, 1848-54, 4 vols. 8vo. (Ray 
Society). 
1 For the geographical distribution of Fishes, 
consult: Cuvier, (G.,) and Valenciennes, (A.,) 
Ilistoire naturelie des Poissons, Paris, 1828-1849, 22 
vols. 8vo., fig. - Muller, (J.,) und Henle, (J.,) 
Systematische Beschreibung der Plagiostomen, Ber- 
lin, 1841, fol. fig. For that of Reptiles: Dumeril, 
(A. M. C.,) et Bibron, (G.,) Erpetologie generale, 
on Ilistoire naturelie complete des Reptiles, Paris, 
1834-1855, 9 vols. 8vo. fig. - Tschudi, (J. J.,) 
Classification der Batrachier, Neuchatel, 1838, 4to. 
Mem. Soc. Neuch. 2d. vol. - Fitzinger, (L. J.,) 
Systema Reptilium, Vindobonae, 1843, 8vo. For that 
of Birds: Gray, (G. R.,) The Genera of Birds, illus- 
trated with about 350 plates by I). W. Mitchell, Lon- 
don, 1844-1849, 3 vols. imp. 4to. - Bonaparte, 
(C. L.,) Conspectus generum Avium, Lugduni-Bata- 
vorum, 1850, and seq. 8vo. For that of Mammalia: 
Wagner, (A.,) Die geographische Verbreitung der 
Saugthiere, Verhandl. der Akad. der Wissensch. 
in Munchen, Vol. IV. - Pompper, (Herm.,) Die 
Saugthiere, Vogel und Amphibien, nach ihrer geo- 
graphischen Verbreitung tabellarish zusammenge- 
stellt, Leipzig, 1841, 4to. - See, also, the annual 
reports in Wiegman's Archiv, now edited by Tro- 
schell; the Catalogues of the British Museum, of 
the Jardin des Plantes, etc. 
2 Agassiz, (L.,) The Natural Relations between 
Animals and the Elements in which they live. 
Amer. Jour, of Sc. and Arts, 2d ser., vol. 9, 1850. 
8vo., p. 369. Chap. I. 
GEOGRAPHICAL RANGE OF ANIMALS. 
33 
not absolutely, as in some the orders only, or the families only are thus closely 
related to the elements; there are even natural groups, in which this connection is 
not manifested beyond the limits of the genera, and a few cases in which it is actually 
confined to the species. Yet, in every degree of these connections, we find that upon 
every spot of the globe, it extends simultaneously to the representatives of different 
classes and even of different branches of the animal and vegetable kingdoms; a circum- 
stance which shows that when called into existence, in such an association, these vari- 
ous animals and plants were respectively adapted with all the peculiarities of their 
kingdom, those of their class, those of their order, those of their genus, and those of 
their species, to the home assigned to them, and therefore, not produced by the nature 
of the place, or of the element, or any other physical condition. To maintain the 
contrary, would really amount to asserting that wherever a variety of organized 
beings live together, no matter how great their diversity, the physical agents prevail- 
ing there, must have in their combined action, the power of producing such a 
diversity of structures as exists in animals, notwithstanding the close connection in 
which these animals stand to them, or to work out an intimate relation to them- 
selves in beings, the essential characteristics of which, have no reference to their 
nature. In other words, in all these animals and plants, there is one side of their 
organization which has an immediate reference to the elements in which they live, 
and another which has no such connection, and yet it is precisely this part of the 
structure of animals and plants, which has no direct bearing upon the conditions in 
which they are placed in nature, which constitutes their essential, their typical 
character. This proves beyond the possibility of an objection, that the elements in 
which animals and plants live (and under this expression I mean to include all that 
is commonly called physical agents, physical causes, etc.,) cannot in any way be con- 
sidered as the cause of their existence. 
If the naturalists of past centuries have failed to improve their systems of Zoology 
by introducing considerations derived from the habitat of animals, it is chiefly because 
they have taken this habitat as the foundation of their primary divisions; but 
reduced to its proper limits, the study of the connection between the structure and 
the natural home of animals cannot fail to lead to interesting results, among which, 
the growing conviction that these relations are not produced by physical agents, 
but determined in the plan ordained from the beginning, will not be the least 
important. 
The unequal limitation of groups of a different value, upon the surface of the 
earth, produces the most diversified combinations possible, when we consider the 
mode of association of different families of animals and plants in different parts of 
the world. These combinations are so regulated that every natural province has a 
character of its own, as far as its animals and plants are concerned, and such natural 34 
ESSAY ON CLASSIFICATION. 
Part I. 
associations of organized beings extending over a wider or narrower area are called 
Faunce when the animals alone are considered, and Florce when the plants alone are 
regarded. Their natural limits are far from being yet ascertained satisfactorily 
everywhere. As the works of Schow and Schmarda may suffice to give an approxi- 
mate idea of their extent,1 I would refer to them for further details, and allude here 
only to the unequal extent of these different faunae, and to the necessity of limiting 
them in different ways, according to the point of view under which they are con- 
sidered, or rather show that, as different groups have a wider or more limited range, 
in investigating their associations, or the faunae, we must distinguish between zoologi- 
cal realms, zoological provinces, zoological counties, zoological fields, as it were; that 
is, between zoological areas of unequal value over the widest of which range the 
most extensive types, while in their smaller and smaller divisions, we find more and 
more limited types, sometimes overlapping one another, sometimes placed side by 
side, sometimes concentric to one another, but always and everywhere impressing a 
special character upon some part of a wider area, which is thus made to differ from 
that of any other part within its natural limits. 
These various combinations of smaller or wider areas, equally well defined in 
different types, has given rise to the conflicting views prevailing among naturalists 
respecting the natural limits of faunae; but with the progress of our knowledge 
these discrepancies cannot fail to disappear. In some respect, every island of the 
Pacific upon which distinct animals are found, may be considered as exhibiting a 
distinct fauna, yet several groups of these islands have a common character, which 
unites them into more comprehensive faunae, the Sandwich Islands for instance, com- 
pared to the Fejees or to New Zealand. What is true of disconnected islands or of 
isolated lakes is equally true of connected parts of the mainland and of the ocean. 
Since it is well known that many animals are limited to a very narrow range 
in their geographical distribution, it would be a highly interesting subject of inquiry 
to ascertain what are the narrowest limits within which animals of different types 
may be circumscribed, as this would furnish the first basis for a scientific consid- 
eration of the conditions under which animals may have been created. The time 
is passed when the mere indication of the continent whence an animal had been 
obtained, could satisfy our curiosity; and the naturalists who, having an opportunity 
of ascertaining closely the particular circumstances under which the animals they 
describe are placed in their natural home, are guilty of a gross disregard of the 
interest of science when they neglect to relate them. Our knowledge of the geo- 
graphical distribution of animals would be far more extensive and precise than it 
1 I would also refer to a sketch I have pub- 
lished of the Faun® in Nott's and Gliddon's 
Types of Mankind, Philadelphia, 1854, 4to., accom- 
panied with a map and illustrations. Chap. I. 
GEOGRAPHICAL RANGE OF ANIMALS. 
35 
is now, but for this neglect; every new fact relating to the geographical distribu- 
tion of well-known species is as important to science as the discovery of a new 
species. Could we only know the range of a single animal as accurately as 
Alphonse DeCandolle has lately determined that of many species of plants, we 
might begin a new era in Zoology. It is greatly to be regretted that in most 
works, containing the scientific results of explorations of distant countries, only new 
species are described, when the mere enumeration of those already known might have 
added invaluable information respecting their geographical distribution. The careless- 
ness with which some naturalists distinguish species merely because they are found 
in distant regions, without even attempting to secure specimens for comparison, is a 
perpetual source of erroneous conclusions in the study of the geographical distribu- 
tion of organized beings, not less detrimental to the progress of science than the 
readiness of others to consider as identical, animals and plants which may resemble 
each other closely, without paying the least regard to their distinct origin, and 
without even pointing out the differences they may perceive between specimens from 
different parts of the world. The perfect identity of animals and plants living in 
very remote parts of the globe has so often been ascertained, and it is also so 
well known how closely species may be allied and yet differ in all the essential 
relations which characterize species, that such loose investigations are no longer 
justifiable. 
This close resemblance of animals and plants in distant parts of the world is the 
most interesting subject of investigation with reference to the question of the unity 
of origin of animals, and to that of the influence of physical agents upon organized 
beings in general. It appears to me that as the facts point now distinctly to an 
independent origin of individuals of the same species in remote regions, or of 
closely allied species representing one another in distant parts of the world, one 
of the strongest arguments in favor of the supposition that physical agents may have 
had a controlling influence in changing the character of the organic world, is gone 
for ever. 
The narrowest limits within which certain Vertebrata may be circumscribed, is 
exemplified, among Mammalia, by some large and remarkable species: the Orang- 
Outangs upon the Sunda Islands, the Chimpanzee and the Gorilla along the west- 
ern coast of Africa, several distinct species of Rhinoceros about the Cape of Good 
Hope, and in Java and Sumatra, the Pinchaque and the common Tapir in South 
America, and the eastern Tapir in Sumatra, the East Indian and the African Ele- 
phant, the Bactrian Camel and the Dromedary, the Llamas, and the different kinds 
of wild Bulls, wild Goats, and wild Sheep, etc.; among birds by the African Ostrich, 
the two American Rheas, the Caso vary (Dromicejus) of New Holland, and the Emeu 
(Casuarius galeatus) of the Indian Archipelago, and still more by the different 36 
ESSAY ON CLASSIFICATION. 
Part I. 
species of doves confined to particular islands in the Pacific Ocean; among Reptiles, 
by the Proteus of the cave of Adelsberg in Carinthia, by the Gopher (Testudo Poly- 
phemus Auct.) of our Southern States; among fishes, by the Blind Fish (Amblyopsis 
spelams) of the Mammoth Cave. Examples of closely limited Articulata may not be 
so striking, yet the Blind Crawfish of the Mammoth Cave and the many parasites 
found only upon or within certain species of animals, are very remarkable in this 
respect. Among Mollusks, I would remark the many species of land shells, ascer- 
tained by Professor Adams to occur only in Jamaica,1 among the West India Islands, 
and the species discovered by the United States Exploring Expedition upon isolated 
islands of the Pacific, and described by Dr. Gould.2 Even among Radiata many 
species might be quoted, among Echinoderms as well as among Medusas and Polypi, 
which are only known from a few localities; but as long as these animals are not 
collected with the special view of ascertaining their geographical range, the indica- 
tions of travellers must be received with great caution, and any generalization 
respecting the extent of their natural area would be premature as long as the coun- 
tries they inhabit have not been more extensively explored. It is nevertheless true 
as established by ample evidence, that within definite limits all the animals occurring 
in different natural zoological provinces are specifically distinct. What remains to 
be ascertained more minutely is the precise range of each species, as well as the 
most natural limits of the different faunae. 
SECTION X. 
IDENTITY OF STRUCTURE OF WIDELY DISTRIBUTED TYPES. 
It is not only when considering the diversification of the animal kingdom within 
limited geographical areas, that we are called upon in our investigations to admire 
the unity of plan its most diversified types may exhibit; the identity of structure of 
these types is far more surprising, when we trace it over a wide range of country, 
and within entirely disconnected areas. Why the animals and plants of North 
America should present such a strong resemblance to those of Europe and Northern 
Asia, while those of Australia are so entirely different from those of Africa and South 
America under the same latitudes, is certainly a problem of great interest in connec- 
1 Adams, (C. B.,) Contributions to Conchology, 
New York, 1849-50, 8vo. A series of pamphlets, 
full of original information. 
2 Gould, (A. A.,) Mollusks, United States Ex- 
ploring Expedition, under the command of Ch. 
Wilkes, U. S. N., 1 vol. 4to. Philadelphia, 1854. Chap. I. 
STRUCTURE AND GEOGRAPHICAL DISTRIBUTION. 
37 
tion with the study of the influence of physical agents upon the character of animals 
and plants in different parts of the world. North America certainly does not resem- 
ble Europe and Northern Asia, more than parts of Australia resemble certain parts 
of Africa or of South America, and even if a greater difference should be conceded 
between the latter than between the former, these disparities are in no way com- 
mensurate with the difference or similarity of their organized beings, nor in any way 
rationally dependent one upon the other. Why should the identity of species pre- 
vailing in the Arctics not extend to the temperate zone, when many species of this 
zone, though different, are as difficult to distinguish, as it is difficult to prove the 
identity of certain arctic species, in the different continents converging to the north, 
and when besides, those of the two zones mingle to a great extent at their boun- 
daries? Why are the antarctic species not identical with those of the arctic regions? 
And why should a further increase of the average temperature introduce such com- 
pletely new types, when even in the Arctics, there are in different continents such 
strikingly peculiar types (the Rhytina for instance,) combined with those that are 
identical over the whole arctic area?1 
It may at first sight seem very natural that the arctic species should extend 
over the three northern continents converging towards the north pole, as there can 
be no insuperable barrier to the widest dissemination over this whole area for ani- 
mals living in a glacial ocean or upon parts of three continents which are almost 
bound together by ice. Yet the more we trace this identity in detail, the more 
surprising does it appear, as we find in the Arctics as well as everywhere else, repre- 
sentatives of different types living together. The arctic Mammalia belonging chiefly 
to the families of Whales, Seals, Bears, Weasels, Foxes, Ruminants and Rodents, 
have, as Mammalia, the same general structure as the Mammalia of any other part 
of the globe, and so have the arctic Birds, the arctic Fishes, the arctic Articulata, the 
arctic Mollusks, the arctic Radiata when compared to the representatives of the same 
types all over our globe. This identity extends to every degree of affinity among 
these animals and the plants which accompany them; their orders, their families, and 
their genera as far as they have representatives elsewhere, bear everywhere the 
same identical ordinal, family, or generic characters; the arctic foxes have the same 
1 I beg not to be misunderstood. I do not im- 
pute to all naturalists the idea of ascribing all the 
differences or all the similarities of the organic 
world to climatic influences; I wish only to remind 
them that even the truest picture of the correla- 
tions of climate and geographical distribution, does 
not yet touch the question of origin, which is the 
point under consideration. Too little attention has 
thus far been paid to the facts bearing upon the 
peculiarities of structure of animals in connection 
with the range of their distribution. Such investi- 
gations are only beginning to be made, as native 
investigators are studying comparatively the anatomy 
of animals of different continents. 38 
ESSAY ON CLASSIFICATION. 
Part I. 
dental formula, the same toes and claws, in fact, every generic peculiarity which 
characterizes foxes, whether they live in the Arctics, or in the temperate or tropical 
zone, in America, in Europe, in Africa, or in Asia. This is equally true of the seals 
or the whales; the same details of structure which characterize their genera in the 
Arctics reappear in the Antarctics, and the intervening space, as far as their natural 
distribution goes. This is equally true of the birds, the fishes, etc., etc. And let it 
not be supposed that it is only a general resemblance. By no means. The struc- 
tural identity extends to the most minute details in the most intimate structure of 
the teeth, of the hair, of the scales, in the furrows of the brain, in the ramification 
of the vessels, in the folds of the internal surface of the intestine, in the complica- 
tion of the glands, etc., etc., to peculiarities, indeed, which nobody but a professional 
naturalist, conversant with microscopic anatomy, would ever believe could present 
such precise and permanent characters. So complete, indeed, is this identity, that 
were any of these beings submitted to the investigation of a skilful anatomist, after 
having been mutilated to such an extent that none of its specific characters could 
be recognized, yet not only its class, or its order, or its family, but even its genus, 
could be identified as precisely as if it were perfectly well preserved in all its parts. 
Were the genera few which have a wide range upon the earth and in the ocean, 
this might be considered as an extraordinary case; but there is no class of animals 
and plants which does not contain many genera, more or less cosmopolite in their 
geographical distribution. The number of animals which have a wide distribution is 
even so great that, as far at least as genera are concerned, it may fairly be said, 
that the majority of them have an extensive geographical range. This amounts to 
the most complete evidence that, as far as any of these genera extends in its geo- 
graphical distribution, animals the structure of which is identical within this range of 
distribution, are entirely beyond the influence of physical agents, unless these agents 
have the power, notwithstanding their extreme diversity, within these very same 
geographical limits, to produce absolutely identical structures of the most diversified 
types. 
It must be remembered here, that there are genera of Vertebrata, of Articulata, 
of Mollusks, and of Radiata, which occupy the same identical and wide geographical 
distribution, and that while the structure of their respective representatives is identi- 
cal over the whole area, as Vertebrata, as Articulata, as Mollusks, as Radiata, they 
are at the same time built upon the most different plans. I hold this fact to be in 
itself a complete demonstration of the entire independence of physical agents of the 
structure of animals, and I may add that the vegetable kingdom presents a series of 
facts identical with these. This proves that all the higher relations among animals 
and plants are determined by other causes than mere physical influences. Chap. I. STRUCTURE AND GEOGRAPHICAL DISTRIBUTION. 
39 
While all the representatives of the same genus are identical in structure,1 the 
different species of one genus differ only in their size, in the proportions of their 
parts, in their ornamentation, in their relations to the surrounding elements, etc. 
The geographical range of these species varies so greatly, that it cannot afford in 
itself a criterion for the distinction of species. It appears further, that while some 
species which are scattered over very extensive areas, occupy disconnected parts of 
that area, other species closely allied to one another and which are generally desig- 
nated under the name of representative species, occupy respectively such disconnected 
sections of these areas. The question then arises, how these natural boundaries 
assigned to every species are established. It is now generally believed that each 
species had, in the beginning, some starting point, from which it has spread over 
the whole range of the area it now occupies, and that this starting point is still 
indicated by the prevalence or concentration of such species in some particular part 
of its natural area, which, on that account, is called its centre of distribution or 
centre of creation, while at its external limits the representatives of such species thin 
out, as it were, occurring more sparsely and sometimes in a reduced condition. 
It was a great progress in our science, when the more extensive and precise 
knowledge of the geographical distribution of organized beings forced upon its 
cultivators the conviction, that neither animals nor plants could have originated upon 
one and the same spot upon the surface of the earth, and hence have spread more 
and more widely until the whole globe became inhabited. It was really an immense 
progress which freed science from the fetters of an old prejudice; for now we have 
the facts of the case before us, it is really difficult to conceive how, by assuming 
such a gradual dissemination from one spot, the diversity which exists in every part 
of the globe could ever have seemed to be explained. But even to grant distinct 
centres of distribution for each species within their natural boundaries, is only to 
meet the facts half way, as there are innumerable relations between the animals and 
plants which we find associated everywhere, which must be considered as primitive, 
and cannot be the result of successive adaptation. And if this be so, it would 
follow that all animals and plants have occupied, from the beginning, those natural 
boundaries within which they stand to one another in such harmonious relations.2 
Pines have originated in forests, heaths in heathers, grasses in prairies, bees in hives, 
herrings in schools, buffaloes in herds, men in nations!3 I see a striking proof that 
this must have been the case in the circumstance, that representative species, which, 
1 See hereafter, Chap. II. Sect. 5. 
2 Agassiz, (L.,) Geographical Distribution of 
Animals, Christian Examiner, Boston, 1850, 8vo. 
(March). 
3 Agassiz, (L.,) The Diversity of Origin of the 
Human Races, Christian Examiner, Boston, 1850, 
8vo. (February.) 40 
ESSAY ON CLASSIFICATION. 
Part I. 
as distinct species, must have had from the beginning a different and distinct 
geographical range, frequently occupy sections of areas which are simultaneously 
inhabited by the representatives of other species, which are perfectly identical over 
the whole area. By way of an example, I would mention the European and the 
American Widgeon, (Anas lMareca' Penelope and A. americana^ or the American and the 
European Red-headed Ducks, (A. ferina and A. erytlirocephala^ which inhabit respectively 
the northern parts of the Old and New World in summer, and migrate further south 
in these same continents during winter, while the Mallard (A. Boschas) and the Scaup 
Duck (A. mania} are as common in North America as in Europe. What do these 
facts tell: That all these birds originated together somewhere, where they no longer 
occur, to establish themselves in the end within the limits they now occupy ? - or 
that they originated either in Europe or America, where, it is true, they do not live 
all together, but at least a part of them ? - or that they really originated within the 
natural boundaries they occupy ? 1 suppose with sensible readers I need only argue 
the conclusions flowing from the last supposition. If so, the American Widgeon and 
the American Red-headed Duck originated in America, and the European Widgeon 
and the European Red-headed Duck in Europe. But what of the Mallard and the 
Scaup, which are equally common upon the two continents; did they first appear in 
Europe, or in America, or simultaneously upon the two continents ? Without entering 
into further details, as I have only desired to lay clearly a distinct case before my 
readers, from which the character of the argument, which applies to the whole animal 
kingdom, may be fully understood, I say that the facts lead, step by step, to the 
inference, that such birds as the Mallard and the Scaup originated simultaneously and 
separately in Europe and in America, and that all animals originated in vast num- 
bers, indeed, in the average number characteristic of their species, over the whole of 
their geographical area, whether its surface be continuous or disconnected by sea, 
lakes, or rivers, or by differences of level above the sea, etc. The details of the 
geographical distribution of animals exhibit, indeed, too much discrimination to admit 
for a moment that it could be the result of accident, that is, the result of the 
accidental migrations of the animals or of the accidental dispersion of the seeds of 
plants. The greater the uniformity of structure of these widely distributed organized 
beings, the less probable does their accidental distribution appear. I confess that 
nothing has ever surprised me so much as to see the perfect identity of the most 
delicate microscopic structures of animals and plants, from the remotest parts of the 
world. It was this striking identity of structure in the same types, this total inde- 
pendence of the essential characteristics of animals and plants, of their distribution 
under the most extreme climatic differences known upon our globe, which led me to 
distrust the belief, then almost universal, that organized beings are influenced by 
physical causes to a degree which may essentially modify their character. Chap. I. 
LOCALIZED STRUCTURES. 
41 
SECTION XI. 
COMMUNITY OF STRUCTURE AMONG ANIMALS LIVING IN THE SAME REGIONS. 
The most interesting result of the earliest investigations of the fauna of Australia 
was the discovery of a type of animals, the Marsupialia, prevailing upon this conti- 
nental island, which are unknown in almost every other part of the world. Every 
student of Natural History knows now that there are no Quadrumana in New Holland, 
neither Monkeys, nor Makis: no Insectivora, neither Shrews, nor Moles, nor Hedgehogs; 
no true Carnivora) neither Bears, nor Weasels, nor Foxes, nor Viverras, nor Hyenas, 
nor Wild Cats; no Edentata, neither Sloths, nor Tatous, nor Ant-eaters, nor Pangolins; 
no Pachyderms, neither Elephants, nor Hippopotamuses, nor Hogs, nor Rhinoceroses, 
nor Tapirs, nor Wild Horses; no Ruminantia, neither Camels, nor Llamas, nor Deers, 
nor Goats, nor Sheep, nor Bulls, etc., and yet the Mammalia of Australia are 
almost as diversified as those of any other continent. In the words of Waterhouse,2 
who has studied them with particular care, "the Marsupialia present a remarkable 
diversity of structure, containing herbivorous, carnivorous, and insectiverous species; 
indeed, we find amongst the marsupial animals analogous representations of most of 
the other orders of Mammalia. The Quadrumana are represented by the Phelangers, 
the Carnivora by the Dasyuri, the Insectivora by the small Phascogales, the Ruminantia 
by the Kangaroos, and the Edentata by the Monotremes. The Cheiroptera are not 
represented by any known marsupial animals, and the Rodents are represented by a 
single species only; the hiatus is filled up, however, in both cases, by placental 
species, for Bats and Rodents are tolerably numerous in Australia, and, if we except 
the Dog, which it is probable has been introduced by man, these are the only pla- 
cental Mammalia found in that continent." Nevertheless, all these animals have in 
common some most striking anatomical characters, which distinguish them from all 
other Mammalia, and stamp them as one of the most natural groups of that class; 
their mode of reproduction, and the connection of the young with the mother, are 
different; so, also, is the structure of their brain, etc.3 
Now, the suggestion that such peculiarities could be produced by physical agents 
is for ever set aside by the fact that neither the birds nor the reptiles, nor, indeed, 
any other animals of New Holland, depart in such a manner from the ordinary char- 
1 Doubts are entertained respecting the origin of 
the Dingo, the only beast of prey of New Holland. 
2 Waterhouse, (G. A.,) Natural History of the 
Mammalia, London, 1848, 2 vols. 8vo., vol. i., p. 4. 
8 See Owen, (R.,) Marsupialia in Todd's Cyclo- 
pedia of Anat, and Physiol., London, 1841, 8vo., and 
several elaborate papers by himself and others, 
quoted there. 42 
ESSAY ON CLASSIFICATION. 
Part I. 
acter of tlieir representatives in other parts of the world; unless it could be shown 
that such agents have the power of discrimination, and may produce, under the same 
conditions, beings which agree and others which do not agree with those of different 
continents; not to speak again of the simultaneous occurrence in that same continent 
of other heterogeneous types of Mammalia, Bats and Rodents, which occur there 
as well as everywhere else in other continents. Nor is New Holland the only part 
of the world which nourishes animals highly diversified among themselves, and yet 
presenting common characters strikingly different from those of the other members 
of their type, circumscribed within definite geographical areas. Almost every part 
of the globe exhibits some such group either of animals or of plants, and every 
class of organized beings contains some native natural group, more or less extensive, 
more or less prominent, which is circumscribed within peculiar geographical limits. 
Among Mammalia we might quote further the Quadrumana, the representatives of 
which, though greatly diversified in the Old as well as in the New World, differ and 
agree respectively in many important points of their structure; also the Edentata of 
South America. 
Among birds, the Humming Birds, which constitute a very natural, beautiful, 
and numerous family, all of which are nevertheless confined to America only, as the 
Pheasants are to the Old World.1 Among Reptiles, the Crocodiles of the Old World 
compared to those of America. Among fishes, the family of Labyrinthici, which is 
confined to the Indian and Pacific Oceans, that of Goniodonts, which is limited to the 
fresh waters of South America, as that of Cestraciontes to the Pacific. The compar- 
ative anatomy of Insects is not sufficiently far advanced to furnish striking examples 
of this kind; among Insects, however, remarkable for their form, which are limited 
to particular regions, may be quoted the genus Mormolyce of Java, the Pneumora 
of the Cape of Good Hope, the Belostoma of North America, the Fulgora of China, 
etc. The geographical distribution of Crustacea has been treated in such a masterly 
manner by Dana, in his great work upon the Crustacea of the United States Explor- 
ing Expedition, Vol. XIII., p. 1451, that I can only refer to it for numerous examples 
of localized types of this class, and also as a model how to deal with such subjects. 
Among Worms, the Peripates of Guiana deserves to be mentioned. Among Cepha- 
lopods, the Nautilus in Amboyna. Among Gasteropods, the genus Io in the western 
waters of the United States. Among Acephala, the Trigonia in New Holland, certain 
Naiades in the United States, the Aetheria in the Nile. Among Echinoderms, the 
Pentacrinus in the West Indies, the Culcita in Zanzibar, the Amblypneustes in the 
Pacific, the Temnopleurus in the Indian Ocean, the Dendraster on the western coast 
1 What are called Pheasants in America do not 
even belong to the same family as the eastern Pheas- 
ants. The American, so-called, Pheasants are gen- 
uine Grouses. Chap. I. 
SERIAL CONNECTION AMONG ANIMALS. 
43 
of North America. Among Acalephs, the Berenice of New Holland. Among Polypi, 
the true Fungidae in the Indian and Pacific Oceans, the Renilla in the Atlantic, etc. 
Many more examples might be quoted, were our knowledge of the geographical 
distribution of the lower animals more precise. But these will suffice to show that 
whether high or low, aquatic or terrestrial, there are types of animals remarkable for 
their peculiar structure which are circumscribed within definite limits, and this locali- 
zation of special structures is a striking confirmation of the view expressed already 
in another connection, that the organization of animals, whatever it is, may be 
adapted to various and identical conditions of existence, and can in no way be con- 
sidered as originating from these conditions. 
SECTION XII. 
SERIAL CONNECTION IN THE STRUCTURE OF AMIMALS WIDELY SCATTERED UPON THE 
SURFACE OF OUR GLOBE. 
Ever since I have become acquainted with the reptiles inhabiting different parts 
of the world, I have been struck with a remarkable fact, not yet noticed by natu- 
ralists, as far as I know, and of which no other class exhibits such striking examples. 
This fact is that among Saurians, as well as among Betrachians, there are families, the 
representatives of which, though scattered all over the globe, form the most natural 
connected series, in which every link represents one particular degree of development. 
The Scincoids,1 among Saurians, are one of these families. It contains about one 
hundred species, referred by Dumeril and Bibron to thirty-one genera, which, in the 
development of their organs of locomotion, exhibit most remarkable combinations, 
illustrated in a diagram, on the following page. 
Fully to appreciate the meaning of this diagram, it ought to be remembered, 
that the animals belonging to this family are considered here in two different points 
of view. In the first place, their zoological relations to one another are expressed 
by the various combinations of the structure of their legs; some having four legs, 
and these are the most numerous, others only two legs, which are always the hind 
legs, and others still no legs at all. Again these legs may have only one toe, or 
two, three, four, or five toes, and the number of toes may vary between the fore 
and hind legs. The classification adopted here is based upon these characters. In 
1 For the characters of the family, see Dumeril See also Cocteau, Etudes sur les Scincoides, Paris, 
et Bibron, Erpetologie generale, vol. 5, p. 511. 1836, 4to. fig. 44 
ESSAY ON CLASSIFICATION. 
Part I. 
the second place, the geographical distribution is noticed. But it is at once apparent 
that the home of these animals stands in no relation whatsoever to their zoological 
arrangement. On the contrary, the most remote genera may occur in the same 
country, while the most closely related may live far apart. 
GENERA WITH FOUR LEGS. 
Tropidophorus, 1 species, Cochin-China. 
Scincus, 1 sp., Syria, North and West Africa. 
Sphenops, 1 sp., Egypt. 
Diploglossus, 6 sp., West Indies and Brazils. 
Amphiglossus, 1 sp., Madagascar. 
Gongylus, with 7 sub-genera: 
Gongylus, 2 sp., Southern Europe, Egypt, Teneriffe, Isle de France. 
Eumeces, 11 sp., East and West Indies, South America, Vanikoro, 
New Ireland, New Guinea, Pacific Islands. 
Euprepes, 13 sp., West coast of Africa, Cape of Good Hope, Egypt, 
Abyssinia, Seychelles, Madagascar, New Guinea, East Indies, 
Sunda Islands, Manilla. 
Plestiodon, 5 sp., Egypt, Algiers, China, Japan, United States. 
Lygosoma, 19 sp., New Holland, New Zealand, Java, New Guinea, 
Timor, East Indies, Pacific Islands, United States. 
Leiolopisma, 1 sp., Mauritius and Manilla. 
Tropidolopisma, 1 sp., New Holland. 
Cydodus, 3 sp., New Holland and Java. 
Trachysaurus, 1 sp., New Holland. 
Ablepharus, 4 sp., Southeastern Europe, New Holland, Pacific Islands. 
With five toes to the fore feet, as 
well as to the hind feet: 
With five toes to the fore feet and four toes to the hind feet: Campsodactylus, 1 sp., Bengal. 
With four toes to the fore feet and 
five toes to the hind feet: 
Heteropus, 3 sp., Africa, New Holland, Isle de France. 
Gymnophthalmus, 1 sp., W. Indies and Brazil. 
With four toes to the fore feet and 
four toes to the hind feet: 
Tetradactylus, 1 sp., New Holland. The genus Chalcides of the allied 
family Chalcidioids, exhibits another example of this combination. 
With four toes to the fore feet and three toes to the hind feet: No examples known of this combination. 
With three toes to the fore feet and four toes to the hind feet: Not known. 
With three toes to the fore feet and 
three toes to the hind feet: 
Hemiergis, 1 sp., New Holland. 
Seps, 1 sp., S. Europe and N. Africa. 
Nessia, 1 sp., Origin unknown. 
With three toes to the fore feet and two toes to the hind feet: Not known. 
With two toes to the fore feet and 
three toes to the hind feet: 
Heteromeles, 1 sp., Algiers. 
Lerista, 1 sp., New Holland. 
With two toes to the fore feet and two toes to the hind feet: Chelomeles, 1 sp., New Holland. 
With two toes to the fore feet and one toe to the hind feet: Brachymeles, 1 sp., Philippine Islands. 
With one toe to the fore feet and two toes to the hind feet: Brachystopus, 1 sp., South Africa. 
With one toe to the fore feet and one toe to the hind feet: Evesia, 1 sp., Origin unknown. Chap. I. 
SERIAL CONNECTION AMONG ANIMALS. 
45 
GENERA WITH ONLY TWO LEGS. 
No representatives are known with fore legs only; but this structural combination occurs in the allied 
family of the Chalcidioids. The representatives with hind legs only, present the following combinations: - 
With two toes: Scelotes, 1 sp., Cape Good Hope. 
With one toe: Propeditus, 1 sp., Cape Good Hope and New Holland. 
Ophiodes, 1 sp., South America. 
Hysteropus, 1 sp., New Holland. 
Lialis, 1 sp., New Holland. 
Dibamus, 1 sp., New Guinea. 
GENERA WITHOUT ANY LEGS. 
Anguis, 1 sp., Europe, Western Asia, Northern Africa. 
Ophiomorus, 1 sp., Morea, Southern Russia, and Algiers. 
Acontias, 1 sp., Southern Africa, Cape Good Hope. 
Typhlina, 1 sp., Southern Africa, Cape Good Hope. 
Who can look at this diagram, and not recognize in its arrangement the combi- 
nations of thought? This is so obvious, that while considering it one might almost 
overlook the fact, that while it was drawn up to classify animals preserved in the 
Museum of the Jardin des Plantes in Paris, it is in reality inscribed in Nature by 
these animals themselves, and is only read off when they are brought together, and 
compared side by side. But it contains an important element for our discussion: 
the series is not built up of equivalent representatives in its different terms, some 
combinations being richly endowed, others numbering a few, or even a single genus, 
and still others being altogether disregarded; such freedom indicates selection, and 
not the working of the law of necessity. 
And if from a contemplation of this remarkable series we turn our attention to 
the indications relating to the geographical distribution of these so closely linked 
genera, inscribed after their names, we perceive at once, that they are scattered all 
over the globe, but not so that there could be any connection between the combina- 
tions of their structural characters and their homes. The types without legs are 
found in Europe, hi Western Asia, in Northern Africa, and at the Cape of Good 
Hope; the types with hind legs only, and with one single toe, at the Cape of 
Good Hope, in South America, New Holland, and New Guinea; those with two toes 
at the Cape of Good Hope only. Among the types with four legs the origin of those 
with but one toe to each foot is unknown, those with one toe in the fore foot and 
two in the hind foot are from South Africa, those with two toes in the fore foot and 
one in the hind foot occur in the Philippine Islands, those with two toes to all four 
feet in New Holland, those with three toes to the hind feet and two to the fore feet 46 
ESSAY ON CLASSIFICATION. 
Part 1. 
in Algiers and New Holland; none are known with three toes to the fore feet and 
two to the liind feet. Those with three toes to the four feet inhabit Europe, North- 
ern Africa, and New Holland. There are none with three and four toes, either in 
the fore feet or in the hind feet. Those with four toes to the four feet live in 
New Holland; those with five toes to the fore feet and four to the hind feet, in 
Bengal, and with four toes in the fore feet and five in the hind feet, in Africa, 
the West Indies, the Brazils, and New Holland. Those with five toes to all four 
feet have the widest distribution, and yet they are so scattered that no single zoolog- 
ical province presents any thing like a complete series; on the contrary, the mixture 
of some of the representatives with perfect feet with others which have them rudi- 
mentary, in almost every fauna, excludes still more decidedly the idea of an influence 
of physical agents upon this development. 
Another similar series, not less striking, may be traced among the Batrachians, 
for the characters of which I may refer to the works of Holbrook, Tschudi, and 
Baird,1 even though they have not presented them in this connection, as the charac- 
teristics of the genera will of themselves suggest their order, and further details upon 
this subject would be superfluous for my purpose, the more so, as I have already 
discussed the gradation of these animals elsewhere.2 
Similar series, though less conspicuous and more limited, may be traced in every 
class of the animal kingdom, not only among the living types, but also among the 
representatives of past geological ages, which adds to the interest of such series in 
showing, that the combinations include not only the element of space, indicating 
omnipresence, but also that of time, which involves prescience. The series of Crinoids, 
that of Brachiopods through all geological ages, that of the Nautiloids, that of 
Ammonitoids from the Trias to the Cretaceous formation inclusive, that of Trilobites 
from the lowest beds up to the Carboniferous period, that of Ganoids through all 
formations; then again among living animals in the class of Mammalia, the series of 
Monkeys in the Old World especially, that of Carnivora from the Seals, through the 
Plantigrades, to the Digitigrades; in the class of Birds, that of the Wading Birds, 
and that of the Gallinaceous Birds; in the class of Fishes, that of Pleuronectidm and 
Gadoids, that of Skates and Sharks; in the class of Insects, that of Lepidoptera from 
the Tineina to the Papilionina; in the class of Crustacea, that of the Decapods in 
particular; in the class of Worms, that of the Nudibranchiata or that of the Dorsibran- 
1 Holbrook, (J. E.,) North American Her- 
petology, Philadelphia, 1842, 4to.; 5th vol. - 
Tschudi, (J. J.) Classification der Batrachier, 
Neuchatel, 1838, 4to.- Baird, (Sp. F.) Revision 
of the North American Tailed Batrachia, Journal 
Acad. Nat. Science, of Philadelphia, 2d series, 
vol. L, 1849, 4to. 
2 Agassiz, (L.,) Twelve Lectures on Compara- 
tive Embryology, Boston, 1849, 8vo.; p. 8. Chap. I. 
SIZE OF ANIMALS. 
47 
chiata especially; in the class of Cephalopoda, that of the Sepioids; in the class of 
Gasteropoda, that of the Nudibranchiata in particular; in the class of Acephala, that 
of the Ascidians and that of the Oysters in the widest sense; in the class of Echino- 
derms, those of Holothuriae and Asterioids; in the class of Acalephs, that of the 
Hydroids; in the class of Polyps, that of the Halcyonoids, of the Atraeoids, etc., etc., 
deserve particular attention, and may be studied with great advantage in reference 
to the points under consideration. For everywhere do we observe in them, with 
reference to space and to time, the thoughtful combinations of an active mind. 
But it ought not to be overlooked, that while some types represent strikingly con- 
nected series, there are others in which nothing of the kind seems to exist, and the 
diversity of which involves other considerations. 
SECTION XIII. 
RELATION BETWEEN THE SIZE OF ANIMALS, AND THEIR STRUCTURE. 
The relation between the size and structure of animals has been very little 
investigated, though even the most superficial survey of the animal kingdom may 
satisfy any one, that there is a decided relation between size and structure among 
them. Not that I mean to assert that size and structure form parallel series, or 
that all animals of one branch, or even those of the same class or the same order, 
agree very closely with one another in reference to size. This element of their 
organization is not defined within those limits, though the Vertebrata, as a whole, 
are larger than either Articulata, Mollusks, or Radiata; though Mammalia are larger 
than Birds, Crustacea larger than Insects; though Cetacea are larger than Herbivora, 
these larger than Carnivora, etc. The true limit at which, in the organization of 
animals, size acquires a real importance, is that of families, that is, the groups which 
are essentially distinguished by their form, as if form and size were correlative as 
far as the structure of animals is concerned. The representatives of natural families 
are indeed closely similar in that respect; the extreme differences are hardly any- 
where tenfold within these limits, and frequently only double. A few examples, 
selected among the most natural families, will show this. Omitting mankind, on 
account of the objections which might be made against the idea that it embraces 
any original diversity, let us consider the different families of Monkeys, of Bats, of 
Insectivora, of Carnivora, of Rodents, of Pachyderms, of Ruminants, etc., among 
Birds, the Vultures, the Eagles, the Falcons, the Owls, the Swallows, the Finches, the 
Warblers, the Humming Birds, the Doves, the Wrens, the Ostriches, the Herons, 48 
ESSAY ON CLASSIFICATION. 
Part I. 
the Plovers, the Gulls, the Ducks, the Pelicans; among Reptiles, the Crocodiles, the 
different families of Chelonians, of Lizards, of Snakes, the Frogs proper, the Toads, 
etc.; among Fishes, the Sharks and Skates, the Herrings, the Codfishes, the Cyprin- 
nodonts, the Chaetodonts, the Lophobranchii, the Ostracionts, etc.; among Insects, the 
Sphingoidae or the Tineina, the Longicorns or the Coccinellina, the Bomboidse or the 
Brachonidse; among Crustacea, the Cancroidea or the Pinnotheroidse, the Limuloidse 
or the Cypridoidm, and the Rotifera;1 among Worms, the Dorsibranchiata or the 
Naioidae; among Mollusks, the Stromboidm or the Buccinoidae, the Helicinoidae or the 
Limnasoidae, the Chamacea or the Cycladoidae; among Radiata, the Asterioidae and 
the Ophiuroidae, the Hydroids and the Discophorm, the Astraeoidae and the Actinioidae. 
Having thus recalled some facts which go to show what are the limits within 
which size and structure are more directly connected,2 it is natural to infer, that 
since size is such an important character of species, and extends distinctly its cycle 
of relationship to the families or even further, it can as little be supposed to be 
determined by physical agents as the structure itself with which it is so closely 
connected, both bearing similar relations to these agents. 
Life is regulated by a quantitative element in the structure of all organized 
beings, which is as fixed and as precisely determined as every other feature depend- 
ing more upon the quality of the organs or their parts. This shows the more 
distinctly the presence of a specific, immaterial principle in each kind of animals 
and plants, as all begin their existence in the condition of ovules of a microscopic 
size, exhibiting in all a wonderful similarity of structure. And yet these primitive 
ovules, so identical at first in their physical constitution, never produce any thing 
different from the parents; all reach respectively, through a succession of unvarying 
changes, the same final result, the reproduction of a new being identical with the 
parents. How does it then happen, that, if physical agents have such a powerful 
influence in shaping the character of organized beings, we see no trace of it in the 
innumerable instances in which these ovules are discharged in the elements in which 
they undergo their further development, at a period when the germ they contain, 
1 See Dana's Crustacea, p. 1409 and 1411. 
2 These remarks about the average size of ani- 
mals in relation to their structure, cannot fail to 
meet with some objections, as it is well known, 
that under certain circumstances, man may modify 
the normal size of a variety of plants and of 
domesticated animals, and that even in their natural 
state occasional instances of extraordinary sizes 
occur. But this neither modifies the character- 
istic average, nor is it a case which has the 
least bearing upon the question of origin or even 
the maintenance of any species, but only upon 
individuals, respecting which more will be found in 
Sect. 16. Moreover, it should not be overlooked 
that there are limits to these variations, and that 
though animals and plants may be placed under 
influences conducive to a more or less voluminous 
growth, yet it is chiefly under the agency of man, 
that such changes reach their extremes. (See also 
Sect. 15.) Chap. I. 
SIZE AND THE ELEMENTS. 
49 
has not yet assumed any of those more determined characteristics which distinguish 
the full-grown animal or the perfect plant ? Do physicists know a law of the 
material world which presents any such analogy to these phenomena, that it could 
be considered as accounting for them? 
In this connection it should be further remembered, that these cycles of size 
characteristic of different families, are entirely different for animals of different types, 
though living together under identical circumstances. 
SECTION XIV. 
RELATIONS BETWEEN THE SIZE OF ANIMALS, AND THE MEDIUMS IN WHICH THEY LIVE. 
It has just been remarked, that animals of different types, even when living 
together, are framed in structures of different size. Yet, life is so closely combined 
with the elements of nature, that each type shows decided relations, within its own 
limits, to these elements as far as size is concerned.1 The aquatic Mammalia, as a 
whole, are larger than the terrestrial ones; so are the aquatic Birds, and the aquatic 
Reptiles. In families which are essentially terrestrial, the species which take to the 
water are generally larger than those which remain permanently terrestrial, as for 
instance, the Polar Bear, the Beaver, the Coypu, and the Capivara. Among the 
different families of aquatic Birds, those of their representatives which are more ter- 
restrial in their habits are generally smaller than those which live more permanently 
in water. The same relation is observed in the different families of Insects which 
number aquatic and terrestrial species. It is further remarkable, that among aquatic 
animals, the fresh water types are inferior in size to the marine ones; the marine 
Turtles are all larger than the largest inhabitants of our rivers and ponds, the more 
aquatic Trionyx larger than the Emyds and among these the more aquatic Chelydra 
larger than the true Emys, and these generally larger than the more terrestrial 
Clemmys or the Cistudo. The class of Fishes has its largest representatives in the 
sea; fresh water fishes are on the whole dwarfs, in comparison to their marine 
relatives, and the largest of them, our Sturgeons and Salmons, go to the sea. The 
same relations obtain among Crustacea; to be satisfied of the fact, we need only 
compare our Crawfishes with the Lobsters, our Apus with Limulus, etc. Among 
1 Geoffroy St. Hilaire, (Isid.,) Recherches 
zoologiques et physiologiques sur les variations 
de la taille chez les Animaux et dans les races 
humaines, Paris, 1831, 4to. - See also my paper 
upon the Natural Relations between Animals and the 
Elements, etc., quoted above, p. 32. 50 
ESSAY ON CLASSIFICATION. 
Part I. 
Worms, the Earthworms and Leeches furnish a still wider range of comparisons 
when contrasted with the marine types. Among Gasteropods and Acephala, this 
obtains to the same extent; the most gigantic Ampullariae and Anodontae are small 
in comparison to certain Fusus, Voluta, Tritonium, Cassis, Strombus, or to the 
Tridacna. Among Radiata even, which are all marine, with the exception of the 
single genus Hydra, this rule holds good, as the fresh water Hydroids are among the 
smallest Acalephs known. 
This coincidence, upon such an extensive scale, seems to be most favorable to 
the view that animals are modified by the immediate influence of the elements; 
yet I consider it as affording one of the most striking proofs that there is no causal 
connection between them. Were it otherwise, the terrestrial and the aquatic repre- 
sentatives of the same family could not be so similar as they are in all their 
essential characteristics, which actually stand in no relation whatsoever to these 
elements. What constitutes the Bear in the Polar Bear, is not its adaptation to an 
aquatic mode of existence. What makes the Whales Mammalia, bears no relation to 
the sea. What constitutes Earthworms, Leeches, and Eunice members of one class, 
has no more connection with their habitat, than the peculiarities of structure which 
unite Man, Monkeys, Bats, Lions, Seals, Beavers, Mice, and Whales into one class. 
Moreover, animals of different types living in the same element have no sort of 
similarity, as to size. The aquatic Insects, the aquatic Mollusks fall in with the 
average size of their class, as well as the aquatic Reptiles and the aquatic Birds, or 
the aquatic Mammalia; but there is no common average for either terrestrial or 
aquatic animals of different classes taken together, and in this lies the evidence that 
organized beings are independent of the mediums in which they live, as far as their 
origin is concerned, though it is plain that when created they were made to suit 
the element in which they were placed. 
To me these facts show, that the phenomena of life are manifested in the 
physical world, and not through or by it; that organized beings are made to 
conquer and assimilate to themselves the materials of the inorganic world; that 
they maintain their original characteristics, notwithstanding the unceasing action of 
physical agents upon them. And I confess I cannot comprehend how beings, so 
entirely independent of these influences, could be produced by them. Chap. I. 
IMMUTABILITY OF SPECIES. 
51 
SECTION XV. 
PERMANENCY OF SPECIFIC PECULIARITIES IN ALL ORGANIZED BEINGS. 
It was a great step in the progress of science when it was ascertained that 
species have fixed characters, and that they do not change in the course of time. 
But this fact, for which we are indebted to Cuvier,1 has acquired a still greater 
importance since it has also been established, that even the most extraordinary 
changes in the mode of existence and in the conditions under which animals may be 
placed, have no more influence upon their essential characters than the lapse of time. 
The facts bearing upon these two subjects are too well known now to require 
special illustration. I will, therefore, allude only to a few points, to avoid even the 
possibility of a misapprehension of my statements. That animals of different geo- 
logical periods differ specifically, en masse, from those of preceding or following forma- 
tions, is a fact satisfactorily ascertained. Between two successive geological periods, 
then, changes have taken place among animals and plants. But none of those pri- 
mordial forms of life, which naturalists call species, are known to have changed 
during any of these periods. It cannot be denied, that the species of different 
successive periods are supposed by some naturalists to derive their distinguishing 
features from changes which have taken place in those of preceding ages; but this 
is a mere supposition, supported neither by physiological nor by geological evidence, 
and the assumption that animals and plants may change in a similar manner during 
one and the same period, is equally gratuitous. On the contrary, it is known by 
the evidence furnished by the Egyptian monuments, and by the most careful com- 
parison between animals found in the tombs of Egypt with living specimens of the 
same species obtained in the same country, that there is not the shadow of a differ- 
ence between them, for a period of about five thousand years. These comparisons, 
first instituted by Cuvier, have proved, that as far as it has been possible to carry 
back the investigation, it does not afford the beginning of an evidence that species 
change in the course of time, if the comparisons be limited to the same great 
cosmic epoch. Geology only shows that at different periods2 there have existed 
1 Cuvier, (G.,) Recherches sur les ossements 
fossiles, etc., Nouv., edit. Paris, 1821, 5 vols., 4to., 
fig., vol. i., sur 1'Ibis, p. cxli. 
2 I trust no reader will be so ignorant of the 
facts here alluded to, as to infer from the use of 
the word " period " for different eras and epochs of 
great length, each of which is characterized by dif- 
ferent animals, that the differences these animals ex- 
hibit, is in itself evidence of a change in the species. 
The question is, whether any changes take place 
during one or any of these • periods. It is almost 
incredible how loosely some people will argue upon 52 
ESSAY ON CLASSIFICATION. 
Part I. 
different species; but no transition from those of a preceding into those of the 
following epoch has ever been noticed anywhere; and the question alluded to here is 
to be distinguished from that of the origin of the differences in the bulk of species 
belonging to two different geological eras. The question we are now examining 
involves only the fixity or mutability of species during one epoch, one era, one 
period in the history of our globe. And nothing furnishes the slightest argument in 
this point from a want of knowledge of the facts, 
even though they seem to reason logically. A dis- 
tinguished physicist has recently taken up this sub- 
ject of the immutability of species, and called in 
question the logic of those who uphold it. I will 
put his argument into as few words as possible, 
and show, I hope, that it does not touch the case. 
" Changes are observed from one geological period 
to another; species which do not exist at an earlier 
period are observed at a later period, while the for- 
mer have disappeared; and though each species may 
have possessed its peculiarities unchanged for a lapse 
of time, the fact that when long periods are con- 
sidered, all those of an earlier period are replaced 
by new ones at a later period, proves that species 
change in the end, provided a sufficiently long period 
of time is granted." I have nothing to object to the 
statement of facts, as far as it goes, but I maintain 
that the conclusion is not logical. It is true that 
species are limited to particular geological epochs; 
it is equally true that, in all geological formations, 
those of successive periods are different, one from 
the other. But because they so differ, does it fol- 
low that they have changed, and not been exchanged 
for, or replaced by others ? The length of time 
taken for the operation has nothing to do with the 
argument. Granting myriads of years for each pe- 
riod, no matter how many or how few, the question 
remains simply this: When the change takes place, 
does it take place spontaneously, under the action of 
physical agents, according to their law, or is it pro- 
duced by the intervention of an agency not in that 
way at work before or afterwards ? A comparison 
may explain my view more fully. Let a lover of 
the fine arts visit a museum arranged systematically, 
and in which the works of the different schools are 
placed in chronological order; as he passes from one 
room to another, he beholds changes as great as those 
the palaeontologist observes in passing from one sys- 
tem of rocks to another. But because these works 
bear a closer resemblance as they belong to one or 
the other school, or to periods following one another 
closely, would the critic be in any way justified 
in assuming that the earlier works have changed 
into those of a later period, or to deny that they 
are the works of artists living and active at the 
time of their production ? The question about the 
immutability of species is identical with this sup- 
posed case. It is not because species have lasted 
for a longer or shorter time in past ages, that nat- 
uralists consider them as immutable, but because in 
the whole series of geological ages, taking the entire 
lapse of time which has passed since the first intro- 
duction of animals or plants upon earth, not the 
slightest evidence has yet been produced that species 
are actually transformed one into the other. We 
only know that they are different at different periods, 
as are works of art of different periods and of differ- 
ent schools ; but as long as we have no other data to 
reason upon than those geology has furnished, to this 
day, it is as unphilosophical and illogical, because 
such differences exist, to assume that species do 
change, and have changed, that is, are transformed, 
or have been transformed, as it would be to main- 
tain that works of art change in the course of time. 
We do not know how organized beings have origi- 
nated, it is true; no naturalist can be prepared to 
account for their appearance in the beginning, or for 
their difference in different periods; but enough is 
known to repudiate the assumption of their transmu- 
tation, as it does not explain the facts, and shuts out 
further attempts at proper investigations. See Ba- 
den Powell's Essays, quoted above; p. 412, et 
seq., and Essay 3d, generally. Chap. I. 
IMMUTABILITY OF SPECIES. 
53 
favor of their mutability; on the contrary, every modern investigation1 has only 
gone to confirm the results first obtained by Cuvier, and his views that species are 
fixed. 
It is something to be able to show by monumental evidence, and by direct com- 
parison, that animals and plants have undergone no change for a period of about 
five thousand years.2 This result has had the greatest influence upon the progress 
of science, especially with reference to the consequences to be drawn from the occur- 
rence in the series of geological formations of organized beings as highly diversified 
in each epoch as those of the present day;3 it has laid the foundation for the con- 
viction, now universal among well informed naturalists, that this globe has been in 
existence for innumerable ages, and that the length of time elapsed since it first 
became inhabited cannot be counted in years. Even the length of the period to 
which we belong is still a problem, notwithstanding the precision with which certain 
systems of chronology would fix the creation of man.4 There are, however, many 
circumstances which show that the animals now living* have been for a much longer 
period inhabitants of our globe than is generally supposed. It has been possible to 
trace the formation and growth of our coral reefs, especially in Florida,6 with suffi- 
cient precision to ascertain that it must take about eight thousand years for one of 
those coral walls to rise from its foundation to the level of the surface of the ocean. 
There are, around the southernmost extremity of Florida alone, four such reefs con- 
centric with one another, which can be shown to have grown up, one after the 
other. This gives for the beginning of the first of these reefs an age of over thirty 
thousand years; and yet the corals by which they were all built up are the same 
identical species in all of them. These facts, then, furnish as direct evidence as we 
can obtain in any branch of physical inquiry, that some, at least, of the species of 
animals now existing, have been in existence over thirty thousand years, and have 
not undergone the slightest change during the whole of that period.6 And yet these 
1 Runth, Recherches sur les plantes trouvees 
dans les tombeaux egyptiens, Ann. des scien. nat., vol. 
viii., 1826, p. 411. 
2 It is not for me to discuss the degree of reli- 
ability of the Egyptian chronology; but as far as it 
goes, it shows that from the oldest periods ascer- 
tained, animals have been what they are now. 
3 See my paper upon The Primitive Diversity, 
etc., quoted above, p. 25. 
4 Nott & Gliddon, Types of Mankind, p. 653. 
6 See my paper upon the Reefs of Florida, soon 
to be published in the Reports of the United States 
Coast Survey, extracts of which are already printed 
in the Report for 1851, p. 145. 
6 Those who feel inclined to ascribe the differ- 
ences which exist between species of different geo- 
logical periods to the modifying influence of physi- 
cal agents, and who look to the changes now going 
on among the living for the support of such an 
opinion, and may not be satisfied that the facts just 
mentioned are sufficient to prove the immutability 
of species, but may still believe that a longer period 
of time would yet do what thirty thousand years 
have not done, I beg leave to refer, for further con- 54 
ESSAY ON CLASSIFICATION. 
Part I. 
four concentric reefs are only the most distinct of that region; others, less exten- 
sively investigated thus far, lie to the northward; indeed, the whole peninsula of 
Florida consists altogether of coral reefs annexed to one another in the course of 
time, and containing only fragments of corals and shells, etc., identical with those 
now living upon that coast. Now, if a width of five miles is a fair average for one 
coral reef growing under the circumstances under which the concentric reefs of 
Florida are seen now to follow one another, and this regular succession should extend 
only as far north as Lake Ogeechobee, for two degrees of latitude, this would give 
about two hundred thousand years for the period of time which was necessary for 
that part of the peninsula of Florida which lies south of Lake Ogeechobee to rise 
to its present southern extent above the level of the sea, and during which no 
changes have taken place in the character of the animals of the Gulf of Mexico. 
It is very prejudicial to the best interests of science to confound questions that 
are entirely different, merely for the sake of supporting a theory; yet this is con- 
stantly done, whenever the question of the fixity of species is alluded to. A few 
more words upon this point will, therefore, not be out of place here. 
1 will not enter into a discussion upon the question whether any species is found 
identically the same in two successive formations, as I have already examined it at 
full length elsewhere,1 and it may be settled finally one way or the other, without 
affecting the proposition now under consideration; for it is plain, that if such identity 
could be proved, it would only show more satisfactorily how tenacious species are in 
their character, to continue to live through all the physical changes which have 
taken place between two successive geological periods. Again, such identity once 
proved, would leave it still doubtful whether their representatives in two successive 
epochs are descendants one of the other, as we have already strong evidence in favor 
of the separate origin of the representatives of the same species in separate geo- 
graphical areas.2 The case of closely allied, but different species occurring in succes- 
sive periods, yet limited respectively in their epochs, affords, in the course of time, a 
parallel to the case of closely allied, so-called, representative species occupying differ- 
ent areas in space, which no sound naturalist would suppose now to be derived one 
from the other. There is no more reason to suppose equally allied species following 
one another in time to be derived one from the other; and all that has been said 
sideration, to the charming song of Chamisso, entitled 
Tragishe Geschichte, and beginning as follows: 
's war Einer dem's zu Herzen sing, 
o o 
1 Agassiz, (L.,) Coquilles tertiaires reputees 
identiques avec les especes vivantes, Nouv. Mem. de 
la Soc. Helv. des sc. nat. Neuchatel, 1845, vol. 7, 
4to. fig. - Agassiz, (L.,) Etudes critiques sur les 
Mollusques fossiles, Neuchatel, 1831-45, 4to. fig.- 
Agassiz, (L.,) Monographies d'Echinodermes vivans 
et fossiles, Neuchatel, 1838-42, 4 nos., 4to. fig. - 
Agassiz, (L.,) Recherches sur les Poissons fossiles, 
Neuchatel, 1833-44, 5 vols., 4to., atlas, fol. 
2 See Sect. 10, where the case of representative 
species is considered. Chap. I. 
IMMUTABILITY OF SPECIES. 
55 
in preceding paragraphs respecting the differences observed between species occurring 
in different geographical areas, applies with the same force to species succeeding 
each other in the course of time. 
When domesticated animals and cultivated plants are mentioned as furnishing 
evidence of the mutability of species, the circumstance is constantly overlooked or 
passed over in silence, that the first point to be established respecting them, in order 
to justify any inference from them against the fixity of species, would be to show 
that each of them has originated from one common stock, which, far from being the 
case, is flatly contradicted by the positive knowledge we have that the varieties of 
several of them, at least, are owing to the entire amalgamation of different species.1 
The Egyptian monuments show further that many of those so-called varieties which 
are supposed to be the product of time, are as old as any other animals which have 
been known to man; at all events, we have no tradition, no monumental evidence 
of the existence of any wild animal older than that which represents domesticated 
animals, already as different among themselves as they are now.2 It is, therefore, 
quite possible that the different races of domesticated animals were originally distinct 
species, more or less mixed now, as the different races of men are. Moreover, 
neither domesticated animals nor cultivated plants, nor the races of men, are the 
proper subjects for an investigation respecting the fixity or mutability of species, as 
all involve already the question at issue in the premises which are assumed in intro- 
ducing them as evidence in the case. With reference to the different breeds of our 
domesticated animals, which are known to be produced by the management of man, 
as well as certain varieties of our cultivated plants, they must be well distinguished 
from permanent races, which, for aught we know, may be primordial; for breeds 
are the result of the fostering care of man; they are the product of the limited 
influence and control the human mind has over organized beings, and not the free 
product of mere physical agents. They show, therefore, that even the least impor- 
tant changes which may take place during one and the same cosmic period among 
animals and plants are controlled by an intellectual power, and do not result from 
the immediate action of physical causes. 
So far, then, from disclosing the effects of physical agents, whatever changes are 
known to take place in the course of time among organized beings appear as the 
result of an intellectual power, and go, therefore, to substantiate the view that all 
the differences observed among finite beings are ordained by the action of the 
Supreme Intellect, and not determined by physical causes. This position is still 
more strengthened when we consider that the differences which exist between differ- 
ent races of domesticated animals and the varieties of our cultivated plants, as well 
1 Our fowls, for instance. 
2 Nott & Gliddon, Types of Mankind, p. 386. 56 
ESSAY ON CLASSIFICATION. 
Part I. 
as among the races of men, are permanent under the most diversified climatic influ- 
ences ; a fact, which the extensive migrations of the civilized nations daily proves more 
extensively, and which stands in direct contradiction to the supposition that such or 
similar influences could have produced them. 
When considering the subject of domestication, in particular, it ought further to 
be remembered, that every race of men has its own peculiar kinds of domesticated 
animals and of cultivated plants, which exhibit much fewer varieties among them 
in proportion as those races of men have had little or no intercourse with other 
races, than the domesticated animals of those nations which have been formed by the 
mixture of several tribes. 
It is often stated that the ancient philosophers have solved satisfactorily all the 
great questions interesting to man, and that modern investigations, though they have 
grasped with new vigor, and illuminated with new light, all the phenomena of the 
material world, have added little or nothing in the field of intellectual progress. Is 
this true ? There is no question so deeply interesting to man as that of his own 
origin, and the origin of all things. And yet antiquity had no knowledge concerning 
it; things were formerly believed either to be from eternity, or to have been created 
at one time. Modern science, however, can show, in the most satisfactory manner, 
that all finite beings have made their appearance successively and at long intervals, 
and that each kind of organized beings has existed for a definite period of time in 
past ages, and that those now living are of comparatively recent origin. At the 
same time, the order of their succession and their immutability during such cosmic 
periods, show no causal connection with physical agents and the known sphere of 
action of these agents in nature, but argue in favor of repeated interventions on 
the part of the Creator. It seems really surprising, that while such an intervention 
is admitted by all, except the strict materialists, for the establishment of the laws 
regulating the inorganic world, it is yet denied by so many physicists, with reference 
to the introduction of organized beings at different successive periods. Does this not 
rather go to show the imperfect acquaintance of these investigators with the condi- 
tions under which life is manifested, and with the essential difference there is between 
the phenomena of the organic and those of the physical world, than to furnish any 
evidence that the organic world is the product of physical causes? Chap. I. 
HABITS OF ANIMALS. 
57 
SECTION XVI. 
RELATIONS BETWEEN ANIMALS AND PLANTS AND THE SURROUNDING WORLD. 
Every animal and plant stands in certain definite relations to the surrounding 
world, some however, like the domestic animals and cultivated plants, being capable 
of adapting themselves to various conditions more readily than others; but even 
this pliability is a characteristic feature. These relations are highly important in a 
systematic point of view, and deserve the most careful attention, on the part of 
naturalists. Yet, the direction zoological studies have taken since comparative anat- 
omy and embryology began to absorb almost entirely the attention of naturalists, 
has been very unfavorable to the investigation of the habits of animals, in which 
their relations to one another and to the conditions under which they live, are more 
especially exhibited. We have to go back to the authors of the preceding century,1 
for the most interesting accounts of the habits of animals, as among modern writers 
there are few who have devoted their chief attention to this subject.2 So little, 
indeed, is its importance now appreciated, that the students of this branch of natural 
history are hardly acknowledged as peers by their fellow investigators, the anat- 
omists and physiologists, or the systematic zoologists. And yet, without a thorough 
knowledge of the habits of animals, it will never be possible to ascertain with any 
degree of precision the true limits of all those species which descriptive zoologists 
have of late admitted with so much confidence in their works. And after all, what 
does it matter to science that thousands of species more or less, should be described 
and entered in our systems, if we know nothing about them ? A very common 
defect of the works relating to the habits of animals has no doubt contributed to 
detract from their value and to turn the attention in other directions: their purely 
anecdotic character, or the circumstance that they are too frequently made the 
occasion for narrating personal adventures. Nevertheless, the importance of this 
1 Reaumur, (R. Ant. de,) Memoires pour 
servir a 1'histoire des Insectes, Paris, 1834-42, 6 vol. 
4to. fig. - Rosel, (A. J.,) Insectenbelustigungen, 
Nurnberg, 1746-61, 4 vols. 4to. fig. - Buffon, 
(G. L. LeClerc de,) Histoire naturelie generale 
et particuliere, Paris, 1749, 44 vols. 4to. fig. 
2 Audubon, (J. J.,) Ornithological Biography, 
or an Account of the Habits of the Birds of the 
United States of America, Edinburgh, 1831-49, 
5 vols. 8vo. - Kirby, (W.,) and Spence, (W.,) 
An Introduction to Entomology, London, 1818-2 G, 
4 vols. 8vo. fig. - Lenz, (II. O.,) Gemeinniitzige 
Naturgeschichte, Gotha, 1835, 4 vols. 8vo.- Rat- 
zenburg, (J. Tn. Ch.,) Die Forst-Insekten, Ber- 
lin, 1837-44, 3 vols. 4to. fig., and supplement.- 
Harris, (T. W.,) Report on the Insects injurious 
to Vegetation, Cambridge, 1841, 1 vol. 8vo.; the 
most important work on American Insects. 58 
ESSAY ON CLASSIFICATION. 
Part I. 
kind of investigation can hardly be overrated; and it would be highly desirable that 
naturalists should turn again their attention that way, now that comparative anatomy 
and physiology, as well as embryology, may suggest so many new topics of inquiry, 
and the progress of physical geography has laid such a broad foundation for 
researches of this kind. Then we may learn with more precision, how far the 
species described from isolated specimens are founded in nature, or how far they 
may be only a particular stage of growth of other species; then we shall know, 
what is yet too little noticed, how extensive the range of variations is among ani- 
mals, observed in their wild state, or rather how much individuality there is in each 
and all living beings. So marked, indeed, is this individuality in many families,-and 
that of Turtles affords a striking example of this kind, - that correct descriptions of 
species can hardly be drawn from isolated specimens, as is constantly attempted to 
be done. I have seen hundreds of specimens of some of our Chelonians, among 
which there were not two identical. And truly, the limits of this variability con- 
stitutes one of the most important characters of many species; and without precise 
information upon this point for every genus, it will never be possible to have a 
solid basis for the distinction of species. Some of the most perplexing questions 
in Zoology and Palaeontology might long ago have been settled, had we had more 
precise information upon this point, and were it better known how unequal in this 
respect different groups of the animal kingdom are, when compared with one 
another. While the individuals of some species seem all different, and might be 
described as different species, if seen isolated or obtained from different regions, those 
of other species appear all as cast in one and the same mould. It must be, there- 
fore, at once obvious, how different the results of the comparison of one fauna with 
another may be, if the species of one have been studied accurately for a long 
period by resident naturalists, and the other is known only from specimens collected 
by chance travellers; or, if the fossil representatives of one period are compared 
with living animals, without both faunae having first been revised according to the 
same standard.1 
Another deficiency, in most works relating to the habits of animals, consists in 
the absence of general views and of comparisons. We do not learn from them, 
how far animals related by their structure are similar in their habits, and how far 
1 In this respect, I would remark that most of 
the cases, in which specific identity has been affirmed 
between living and fossil species, or between the 
fossils of different geological periods, belong to 
families which present either great similarity or 
extraordinary variability, and in which the limits of 
species are, therefore, very difficult to establish. 
Such cases should be altogether rejected in the 
investigation of general questions, involving funda- 
mental principles, as are untrustworthy observations 
always in other departments of science. Compare 
further, my paper upon the primitive diversity and 
number of animals, quoted above, in which this 
point is specially considered. Chap. I. 
HABITS OF ANIMALS. 
59 
these habits are the expression of their structure. Every species is described as if 
it stood alone in the world; its peculiarities are mostly exaggerated, as if to con- 
trast more forcibly with all others. Yet, how interesting would be a comparative 
study of the mode of life of closely allied species; how instructive a picture might 
be drawn of the resemblance there is in this respect between species of the same 
genus and of the same family. The more I learn upon this subject, the more am I 
struck with the similarity in the very movements, the general habits, and even in 
the intonation of the voices of animals belonging to the same family; that is to say, 
between animals agreeing in the main in form, size, structure, and mode of develop- 
ment. A minute study of these habits, of these movements, of the voice of animals 
cannot fail, therefore, to throw additional light upon their natural affinities. 
While I thus acknowledge the great importance of such investigations with refer- 
ence to the systematic arrangement of animals, I cannot help regretting deeply, that 
they are not more highly valued with reference to the information they might 
secure respecting the animals themselves, independently of any system. How much 
is there not left to study with respect to every species, after it is named and classi- 
fied. No one can read Nauman's Natural History of the German Birds without 
feeling that natural history would be much further advanced, if the habits of all 
other animals had been as accurately investigated and as minutely recorded; and yet 
that work contains hardly any thing of importance with reference to the systematic 
arrangement of birds. We scarcely possess the most elementary information neces- 
sary to discuss upon a scientific basis the question of the instincts and in general 
the faculties of animals, and to compare them together and with those of man,1 
not only because so few animals have been thoroughly investigated, but because so 
much fewer still have been watched during their earlier periods of life, when their 
faculties are first developing; and yet how attractive and instructive this growing 
age is in every living being! Who could, for instance, believe for a moment longer 
that the habits of animals are in any degree determined by the circumstances under 
which they live, after having seen a little Turtle of the genus Chelydra, still 
enclosed in its egg-shell, which it hardly fills half-way, with a yolk bag as large as 
itself hanging from its lower surface and enveloped in its amnios and in its allantois, 
with the eyes shut, snapping as fiercely as if it could bite without killing itself?2 
Who can watch the Sunfish (Pornotis vulgaris) hovering over its eggs and protecting 
them for weeks, or the Catfish (Pimelodus Catus) move about with its young, like 
1 Scheitlin, (P.,) Versuch einer vollstiindigen 
Thierseelenkunde, Stuttgart und Tubingen, 1840, 
2 vols. 8vo. - Cuvier, (Fred.,) Resume analyt- 
ique des observations sur 1'instinct et 1'intelligence 
des animaux, par R. Flourens, Ann. Sc. Nat., 2de 
ser., vol. 12. 
2 See, Part III., which is devoted to the Em- 
bryology of our Turtles. 60 
ESSAY ON CLASSIFICATION. 
Part I. 
a hen with her brood, without remaining satisfied that the feeling which prompts 
them in these acts is of the same kind as that which attaches the Cow to her 
suckling, or the child to its mother? Who is the investigator, who having once 
recognized such a similarity between certain faculties of Man and those of the higher 
animals can feel prepared, in the present stage of our knowledge, to trace the limit 
where this community of nature ceases ? And yet to ascertain the character of all 
these faculties there is but one road, the study of the habits of animals, and a 
comparison between them and the earlier stages of development of Man. I confess 
I could not say in what the mental faculties of a child differ from those of a 
young Chimpanzee. 
Now that we have physical maps of almost every part of the globe,1 exhibiting 
the average temperature of the whole year and of every season upon land and sea; 
now that the average elevation of the continents above the sea, and that of the 
most characteristic parts of their surface, their valleys, their plains, their table-lands, 
their mountain systems, are satisfactorily known; now that the distribution of moisture 
in the atmosphere, the limits of the river systems, the prevailing direction of the 
winds, the course of the currents of the ocean, are not only investigated, but mapped 
down, even in school atlases; now that the geological structure of nearly all parts 
of the globe has been determined with tolerable precision, zoologists have the widest 
field and the most accurate basis to ascertain all the relations which exist between 
animals and the world in which they live. 
Having thus considered the physical agents with reference to the share they may 
have had in calling organized beings into existence, and satisfied ourselves that 
they are not the cause of their origin, it now remains for us to examine more 
particularly these relations, as an established fact, as conditions in which animals and 
plants are placed at the time of their creation, within definite limits of action and 
reaction between them; for though not produced by the influence of the physical 
world, organized beings live in it, they are born in it, they grow up in it, they 
multiply in it, they assimilate it to themselves or feed upon it, they have even a 
modifying influence upon it within the same limits, as the physical world is sub- 
servient to every manifestation of their life. It cannot fail, therefore, to be highly 
interesting and instructive to trace these connections, even without any reference 
to the manner in which they were established, and this is the proper sphere of 
investigation in the study of the habits of animals. The behavior of each kind 
towards its fellow-beings, and with reference to the conditions of existence in which 
it is placed, constitutes a field of inquiry of the deepest interest, as extensive as it is 
1 Berghaus, Physikalischer Atlas, Gotha, 1838 
et seq., fol. - Johnston, (Alex. Keith,) Physical 
Atlas of Natural Phenomena, Edinburgh, 1848, 
1 vol. fol. Chap. I. 
HABITS OF ANIMALS. 
61 
complicated. When properly investigated, especially within the sphere which con- 
stitutes more particularly the essential characteristics of each species of animals and 
plants, it is likely to afford the most direct evidence of the unexpected independence 
of physical influences of organized beings, if I mistake not the evidence I have 
myself been able to collect. What can there be more characteristic of different 
species of animals than their motions, their plays, their affections, their sexual rela- 
tions, their care of their young, the dependence of these upon their parents, their 
instincts, etc., etc.; and yet there is nothing in all this which depends in the slight- 
est degree upon the nature or the influence of the physical conditions in which 
they live. Even their organic functions are independent of these conditions to a 
degree unsuspected, though this is the sphere of their existence which exhibits the 
closest connections with the world around. 
Functions have so long been considered as the test of the character of organs, 
that it has almost become an axiom in comparative anatomy and physiology, that 
identical functions presuppose identical organs. Most of our general works upon 
comparative anatomy are divided into chapters according to this view. And yet 
there never was a more incorrect principle, leading to more injurious consequences, 
more generally adopted. That naturalists should not long ago have repudiated it, 
is the more surprising as every one must have felt again and again how unsound 
it is. The organs of respiration and circulation of fishes afford a striking example. 
How long have not their gills been considered as the equivalent of the lungs of 
the higher Vertebrata, merely because they are breathing organs; and yet these gills 
are formed in a very different way from the lungs; they bear very different rela- 
tions to the vascular system; and it is now known that they may exist simultane- 
ously with lungs, as in some full-grown Batrachians, and, in the earlier embryonic 
stages of development, in all Vertebrata. There can no longer be any doubt now, 
that they are essentially different organs, and that their functions afford no test of 
their nature and cannot constitute an argument in favor of their organic identity. 
The same may be said of the vascular system of the fishes. Cuvier1 described their 
heart as representing the right auricle and the right ventricle, because it propels 
the blood it contains to the gills, in the same manner as the right ventricle pro- 
pels the blood to the lungs of the warm blooded animals; yet embryology has 
taught us that such a comparison based upon the special relations of the heart of 
fishes, is unjustifiable. The air sacs of certain spiders have also been considered 
as lungs, because they perform similar respiratory functions, and yet they are only 
modified tracheae,2 which are constructed upon such a peculiar plan, and stand in 
1 Cuvier, (G.,) Regn. Anim., 2de edit., vol. 2, 
p. 122. 
2 Leuckardt, (R.,) Ueber den Bau und die 
Bedeutung der sogenannten Lungen bei den Arach- 62 
ESSAY ON CLASSIFICATION. 
Part I. 
such different relations to the peculiar kind of blood of the Articulata,1 that no 
homology can be traced between them and the lungs of Vertebrata, no more 
than between the so-called lungs of the air breathing Mollusks, whose aerial respira- 
tory cavity is only a modification of the peculiar kind of gills observed in other 
Mollusks. Examples might easily be multiplied; I will, however, only allude further 
to the alimentary canal of Insects and Crustacea, with its glandular appendages, 
formed in such a different way from that of Vertebrata, or Mollusks, or Radiata, to 
their legs and wings, etc., etc. I might allude also to what has been called the foot 
in Mollusks, did it not appear like pretending to suppose that any one entertains 
still an idea that such a name implies any similarity between their locomotive 
apparatus and that of Vertebrata or Articulata, and yet, the very use of such a 
name misleads the student, and even some of the coryphees of our science have 
not freed themselves of such and similar extravagant comparisons, especially with 
reference to the solid parts of the frame of the lower animals.2 
The identification of functions and organs was a natural consequence of the 
prevailing ideas respecting the influence physical agents were supposed to have upon 
organized beings. But as soon as it is understood, how different the organs may 
be, which in animals perform the same function, organization is at once brought into 
such a position to physical agents as makes it utterly impossible to maintain any 
genetic connection between them. A fish, a crab, a mussel, living in the same 
waters, breathing at the same source, should have the same respiratory organs, if the 
elements in which these animals live had any thing to do with shaping their organi- 
zation. I suppose no one can be so short-sighted, as to assume that the same 
physical agents acting upon animals of different types, must produce, in each, peculiar 
organs, and not to perceive that such an assumption implies the very existence of 
these animals, independently of the physical agents. But this mistake recurs so 
constantly in discussions upon this and similar topics, that, trivial as it is, it requires 
to be rebuked.3 On the contrary, when acknowledging an intellectual conception, 
niden, in Siebold und Kolliker's Zeitschrift, f. 
wiss. Zool., 1849, L, p. 24G. 
1 Blanchard, (Em.,) De la circulation dans les 
Insectes, Compt. Rend., 1847, vol. 24, p. 870.- 
Agassiz, (L.,) On the Circulation of the Fluids in 
Insects, Proc. Amer. Asso., for 1849, p. 140. 
2 Carus, (C. G.,) Von den Ur-Theilen des 
Knochen- und Schalengeriistes, Leipzig, 1828, 1 vol., 
fol., p. Gl-89. 
8 I hope the day is not far distant, when zoolo- 
gists and botanists will equally disclaim having 
shared in the physical doctrines more or less pre- 
vailing now, respecting the origin and existence of 
organized beings. Should the time come when my 
present efforts may appear like fighting against 
windmills, I shall not regret having spent so much 
labor in urging my fellow-laborers in a right direc- 
tion ; but at the same time, I must protest now 
and for ever, against the bigotry spreading in some 
quarters, which would press upon science, doctrines 
not immediately flowing from scientific premises, 
and check its free progress. Chap. I. 
RELATIONS OF INDIVIDUALS. 
63 
as the preliminary step in the existence not only of all organized beings, but of 
every thing in nature, how natural to find that while diversity is introduced in the 
plan, in the complication and the details of structure of animals, their relations to 
the surrounding media are equally diversified, and consequently the same functions 
may be performed by the most different apparatus! 
SECTION XVII. 
RELATIONS OF INDIVIDUALS TO ONE ANOTHER. 
The relations in which individuals of the same species of animals stand to one 
another are not less determined and fixed than the relations of species to the sur- 
rounding elements, which we have thus far considered. The relations which individ- 
ual animals bear to one another are of such a character, that they ought long ago 
to have been considered as proof sufficient that no organized being could ever have 
been called into existence by another agency than the direct intervention of a 
reflective mind. It is in a measure conceivable that physical agents might pro- 
duce something like the body of the lowest kinds of animals or plants, and that 
under identical circumstances the same thing may have been produced again and 
again, by the repetition of the same process; but that upon closer analysis of the 
possibilities of the case, it should not have at once appeared how incongruous the 
further supposition is, that such agencies could delegate the power of reproducing 
what they had just called into existence, to those very beings, with such limitations, 
that they could never reproduce any thing but themselves, I am at a loss to under- 
stand. It will no more do to suppose that from simpler structures such a pro- 
cess may end in the production of the most perfect, as every step implies an 
addition of possibilities not even included in the original case. Such a delegation of 
power can only be an act of intelligence; while between the production of an 
indefinite number of organized beings, as the result of a physical law, and the repro- 
duction of these same organized beings by themselves, there is no necessary connec- 
tion. The successive generations of any animal or plant cannot stand, as far as 
their origin is concerned, in any causal relation to physical agents, if these agents 
have not the power of delegating their own action to the full extent to which they 
have already been productive in the first appearance of these beings; for it is a 
physical law that the resultant is equal to the forces applied. If any new being 
has ever been produced by such agencies, how could the successive generations 
enter, at the time of their birth, into the same relations to these agents, as their 64 
ESSAY ON CLASSIFICATION. 
Part I. 
ancestors, if these beings had not in themselves the faculty of sustaining their char- 
acter, in spite of these agents ? Why, again, should animals and plants at once begin 
to decompose under the very influence of all those agents which have been subservi- 
ent to the maintenance of their life, as soon as life ceases, if life is limited or deter- 
mined by them? 
There exist between individuals of the same species relations far more complicated 
than those already alluded to, which go still further to disprove any possibility of 
causal dependence of organized beings upon physical agents. The relations upon 
which the maintenance of species is based, throughout the animal kingdom, in the 
universal antagonism of sex, and the infinite diversity of these connections in differ- 
ent types, have really nothing to do with external conditions of existence; they 
indicate only relations of individuals to individuals, beyond their connections with the 
material world in which they live, flow, then, could these relations be the result of 
physical causes, when physical agents are known to have a specific sphere of action, 
in no way bearing upon this sphere of phenomena ? 
For the most part, the relations of individuals to individuals are unquestionably 
of an organic nature, and, as such have to be viewed in the same light as any other 
structural feature; but there is much, also, in these connections that partakes of a 
psychological character, taking this expression in the widest sense of the word. 
When animals fight with one another, when they associate for a common purpose, 
when they warn one another in danger, when they come to the rescue of one 
another, when they display pain or joy, they manifest impulses of the same kind as 
are considered among the moral attributes of man. The range of their passions is 
even as extensive as that of the human mind, and I am at a loss to perceive a 
difference of .kind between them, however much they may differ in degree and in 
the manner in which they are expressed. The gradations of the moral faculties 
among the higher animals and man are, moreover, so imperceptible, that to deny to 
the first a certain sense of responsibility and consciousness, would certainly be an 
exaggeration of the difference between animals and man. There exists, besides, as 
much individuality, within their respective capabilities, among animals as among men, 
as every sportsman, or every keeper of menageries, or every farmer and shepherd 
can testify who has had a large experience with wild, or tamed, or domesticated 
animals.1 
This argues strongly in favor of the existence in every animal of an immaterial 
1 See J. E. Ridinger's various works illustra- 
tive of Game Animals, which have appeared under 
different titles, in Augsburg, from 1729 to 1778.- 
Geoffroy St. Hilaire, et Cuvier, (Fr.,) Histoire 
naturelle des Mammiferes, Paris, 1820-35, 3 vols. 
fol.-Lenz, (IL 0.,) Gemeinniitzige Naturgeschichte, 
Gotha, 1835, 4 vols. 8vo. - Bingley, (W.,) Animal 
Biography, London, 1803, 3 vols. 8vo. Chap. I. 
RELATIONS OF INDIVIDUALS. 
65 
principle similar to that which, by its excellence and superior endowments, places 
man so much above animals.1 Yet the principle exists unquestionably, and whether 
1 It might easily be shown that the exaggerated 
views generally entertained of the difference exist- 
ing between man and monkeys, are traceable to the 
ignorance of the ancients, and especially the Greeks, 
to whom we owe chiefly our intellectual culture, of 
the existence of the Orang-Outang and the Chim- 
panzee. The animals most closely allied to man 
known to them were the Red Monkey, x^og, the 
Baboon, xvroz/qaZo^, and the Barbary Ape, ni&i]xog. 
A modern translation of Aristotle, it is true, makes 
him say that monkeys form the transition between 
man and quadrupeds; (Aristoteles, Naturge- 
schichte der Thiere, von Dr. F. Strack, Frankfurt- 
am-Main, 1816, p. 65;) but the original says no 
such thing. In the History of Animals, Book 2, 
Chap. V., we read only, ma 8s row ^cocov snapcpo- 
T^V (fJVGIV TW TS av^pwrttp Xai TOig TET^dnoOlP. 
There is a wide difference between " partaking of 
the nature of both man and the quadrupeds," and 
" forming a transition between man and the quadru- 
peds." The -whole chapter goes on enumerating the 
structural similarity of the three monkeys named 
above with man, but the idea of a close affinity is 
not even expressed, and still less that of a transi- 
tion between man and the quadrupeds. The writer, 
on the contrary, dwells very fully upon the marked 
differences they exhibit, and knows as well as any 
modern anatomist has ever known, that monkeys have 
four hands. 8s xai ^Qa^iovag, Martin avOoconog, 
. . . . iSiovg 8s roi>g noSag. eici yao oiov ^EiQEg 
[isyaXai. Kai oi SaxvvXoi wgnsq oi w 6 psyag 
(zaxQoraTog • xai to narco rov noSog ^eiqi ouoiov, nkrtv 
tm to [Mjxog to ri^g XEi^og tm ra so^ara teivov na&d- 
nEQ fisvaQ. Tovto 8s etc dn^ov GnfyooTsoov, xaxwg 
xai d[iv8(jcog fiiuovusrov ms'^v. 
It is strange that these clear and precise dis- 
tinctions should have been so entirely forgotten in 
the days of Linnaeus that the great reformer in 
Natural History had to confess, in the year 1746, 
that he knew no character by which to distinguish 
man from the monkeys. Fauna Suecica, Praefat. p. 2. 
" Nullum characterem adhuc eruere potui, unde 
homo a simia internoscatur." But it is not upon 
structural similarity or difference alone that the re- 
lations between man and animals have to be con- 
sidered. The psychological history of animals shows 
that as man is related to animals by the plan of his 
structure, so are these related to him by the char- 
acter of those very faculties which are so tran- 
scendent in man as to point at first to the necessity 
of disclaiming for him completely any relationship 
with the animal kingdom. Yet the natural history 
of animals is by no means completed after the so- 
matic side of their nature has been thoroughly in- 
vestigated ; they, too, have a psychological individ- 
uality, which, though less fully studied, is neverthe- 
less the connecting link between them and man. I 
cannot, therefore, agree with those authors who would 
disconnect mankind from the animal kingdom, and 
establish a distinct kingdom for man alone, as 
Ehrenberg (Das Naturreich des Menschen, Berlin, 
1835, fol.) and lately I. Geoffroy St. Hilaire, (Hist, 
nat. generale, Paris, 1856, Tome 1, Part 2, p. 167,) 
have done. Compare, also, Chap. II., where it is 
shown for every kind of groups of the animal kingdom 
that the amount of their difference one from the 
other never affords a sufficient ground for removing 
any of them into another category. A close study 
of the dog might satisfy every one of the similarity 
of his impulses with those of man, and those im- 
pulses are regulated in a manner which discloses 
psychical faculties in every respect of the same kind 
as those of man; moreover, he expresses by his 
voice his emotions and his feelings, with a precision 
which may be as intelligible to man as the articu- 
lated speech of his fellow men. His memory is so 
retentive that it frequently baffles that of man. And 
though all these faculties do not make a philosopher 
of him, they certainly place him in that respect 
upon a level with a considerable proportion of poor 
humanity. The intelligibility of the voice of ani- 
mals to one another, and all their actions connected 
with such calls are also a strong argument of their 
perceptive power, and of their ability to act spon- 66 
ESSAY ON CLASSIFICATION. 
Part I. 
it be called soul, reason, or instinct, it presents in the whole range of organized 
beings a series of phenomena closely linked together; and upon it are based not 
only the higher manifestations of the mind, but the very permanence of the specific 
differences which characterize every organism. Most of the arguments of philosophy 
in favor of the immortality of man apply equally to the permanency of this principle 
in other living beings. May I not add, that a future life, in which man should be 
deprived of that great source of enjoyment and intellectual and moral improvement 
which result from the contemplation of the harmonies of an organic world, would 
involve a lamentable loss, and may we not look to a spiritual concert of the com- 
bined worlds and all their inhabitants in presence of their Creator as the highest 
conception of paradise ? 
SECTION XVIII. 
METAMORPHOSES OF ANIMALS. 
The study of embryology is of very recent date; the naturalists of the past 
century, instead of investigating the phenomena accompanying the first formation and 
growth of animals, were satisfied with vague theories upon reproduction.1 It is true 
taneously and with logical sequence in accordance 
with these perceptions. There is a vast field open 
for investigation in the relations between the voice 
and the actions of animals, and a still more inter- 
esting subject of inquiry in the relationship between 
the cycle of intonations which ditferent species of 
animals of the same family are capable of uttering, 
which, as far as I have as yet been able to trace 
them, stand to one another in the same relations as 
the different, so-called, families of languages (Schle- 
gel, (Fr.,) Ueber die Sprache und Weisheit der 
Indier, Heidelberg, 1808, 1 vol. 8vo.- Humboldt, 
(W. v.,) Ueber die Kawi-Sprache, auf der Insel 
Java, Berlin, 1836-39, 3 vols. 4to. Abh. Ak. d. Wis- 
sensch. - Steinthal, (H.,) Grammatik, Logik und 
Psychologic, Berlin, 1855, 1 vol. 8vo.) in the human 
family. All the Canina bark ; the howling of the 
wolves, the barking of the dogs and foxes, are 
only different modes of barking, comparable to one 
another in the same relation as the monosyllabic, 
the agglutinating, and the inflecting languages. The 
Felidae mew : the roaring of the lion is only ano- 
ther form of the mewing of our cats and the other 
species of the family. The Equina neigh or bray: 
the horse, the donkey, the zebra, the dow, do not differ 
much in the scale of their sounds. Our cattle, and the 
different kinds of wild bulls, have a similar affinity 
in their intonations; their lowing differs not in kind, 
but only in the mode of utterance. Among birds, 
this is, perhaps, still more striking. Who does not 
distinguish the note of any and every thrush, or of 
the warblers, the ducks, the fowls, etc., however nu- 
merous their species may be, and who can fail to 
perceive the affinity of their voices ? And does 
this not indicate a similarity also in their mental 
faculties? 
1 Buffon, (G. L. LeClerc de,) Discours sur 
la nature des Animaux, Geneve, 1754, 12mo.; also 
in his Oeuvres completes, Paris, 1774-1804, 3G vols. 
4to. Chap. I. 
METAMORPHOSES OF ANIMALS. 
67 
the metamorphoses of Insects became very early the subject of most remarkable 
observations,1 but so little was it then known that all animals undergo great changes 
from the first to the last stages of their growth, that metamorphosis was considered 
a distinguishing character of Insects. The differences between Insects, in that 
respect, are however already so great, that a distinction was introduced between 
those which undergo a complete metamorphosis, that is to say, which appear in 
three successive different forms, as larvae, pupae, and perfect insects, and those with 
an incomplete metamorphosis, or whose larvae differ little from the perfect insect. 
The range of these changes is yet so limited in some insects, that it is not only 
not greater, but is even much smaller than in many representatives of other classes. 
We may, therefore, well apply the term metamorphosis to designate all the changes 
which animals undergo, in direct and immediate succession,2 during their growth, 
whether these changes are great or small, provided they are correctly qualified for 
each type. 
The study of embryology, at first limited to the investigation of the changes 
which the chicken undergoes in the egg, has gradually extended to every type 
of the animal kingdom; and so diligent and thorough has been the study, that 
the first author who ventured upon an extensive illustration of the whole field, 
C. E. von Baer, has already presented the subject in such a clear manner, and 
drawn general conclusions so accurate and so comprehensive, that all subsequent 
researches in this department of our science, may be considered only as a further 
development of the facts first noticed by him and of the results he has already 
deduced from them.3 It was he who laid the foundation for the most extensive 
1 Swammerdam, (J.,) Biblia Naturae, sive His- 
toria Insectorum, etc., Lugduni-Batavorum, 1737-38, 
3 vols. fol. fig.- Reaumur, (R. Ant. de,) Memoires 
pour servir a 1'Histoire des Insectes, Paris, 1734-42, 
C vol. 4to. fig. - Roesel von Rosenhof, (A. J.,) 
Insectenbelustigungen, Nurnberg, 1746-61, 4 vols. 
4to. fig. 
2 I say purposely, " in direct and immediate suc- 
cession," as the phenomena of alternate generation 
are not included in metamorphosis, and consist chiefly 
in the production of new germs, which have their 
own metamorphosis; while metamorphosis proper 
relates only to the successive changes of one and 
the same germ. 
8 Without referring to the works of older writers, 
such as De Graaf, Malpighi, Haller, Wolf, Meckel, 
Tiedemann, etc., which are all enumerated with many 
others in Bischoff's article " Entwickelungsges- 
chichte," in Wagner's Handworterbuch der Physio- 
logie, vol. 1, p. 8GO, I shall mention hereafter, chiefly 
those published since, under the influence of Dollin- 
ger, this branch of science has assumed a new char- 
acter:- Baer, (C. E. v.,) Heber Entwickelungs- 
geschichte der Thiere, Kbnigsberg, 1828-37, 2 vols. 
4to. fig. The most important work yet published. 
The preface is a model of candor and truthfulness, 
and sets the merits of Dollinger in a true and beauti- 
ful light. As text-books, I would quote, Burdacii, 
(C. F.,) Die Physiologic als Erfahrungswissenschaft, 
Leipzig, 1829-40, 6 vols. 8vo.; French, Paris, 
1837-41, 9 vols. 8vo. - Muller, (J.,) Handbuch der 
Physiologic des Menschen, Coblenz, 1843, 2 vols. 8vo. 
4th edit.; Engl, by W. Baly, London, 1837, 8vo. 
- Wagner, (R.,) Lehrbuch der Physiologic, Leip- 68 
ESSAY ON CLASSIFICATION. 
Part I. 
generalizations respecting the mode of formation of animals; for he first discovered, 
in 1827, the ovarian egg of Mammalia, and thus showed for the first time, that 
there is no essential difference in the mode of reproduction of the so-called vivip- 
arous and oviparous animals, and that man himself is developed in the same manner 
as the animals. The universal presence of eggs in all animals and the unity of their 
structure, which was soon afterwards fully ascertained, constitute, in my opinion, the 
greatest discovery of modern times in the natural sciences.1 
It was, indeed, a gigantic step to demonstrate such an identity in the material 
basis of the development of all animals, when their anatomical structure was already 
known to exhibit such radically different plans in their full-grown state. From that 
time a more and more extensive investigation of the manner in which the first 
germ is formed in these eggs, and the embryo develops itself; how its organs 
grow gradually out of a homogeneous mass; what changes, what complications, what 
connections, what functions they exhibit at every stage; how in the end the young 
animal assumes its final form and structure, and becomes a new, independent being, 
could not fail to be the most interesting subject of inquiry. To ascertain all this, 
in as many animals as possible, belonging to the most different types of the animal 
kingdom, became soon the principal aim of all embryological investigations; and it 
can truly be said, that few sciences have advanced with such astonishing rapidity, 
and led to more satisfactory results. 
For the actual phases of the mode of development of the different types of the 
animal kingdom, I must refer to the special works upon this subject,2 no general 
zig, 1839-42, 2 vols. 8vo. - Valentin, (G.,) Hand- 
buch der Entwickelungsgeschichte, etc., Berlin, 1835, 
1 vol. 8vo. - Lehrbuch der Physiologic des Men- 
schen, Braunschweig, 1843, 2 vols. 8vo. - Longet, 
(F. A.,) Traits de Physiologic, Paris, 1850, 2 vols. 
8vo. - Kolliker, (Alb.,) Microscopische Anatomic 
des Menschen, Leipzig, 1840-54, 2 vols. 8vo. fig.- 
See also Owen's Lectures, etc., Siebold und Stan- 
nius's Lehrbuch, and Carus's Morphologic, q. a. 
p. 27, and p. 18. I might further quote almost every 
modern text-book on physiology, but most of them 
are so evidently mere compilations, exhibiting no 
acquaintance with the subject, that I omit purposely 
to mention any other elementary works. 
1 Baer, (C. E. a,) De Ovi Mammalium et 
Hominis Genesi, Kbnigsberg, 1827, 4to., fig. - 
Purkinje, (J. E.) Symbol® ad ovi avium historian! 
ante incubationem, Lipsi®, 1830, 4to. fig. - Wag- 
ner, (R.,) Prodromus Histori® generationis Hominis 
atque Animalium, etc., Lipsi®, 183G, 1 vol., fol., fig. 
- leones physiologic®, Lipsiae, 1839, 4to. fig. 
2 The limited attention, thus far paid in this 
country to the study of Embryology, has induced 
me to enumerate more fully the works relating to 
this branch of science, than any others, in the hope 
of stimulating investigations in that direction. There 
exist upon this continent a number of types of ani- 
mals, the embryological illustration of which would 
add immensely to the stock of our science; such 
are the Opossum, the Ichthyoid Batrachians, the 
Lepidosteus, the Amia, etc., not to speak of the 
opportunities which thousands of miles of sea-coast, 
everywhere easily accessible, afford for embryologi- 
cal investigations, from the borders of the Arctics 
to the Tropics. In connection with Embryology 
the question of Individuality comes up naturally. Chap. I. 
METAMORPHOSES OF ANIMALS. 
69 
treatise embracing the most recent investigations having as yet been published; and 
I must take it for granted, that before forming a definite opinion upon the com- 
parisons instituted hereafter between the growth of animals, and the structural grada- 
tion among full-grown animals, or the order of succession of the fossils characteristic 
of different geological periods, the necessary information respecting these changes has 
been gathered by my readers, and sufficiently mastered to enable them to deal with 
it freely. 
The embryology of Polypi has been very little studied thus far; what we know 
of the embryonic growth of these animals relates chiefly to the family of Actinoids.1 
When the young is hatched, it has the form of a little club-shaped or pear-shaped 
body, which soon assumes the appearance of the adult, from which it differs only by 
having few tentacles. The mode of ramification and the multiplication by buds 
have, however, been carefully and minutely studied in all the families of this class.2 
Acalephs present phenomena so peculiar, that they are discussed hereafter in a 
special section. Their young3 are either polyplike or resemble more immediately 
See upon this subject:-Leuckart, (Rud.,) Ueber 
den Polymorphismus der Individuen oder die 
Erscheinung der Arbeitstheilung in der Natur, 
Giessen, 1851, 4to.- Reichert, (C. B.,) Die mono- 
gene Fortpflanzung, Dorpat, 1852. - Huxley, (Th. 
II.,) Upon Animal Individuality, Ann. and Mag. 
Nat. Hist. 2d ser., 1852, vol. 9, p. 507. - Forbes, 
(Ed.,) On the supposed Analogy between the Life 
of an Individual and the Duration of a Species, Ann. 
and Mag. Nat. Hist., 2d ser., 1852, vol. 10, p. 59. 
- Braun, (Al.,) Das Individuum der Pflanze, q. a. 
- Betrachtungen uber die Erscheinung der Ver- 
jiingung in der Natur, Freiburg, 1849, 4to. fig. 
1 Sars, (M.,) Beskrivelser og Jagttagelser over 
nogle maerkelige eller nye i Havet ved den Ber- 
genske Kyst levende Dyr, etc., Bergen, 1835, 4to. 
- Fauna littoralis Norvegiae, Christiania, 1846, fob 
fig. - Rathke, (H.,) in Burdach's Physiologic, vol. 
2d, 2d edit. p. 215. - Zur Morphologic, Reisebemer- 
kungen aus Taurien, Riga und Leipzig, 1837, 4to., 
fig. - Agassiz, (L.,) Twelve Lectures, etc., p. 40, 
et seq. 
2 See Dana's Zoophytes, and Milne-Edwards 
et Haime, Recherches, etc., q. a. p. 31, note 2. 
3 Siebold, (C. Th. E. v.,) Beitrage zur Natur- 
geschichte der wirbellosen Thiere, Dantzig, 1839, 
4to. p. 29. - Loven, (S. L.) Beitrag zur Kenntniss 
der Gattungen Campanularia und Syncoryne, Wiegm. 
Arch., 1837, p. 249 and 321; French Ann. Sc. n. 
2de ser., vol. 15, p. 157. - Sars, (M.,) Beskrivelser, 
q. a. - Fauna littoralis, q. a. - Nordmann, (Al. v.,) 
Snr les changements que l'age apporte dans la 
maniere d'etre des Campanulaires, Comptes-Rendus, 
1834, p. 709.- Steenstrup, (J.,) Ueber den Gene- 
rations-Wechsel oder die Fortpflanzung und Ent- 
wickelung durch abwechselnde Generationen, Uebers, 
von Lorenzen, Kopenh. 1842, 8vo., fig.; Engl, 
by G. Busk, (Ray Society,) London, 1845, 8vo. - 
VanBeneden, (P. J.,) Memoire sur les Campanu- 
laires de la cote d'Ostende, etc., Mem. Ac. Brux. 
1843, vol. 17, 4to. fig. - Recherches sur 1'Embry- 
ogenie des Tubulaires, etc., Mem. Ac. Brux. 1844, 
4to. fig. - Dujardin, (Fel.,) Observations sur un 
nouveau genre de Medusaires (Cladonema,) pro- 
venant de la metamorphose des Syncorynes, Ann. Sc. 
n. 2de ser. 1843, vol. 20, p. 370. - Memoire sur le 
developpement des Medusaires et des Polypes 
Hydraires, Ann. Sc. n. 3e ser., 1845, vol. 4, p. 257. 
- Will, (J. G. Fr.,) Horie tergestime, Leipzig, 
1844, 4to. fig. - Frey, (H.,) und Leuckart, (R.,) 
Beitrage zur Kenntniss wirbelloser Thiere, Braun- 
schweig, 1847, 4to. fig.- Dalyell, (Sir J. G.,) Rare 70 
ESSAY ON CLASSIFICATION. 
Part I. 
the type of their class. Few multiply in a direct, progressive development. As to 
Echinoderms, they have for a long time almost entirely escaped the attention of 
Embryologists, but lately J. Muller has published a series of most important investi- 
gations upon this class,1 disclosing a wonderful diversity in the mode of their develop- 
and Remarkable Animals of Scotland, etc., London, 
1847, 2 vols. 4to. fig. - Forbes, (Ed.,) Monograph 
of the British Naked-eyed Medusae, London, 1847, 
1 vol. fol. fig. (Ray Society.) - On the Morphology 
of the Reproductive System of Sertularian Zoophytes, 
etc., Ann. and Mag. Nat. Hist., 1844, vol. 14, p. 385. 
- Agassiz, (L.,) Twelve Lectures, etc., q. a. - 
Des or, (Ed.,) Lettre sur la generation mddusipare 
des Polypes Hydraires, Ann. Sc. Nat., 3e ser., 1849, 
vol. 12, p. 204. - Krohn, (A.,) Bemerkungen fiber 
die Geschlechtsverhifltnisse der Sertularinen, Mul- 
ler's Arch., 1843, p. 174. - Ueber die Brut des 
Cladonema radiatum und deren Entwickelung zum 
Stauridium, Muller's Arch., 1853, p. 420. - Ueber 
Podocoryne carnea Sars und die Fortpflanzungsweise 
ihrer medusenartigen Sprosslinge, Wiegm. Arch., 
1851, I., p. 2G3. - Ueber einige niedere Thiere, 
Muller's Arch., 1853, p. 137.-Ueber die frfihesten 
Entwickelungsstufen der Pelagia noctiluca, Muller's 
Arch., 1855, p. 491. - Kolliker, (A.,) Die Schwimm- 
polypen, etc., q. a. - Busch, (W.,) Beobachtungen 
fiber Anatomie und Entwickelungsgeschichte einiger 
wirbelloser Seethiere, Berlin, 1851, 4to. fig. pp. 1, 
25 and 30. - Gegenbauer, Kolliker und Mul- 
ler, Bericht fiber einige im Herbste 1852 in Messina 
angestellte anatomische Untersuchungen, Zeitsch. f. 
wiss. Zook, vol. 4, p. 299.- Gegenbauer, (C.,) 
Ueber die Entwickelung von Doliolum, der Schei- 
benquallen und von Sagitta,. Zeitsch. f. wiss. Zool., 
1853, p. 13. - Beitrage zur niihern Kenntniss der 
Schwimmpolypen (Siphonophoren,) Zeitsch. f. wiss. 
Zool., 1853, vol. 5, p. 285. - Ueber Diphyes turgida, 
etc., Zeitsch. f. wiss. Zool., 1853, vol. 5, p. 442. - 
Ueber den Entwickclungscyclus von Doliolum, etc., 
Zeitsch. f. wiss. Zool., 1855, vol. 7, p. 283. - 
Frantzius, (Al. v.,) Ueber die Jungen der Cephea, 
Zeitsch. f. wiss. Zool., vol. 4, p. 118. - Muller, (J.,) 
Ueber cine eigenthiimliche Meduse des Mittelmeeres 
und ihren Jugendzustand, Muller's Arch., 1851, p. 272. 
- Schultze, (M..) Ueber die mannlichen Gesclile- 
chtstheile der Campanularia geniculata, Muller's 
Arch., 1850, p. 53. - Hincks, (Th.,) Notes on the 
Reproduction of the Campanulariadae, etc., Ann. and 
Mag. Nat. Hist., 2d ser., 1852, vol. 10, p. 81. - Fur- 
ther Notes on British Zoophytes, Ann. and Mag. Nat. 
Hist., 1853, vol. 15, p. 127. - Allman, (G. J.,) On 
Hydroids, Rep. Brit. Ass. Adv. Sc., 1852, p. 50.- 
Derbes, (A.,) Note sur les organes reproducteurs et 
1'embryogenie du Cyanea chrysaora, Ann. Sc. Nat., 
3e ser., 1850, vol. 13, p. 377. - Vogt, (C.,) Ueber 
die Siphonophoren, Zeitsch. f. wiss. Zool., 1852, 
vol. 3, p. 522. - Huxley, (Th. II.,) On the Anat- 
omy and Affinities of the Family of the Medusse, 
Philos. Trans. Roy. Soc., 1849, II., p. 413. - An 
Account of Researches into the Anatomy of the 
Hydrostatic Acalephm, Proc. Brit. Ass. Adv. Sc., 
1851, p. 78. - Leuckardt, (R.,) Zoologische Unter- 
suchungen, Giessen, 1853-54, 4to. fig. 1st Fasc.- 
Zur nahern Kenntniss der Siphonophoren von Nizza, 
Wiegm. Arch., 1854, p. 249. - Stimpson, (W.,) 
Synopsis of the Marine Invertebrata of Grand Manan, 
Smithson. Contrib., 1853, 4to. fig. - Leidy, (Jos.,) 
Contributions towards a Knowledge of the Marine 
Invertebrate Fauna, etc., Journ. Acad. Nat. Sc., 
Philad., 2d ser. 1855, vol. 3, 4to. fig. - See also 
below, Sect. 20. 
1 Beskrivelser, etc., p. 37. - Ueber die Ent- 
wickelung der Seesterne, Wiegm. Arch., 1844, I., 
p. 1G9, fig.- Fauna littoralis, etc., p. 47. - Muller, 
(J.,) Ueber die Larven u. die Metamorphose der 
Ophiuren u. Seeigel, Akad. d. Wiss., Berlin, 1848. - 
Ueber die Larven u. die Metamorphose der Echino- 
dermen, 2te Abh., Ak. d. Wiss., Berlin, 1849. - 
Ueber die Larven u. die Metamorphose der Holo- 
thurien u. Asterien, Ak. d. Wiss., Berlin, 1850.- 
Ueber die Larven u. die Metamorphose der Echino- 
dermen, 4te Abh., Ak. d. Wiss., Berlin, 1852.- 
Ueber die Ophiurenlarven des Adriatischen Meeres, Chap. I. 
METAMORPHOSES OF ANIMALS. 
71 
ment, not only in the different orders of the class, but even in different genera 
of the same family. The larvae of many have a close resemblance to diminutive 
Ctenophorae, and may be homologized with this type of Acalephs. 
As I shall hereafter refer frequently to the leading divisions of the animal king- 
dom, I ought to state here, that I do not adopt some of the changes which have 
been proposed lately in the limitation of the classes, and which seem to have been 
pretty generally received with favor. The undivided type of Radiata appears to 
me as one of the most natural branches of the animal kingdom, and I consider 
its subdivision into Coelenterata and Echinodermata, as an exaggeration of the ana- 
tomical differences observed between them. As far as the plan of their structure 
is concerned, they do not differ at all, and that structure is throughout homologi- 
cal. In this branch I recognize only three classes, Polypi, Acaleplice, and Echinoder- 
mata. The chief difference between the two first lies in the radiating partitions of 
the main cavity of the Polypi, supporting the reproductive organs; moreover, the 
digestive cavity in this class consists of an inward fold of the upper aperture of 
the common sac of the body, while in Acalephs there exist radiating tubes, at least 
in the proles medusina, which extend to the margin of the body where they anas- 
tomoze, and the digestive cavity is hollowed out of the gelatinous mass of the 
body. This is equally true of the Hydroids, the Medusae proper, and the Cteno- 
phorae; but nothing of the kind is observed among Polypi. Siphonophorae, whether 
their proles medusina becomes free or not, and Hydroids agree in having, in the proles 
medusina, simple radiating tubes, uniting into a single circular tube around the mar- 
gin of the bell-shaped disk. These two groups, constitute together, one natural 
order, in contradistinction from the Covered-eyed Medusae, whose radiating tubes 
ramify towards the margin and form a complicated net of anastomoses. Morpho- 
logically, the proles polypoidea of the Acalephs, is as completely an Acaleph, as their 
Ak. d. Wiss., Berlin, 1852. - Ueber den allge- 
meinen Plan in der Entwickelung der Echinodermen, 
Ak. d. Wiss., Berlin, 1853. - Ueber die Gattungen 
der Seeigellarven, 7te Abh., Ak. d. Wiss., 1855. - 
Ueber den Canal in den Eiern der Holothurien, 
Miiller's Arch., 1854, p. 60. - French abstracts of 
these papers may be found in Ann. Sc. Nat., 3e 
ser., 1852 and '53, vols. 17, 19, and 20; An English 
account is published by Huxley, (Th. H.,) Report 
upon the Researches of Prof. Muller into the Anat- 
omy and Development of the Echinoderms, Ann. and 
Mag. Nat. Hist., 2d ser., vol. 8, 1851, p. 1. - Koren 
und Danielssen in Nyt Magazin for Naturvid, vol. 5, 
p. 253, Christiania, 1847 ; Ann. Sc. Nat. 1847, p. 347. 
- Agassiz, (L.,) Twelve Lectures, etc., p. 13. - 
Derbes, (A.,) Sur la formation de 1'embryon chez 
1'oursin comestible, Ann. Sc. Nat., 3e ser., vol. 8, 
p. 80. - Bush, (W.,) Beobachtungen, etc., q. a. - 
Ueber die Larve der Comatula, Muller's Arch. 18-19, 
p. 400. - Krohn, (A.,) Ueber die Entwickelung der 
Seesterne und Holothurien, Muller's Arch., 1853, 
p. 317. - Ueber die Entwickelung einer lebendig 
gebiihrenden Ophiure, Muller's Arch., 1851, p. 338. 
- Ueber die Larve des Echinus brevispinosus, Mul- 
ler's Arch., 1853, p. 361. - Beobachtungen tiber 
Echinodermenlarven, Muller's Arch., 1854, p. 208.- 
Schultze, (M.,) Ueber die Entwickelung von Ophio- 
lepis squamata, Muller's Arch., 1852, p. 37. 72 
ESSAY ON CLASSIFICATION. 
Part I. 
proles medusina^ and whether they separate or remain connected, their structural 
relations are everywhere the same. A comparison of Hydractinia, which is the 
most common and the most polymorphous Hydroid, with our common Portuguese 
Man-of-War (Physalia,) may at once show the homology of their most polymorphous 
individuals. 
The embryology of Mollusks has been very extensively investigated, and some 
types of this branch are among the very best known in the animal kingdom. The 
natural limits of the branch itself appear, however, somewhat doubtful. I hold that 
it must include the Bryozoa,2 which lead gradually through the Brachiopods3 and 
Tunicata to the ordinary Acephala, and I would add, that I have satisfied myself 
of the propriety of uniting the Vorticellidaa with Bryozoa. On the other hand, the 
Cephalopods can never be separated from the Mollusks proper, as a distinct branch ; 
the partial segmentation of their yolk no more affords a ground for their separation, 
than the total segmentation of the yolk of Mammalia would justify their separation 
from the other Vertebrata. Moreover, Cephalopods are in all the details of their 
structure homologous with the other Mollusks. The Tunicata are particularly inter- 
esting, inasmuch as the simple Ascidians have pedunculated young, which exhibit the 
most striking resemblance to Bol tenia, and form, at the same time, a connecting link 
with the compound Ascidians.4 The development of the Lamellibranchiata seems to 
1 I shall show this fully in my second volume. 
Meanwhile, see my paper on the structure and 
homologies of Radiata, q. a., p. 20. 
2 Allman, (G. J.,) On the Present State of our 
Knowledge of the Fresh Water Polyzoa, Proc. Brit. 
Asso. Adv. Sc., 20th Meet., Edinburgh, 1850, p- 305. 
- Proc. Irish Ac. 1850, vol. 4, p. 470. - Ibid., 1853, 
vol. 5, p. 11. - VanBeneden, (P. J.,) Recherches 
sur l'Anatomie, la physiologic et le developpement 
des Bryozoaires qui habitent la cote d'Ostende, Nouv. 
Mem. Ac. Brux., 1845, vol. 18.- Dumortier, (B. C.,) 
et VanBeneden, (P. J.,) Histoire naturelie des 
Polypes composes d'eau douce, Mem. Ac. Brux., 
1850, vol. 16, 4to. fig. - Hincks, (Th.,) Notes on 
British Zoophites, with Descriptions of some New 
Species, Ann. and Mag. Nat. Hist., 2d ser., 1851, 
vol. 8, p. 353. - Ehrenberg, (C. G.,) Die Infu- 
sionsthiere als vollkommene Organismen, Leipzig, 
1838, 2 vols. fol. fig.- Stein, (F.,) Infusionsthiere 
auf ihre Entwickelungsgeschichte untersucht, Leip- 
zig, 1854, 1 vol. 4to. fig. - Frantzius, (Al. v.,) 
Analecta ad Ophrydii versatilis historiam naturalem, 
Vratislav, 1849. - Lachmann, (C. F. J.,) Ueber die 
Organization der Infusorien, besonders der Vorticel- 
len, Muller's Arch., 1856, p. 340. Having satisfied 
myself that the Vorticellidas are Bryozoa, I would 
also refer here to all the works on Infusoria in which 
these animals are considered. 
8 I see from a short remark of Leuckart, Zeitsch. 
f. wiss. Zool., vol. 7, suppl., p. 115, that he has also 
perceived the close relationship which exists between 
Brachiopods and Bryozoa. 
4 Savigny, (J. C.,) Memoires sur les Anim. sans 
Vertebres, etc. q. a. - Chamisso, (Ad. a.,) De 
animalibus quibusdam e classe Vermium Linnaeana, 
Fasc. 1, De Salpa, Berol, 1819, 4to., fig. - Meyen, 
(F. J.,) Beitrage zur Zoologie, etc., 1st Abth., uber 
Salpen, Nov. Act. Nat. Cur. 1832, vol. 16.- 
Edwards, (II. Milne,) Observations sur les Asci- 
dies composees des cotes de la Manche, Paris, 1841, 
4to., fig. - Sars, (M.,) Beskrivelser, q. a. - Fauna 
lift., q. a. - VanBeneden, (P. J.,) Recherches sur Chap. I. 
METAMORPHOSES OF ANIMALS. 
73 
be very uniform, but they differ greatly as to their breeding, many laying their 
eggs before the germ is formed, whilst others carry them in their gills until the 
young are entirely formed.1 This is observed particularly among the Unios, some of 
which, however, lay their eggs very early, while others carry them for a longer 
or shorter time, in a special pouch of the outer gill, which presents the most diversi- 
fied forms in different genera of this family. Nothing is as yet known of the 
development of Brachiopods. The Gasteropods2 exhibit a much greater diversity 
1'embryogenie, l'anatomie et la physiologic des Asci- 
dies simples, Mem. Ac. Brux., 1847, vol. 20. - 
Krohx, (A.,) Ueber die Entwickelung der Ascidien, 
Muller's Arch., 1852, p. 312.- Kolliker, (A.,) 
et Lowig, De la composition et de la structure 
des enveloppes des Tuniciers, Ann. Sc. Nat. 3e ser., 
vol. 5, p. 193.- Huxley, (Th. II.,) Observations 
upon the Anatomy and Physiology of Salpa and 
Pyrosoma, Philos. Trans. R. Soc., 1851, IL, p. 567. 
- Eschricht, (D. F.,) Anatomisk-physiologiske 
Undersogelser over Salperne, Kibb. 1840, fig. - 
Steenstrup, (J.,) Ueber den Generationswechsel, 
q. a.-Vogt, (C.,) Bilder aus dem Thierleben, 
Frankfurt a. M., 1852, 8vo. - Muller, (H.,) Ueber 
Salpen, Zeitsch. f., wiss., Zook, vol. 4, p. 329. - 
Leuckart, (R.,) Zoologishe Untersuchungen, Gies- 
sen, 1853-54, 4to., fig., 2d Fasc. 
1 Carus, (C. G.,) Entwickelungsgeschichte unse- 
rer Flussmuschel, Leipzig, 1832, 4to., fig.- Quatre- 
fages, (Arm. de,) Sur 1'embryogenie des Tarets, 
Ann. Sc. Nat., 3e ser., 1849, vol. 2, p. 202. - Sur 
la vie interbranchiale des petites Anodontes, Ann. Sc. 
Nat., 2de ser., vol. 5, p. 321. - Loven, (S. L.,) Om 
Utvecklingen of Mollusca Acephala, Overs. Vet. 
Akad. Fbrhandl. Stockholm, 1849. - Germ. Muller's 
Arch., 1848, p. 531, and Wiegman's Arch., 1849, 
p. 312. - Prevost, (J. L.,) De la generation chez la 
moule des peintres, Mem. Soc. Phys. Geneve, 1825, 
vol. 3, p. 121. - Schmidt, (0.,) Ueber die Entwicke- 
lung von Cyclas calyculata Drap. Muller's Arch., 
1854, p. 428. - Leydig, (F.,) Ueber Cyclas cornea, 
Muller's Arch., 1855, p. 47. 
2 Carus, (C. G.,) Von den iiussern Lebensbe- 
dingungen der weiss- und kaltbliitigen Thiere, Leip- 
zig, 1824, 4to., fig. - Prevost, (J. L.,) De la 
generation chez le Lymnee, Mem. Soc. Phys., 
Geneve, vol. 5, p. 119. - Sars, (M.,) Zur Entwicke- 
lungsgeschichte der Mollusken und Zoophyten, 
Wiegm. Arch., 1837, I., p. 402; 1840, I., p. 196.- 
Zusatze zu der von mir gegebenen Dartstellung 
der Entwickelung der Nudibranchien. Wiegm. Arch. 
1845,1, p. 4. - Quatrefages, (Arm. de,) Memoire 
sur 1'Embryogenie des Planorbes et des Lymnees, 
Ann. Sc. Nat., 2de ser., vol. 2, p. 107. - VanBene- 
den, (P. J.,) Recherches sur le developpement des 
Aplysies, Ann. Sc. Nat., 2de ser., vol. 15, p. 123.- 
VanBeneden, (P. J.,) et Windischman, (Ch.,) 
Recherches sur 1'Embryogenie des Limaces, Mem. 
Ac. Brux., 1841. - Jacquemin, (Em.,) Sur le 
developpement des Planorbes, Ann. Sc. Nat., vol. 5, 
p. 117; Nov. Act. Nat. Cur.,'vol. 18. - Dumor- 
tier, (B. C.,) Memoire sur les evolutions de 
1'embryon dans les Mollusques Gasteropodes, Mem. 
Ac. Brux., 1836, vol. 10. - Laurent, (J. L. M.,) 
Observations sur le developpement de 1'oeuf des 
Limaces, Ann. Sc. Nat., vol. 4, p. 248. - Pouciiet, 
(F. A.,) Sur le developpement de 1'embryon des 
Lymnees, Ann. Sc. Nat., 2de ser., vol. 10, p. 63.- 
Vogt, (C.,) Recherches sur 1'Embryologie de 1'Ac- 
taeon, Ann. Sc. Nat., 3e ser., 1846, vol. 6, p. 5. - 
Beitrag zur Entwickelungsgeschichte eines Cepha- 
lophoren, Zeitsch. f. wiss. Zool., 1855, vol. 7, p. 162. 
- Schultze, (M.,) Ueber die Entwickelung des 
Tergipes lacinulatus, Wiegm. Arch., 1849, I., p. 268. 
- Warneck, (N. A.,) Ueber die Bildung und 
Entwickelung des Embryo bei Gasteropoden, Bull. 
Soc. Imp., Moscou, 1850, vol. 23, I., p. 90. - 
Schmidt, (O.,) Ueber die Entwickelung von Limax 
agrestis, Muller's Arch., 1851, p. 278.- Leydig, 
(F.,) Ueber Paludina vivipara, ein Beitrag zur 
nahern Kenntniss dieses Thieres in embryologischer, 
anatomischer und histologischer Beziehung, Zeitsch. 74 
ESSAY ON CLASSIFICATION. 
Part I. 
in their development than the Lamellibranchiata. Even among the terrestrial and 
aquatic Puhnonata there are striking differences. Some of the Pectinibranchiata are 
remarkable for the curious cases in which their eggs are hatched and the young 
developed, to an advanced state of growth. The cases of Pyrula and Strombus are 
among the most extraordinary of these organic nests. The embryology of Cepha- 
lopods 1 has been masterly illustrated by Kolliker. 
There is still much diversity of opinion among naturalists, respecting the limits 
of Articulata; some being inclined to separate the Arthropoda and Worms as dis- 
f. wiss. Zool., 1850, vol. 2, p. 125. - Kolliker, 
(A.,) q. a., Zeitsch. f. wiss. Zool., vol. 4, p. 333 and 
3G9. - Muller, (J.,) Ueber verschiedene Formen 
von Seethieren, Muller's Arch., 1854, p. 69. - Ueber 
Synapta digitata und fiber die Erzeugung von 
Schnecken in Holothurien, Berlin, 1852, 4to. fig. - 
The remarkable case described in this paper, admits 
of an explanation which Muller has not considered. 
It is known, that fishes penetrate into the cavity of 
the body of Holothuriae, through its posterior open- 
ing. (De Bosset, Notice, etc., Mem. Soc. Sc. Nat., 
Neuch., 1839, vol. 2, 4to.) The similarity of Ento- 
concha mirabilis with the embryonic shell of various 
species of Littorinae, such as Lacuna vincta, the 
development of which I had an opportunity of study- 
ing, suggests the possibility, that some species of this 
family, of which there are many very small ones, 
select the Synapta as their breeding place and leave 
it after depositing their eggs, which may become con- 
nected with the Synapta, as our Mistletoe or the 
Orobanche and many other parasitic plants, with the 
plants upon which they grow. - Gegenbauer, (C.,) 
Beitrage zur Entwickelungsgeschichte der Landgas- 
teropoden, Zeitsch. f. wiss. Zool., 1852, vol. 3, p. 371.- 
Untersuchungen fiber Pteropoden und Heteropoden, 
Leipzig, 1855, 1 vol., 4to. fig. - Koren, (J.,) und 
Danielssen, (D. C.,) Bitrag til Pectinibranchiernes 
Udviklingshistorie, Bergen, 1851, 8vo.; French Ann. 
Sc. Nat., 1852, vol. 18, p. 257, and 1853, vol. 19, 
p. 89; also Germ, in Wiegm. Arch., 1853, p. 173.- 
Nordmann, (Al. V.,) Versuch einer Monographic 
von Tergipes Edwardsii, St. Petersburg, 1844, 4to.- 
Leuckart, (R.,) Zoologische Untersuchungen, Gies- 
sen, 1853-54, 4to., fig., 3d Fasc.- Huxley, (Tn. II.,) 
On the Morphology of the Cephalous Mollusca, etc., 
Phils. Trans. R. Soo., 1853, I., p. 29. - Hogg, 
(Jabez,) On the Development and Growth of the 
Watersnail, Quart. Mier. Journ., 1854, p. 91.- Reid, 
(J.,) On the Development of the Ova of the Nudi- 
branchiate Mollusca, Ann. and Mag. Nat. Hist., 1846, 
vol. 17, p. 377.- Carpenter, (W. B.,) On the 
Development of the Embryo of Purpura Lapillus, 
Quart. Mier. Journ., 1845, p. 17. 
1 Kolliker, (Alb.,) Entwickelungsgeschichte 
der Cephalopoden, Zurich, 1844, 4to., fig.- Van- 
Beneden, (P. J.,) Recherches sur 1'Embryogenie 
des Sepioles, N. Mem. Acad. Brux., vol. 14, 1841. 
- Coldstream, (Z.,) On the Ova of Sepia, Lond. 
and Ed., Phil. Mag., Oct., 1833. - Duges, (Ant.,) 
Sui* le developpement de 1'embryon chez les Mollus- 
ques Cephalopodes, Ann. Sc. Nat., vol. 8, p. 107. - 
Rathke, (H.,) Perothis, ein neues genus der Cepha- 
lopoden, Mem. Ac. St. Petersb., 1834, vol. 2, p. 
149. (Is the young of some Loligoid Cephalopod.) 
Milne-Edwards, (II.,) Observations sur les sper- 
matophores des Mollusques Cephalopodes, etc., Ann. 
Sc., n., 2de ser., vol. 3, p. 193. - Kolliker, (A.,) 
Hectocotylus Argonautae Delle Chiaje und Hect. 
Tremoctopodis K., die Mannchen von Argonauta 
Argo und Tremoctopus violaceus, Ber. Zool. Anst. 
Wurzburg, 1849, p. 69. - Muller, (II.,) Ueber 
das Mannchen von Argonauta Argo und die Hecto- 
cotylen, Zeitsch. f. wiss. Zool., vol. 4, p. 1. -Vera- 
ny, (J. B.,) et Vogt, (C.,) Memoire sur les Hec- 
tocotyles et les males de quelques Cephalopodes, 
Ann. Sc. n., 3e ser., 1852, vol. 17, p. 147.- Rou- 
lin, (F. D.,) De la connaissance qu'ont eue les 
anciens du bras copulateur chez certains Cephalo- 
podes, Ann. Sc. n., 3e ser., 1852, vol. 17, p. 188.- 
Leuckart, (R.,) Zool. Unters. q. a. Chap. I. 
METAMORPHOSES OF ANIMALS. 
75 
tinct brandies, while others unite them into one. I confess I cannot see the ground 
for a distinction. The worm-like nature of the larvaa of the majority of Arthropods 
and the perfect homology of these larvae with the true Worms, seem to me to 
show beyond the possibility of a doubt, that all these animals are built upon one 
and the same plan, and belong, therefore, to one branch, which contains only three 
classes, if the principles laid down in my second chapter are at all correct, namely, 
the Worms, Crustacea, and Insects. As to the Protozoa, I have little confidence 
in the views generally entertained respecting their nature. Having satisfied myself 
that Colpoda and Paramecium are the brood of Planariae, and Opalina that of Dis- 
toma, I see no reason, why the other Infusoria, included in Ehrenberg's division 
Enterodela,1 should not also be the brood of the many lower Worms, the develop- 
ment of which has thus far escaped our attention. Again, a comparison of the early 
stages of development of the Entomostraca with Rotifera might be sufficient to show, 
what Burmeister, Dana, and Leydig have proved in another way, that Rotifera are 
genuine Crustacea, and not Worms. The vegetable character of most of the Anen- 
tera has been satisfactorily illustrated. I have not yet been able to arrive at a 
definite result respecting the Rhizopods, though they may represent, in the type of 
Mollusks, the stage of yolk segmentation of Gasteropods. From these remarks it 
should be inferred, that I do not consider the Protozoa as a distinct branch of the 
animal kingdom, nor the Infusoria as a natural class.2 
Taking the class of Worms, in the widest sense, it would thus embrace the 
1 That Vorticellidae are Bryozoa, has already 
been stated above. 
2 Schultze, (M.,) Beitriige zur Naturgeschichte 
den Turbellarien, Greifswald, 1851, 4to., fig.- Zoo- 
logische Skizzen, Zeitsch. f. wiss. Zool. 1852, vol. 4, 
p. 178. - Muller, (J.,) Ueber eine eigenthumliche 
Wurmlarve, etc., Archiv, 1850, p. 485.- Desor, 
(E.,) On the Embryology of Nemertes, with an Ap- 
pendix on the Embryonic Development of Polynoe, 
Boston Journ. Nat. Hist. 1850, vol. 6, p. 1 ; Muller's 
Archiv, 1848, p. 511. - Agassiz, (L.,) Colpoda and 
Paramecium are larvae of Planariae, Proc. Am. Ass. 
Adv. Sc., Cambridge, 1849, p. 439. - Girard, (Ch.,) 
Embryonic Development of Planocera elliptica, Jour. 
Ac. Nat. Sc. Phil., 2d ser. 1854, vol. 2, p. 307.- 
Ehrenberg, (C. G.,) Die Infusionsthierchen, etc., 
q. a. - Kutzing, (F. T.,) Ueber die Verwandlung 
der Infusorien in niedere Algenformen, Nordhausen, 
1844, 4to. fig. - Siebold, (C. Th. E. v.,) Ueber 
einzellige Pflanzen und Thiere, Zeitsch. f. wiss. Zool. 
1849, vol. 1, p. 270. - Naegeli, (C.,) Gattungen 
einzelliger Algen, Zurich, 1849, 4to. fig. - Braun, 
(A.,) Algarum unicellularium genera nova et minus 
cognita, Leipzig, 1855, 4to. fig. - Cohn, (F.,) Bei- 
trage zur Entwickelungsgeschichte der Infusorien 
Zeitsch. f. wiss. Zool. 1851, vol. 3, p. 257. - Bei- 
trage zur Kenntniss der Infusorien, Zeitsch. f. wiss. 
Zool. 1854, vol. 5, p. 420. - Ueber Encystirung von 
Amphileptus fasciola, ibid. p. 434.-Schultze, (M.,) 
Ueber den Organismus der Polythalamien, Leipzig, 
1854, 1 vol. fol. fig.- Beobachtungen fiber die Fort- 
pflanzung der Polythalamien, Muller's Archiv, 1856, 
p. 165.-Auerbach, (L.,) Ueber die Einzelligkeit 
der Amoeben Zeitsch. f. wiss. Zool. 1855, vol. 7, 
p. 365. - Ueber Encystirung von Oxytricha Pellio- 
nella, Zeitsch. f. wiss. Zool. 1854, vol. 5, p. 430. - 
Cienkowsky, Ueber Cystenbildung bei Infusorien, 
Zeitsch. f. wiss. Zool. 1855, vol. 6, p. 301. 76 
ESSAY ON CLASSIFICATION. 
Part I. 
Helminths, Turbellarim, and Annulata. The embryology of these animals still requires 
careful study, notwithstanding the many extensive investigations to which they have 
been submitted; the intestinal Worms especially continue to baffle the zeal of 
naturalists, even now when the leading features of their development are ascertained. 
The Nematoids undergo a very simple development, without alternate generations, 
and as some are viviparous their changes can easily be traced.1 The Cestods and 
Cystici, which were long considered as separate orders of Helminths, are now known 
to stand in direct genetic connection with one another, the Cystici being only 
earlier stages of development of the Cestods.2 The Trematods exhibit the most 
complicated phenomena of alternate generations; but as no single species has thus 
far been traced through all the successive stages of its transformations, doubts are 
1 Stein, (F.,) Beitriige zur Entwickelungsges- 
chichte der Eingeweidewfirmer, Zeitsch. f. wiss. Zool., 
1852, vol. 4, p. 196. - Nelson, (H.,) On the Re- 
production of the Ascaris Mystax, Philos. Trans. 
R. Soc., 1852, IL, p. 563. -Grube, (E.,) Ueber 
einige Anguillulen und die Entwickelung von Gor- 
dius aquaticus, Wiegmann's Archiv, 1849, I., p. 358. 
- Siebold, (C. Th. E. v.,) Ueber die Wanderung 
der Gordiaceen, Uebers. d. Arb. und Ver. schles. 
Ges. f. vaterl. Kultur., 1850, p. 38. - Meissner, 
(G.,) Beitriige zur Anatomie und Physiologic von 
Mermis albicans, Zeitsch. f. wiss. Zool., 1853, vol. 5, 
p. 207. - Beobachtungen fiber das Eindringen der 
Saamenelemente in den Dotter, Zeitsch. f. wiss. 
Zool., 1855, vol. 6, p. 208, und 272. - Beitriige zur 
Anatomie und Physiologic der Gordiaceen, Zeitsch. f. 
wiss. Zool., 1855, vol. 7, p. 1. - Kolliker, (A.,) 
Beitriige zur Entwickelungsgeschichte wirbelloser 
Thiere, Muller's Archiv, 1843, p. 68. - Bagge, 
(H.,) Dissertatio inaug. de evolutione Strongyli au- 
ricularis et Ascaridis acuminata;, Erlangen, 1841, 
4to. fig. - Leidy, (Jos.,) A Flora and Fauna within 
living Animals, Smithson. Contrib. 1853, 4to. fig.- 
Luschka, (H.,) Zur Naturgeschichte der Trichina 
spiralis, Zeitsch. f. wiss. Zool. 1851, vol. 3, p. 69.- 
Bischoff, (Th.,) Ueber Ei- und Samenbildung und 
Befruchtung bei Ascaris Mystax, Zeitsch. f. wiss. 
Zool., 1855, vol. 6, p. 377. - Widerlegung, des von 
Dr. Keber bei den Najaden und Dr. Nelson bei 
den Ascariden behaupteten Eindringens der Sper- 
matozoiden in das Ei, Giessen, 1854, 4to. fig. - 
Bestiitigung des von Dr. Newport bei den Batra- 
chiern und Dr. Barry bei den Kaninchen behaupte- 
ten Eindringens der Spermatozoiden in das Ei, Gies- 
sen, 1854, 4to. 
2 Van Beneden, (P. J.,) Les Helminthes Ces- 
toides, etc., Bullet. Ac. Belg., vol. 16, et seq.; Mem. 
Ac. Brux., 1850, vol. 17, et seq. - Kolliker, (A.,) 
Beitriige, etc., q. a.; p. 81.- Siebold, (C. Th. E. 
v.,) Ueber den Generationswechsel der Cestoden, etc., 
Zeitsch. wiss. Zool., 1850, vol. 2, p. 198. - Ueber 
die Umwandlung von Blasenwiirmer in Bandwiirmer, 
Uebers. d. Arb. und Ver. d. scliles. Ges. f. vaterl. 
Kultur, 1852, p. 48. - Ueber die Verwandlung des 
Cysticercus pisiformis in Taenia serrata, Zeitsch. f. 
wiss. Zool., 1853, vol. 4, p. 400. - Ueber die Ver- 
wandlung der Echinococcus-Brut in Tamien, Ibid., 
1853, p. 409. - Ueber die Band-und Blasenwiirmer, 
nebst einer Einleitung uber die Entstehung der Ein- 
geweidewiirmer, Leipzig, 1854, 8vo. fig. - Huxley, 
(Th. II.,) On the Anatomy and Development of 
Echinococcus veterinorum, Ann. and Mag. Nat. Hist. 
2d ser., vol. 14, p. 379. - Kuchenmeister, (Fr.,) 
Ueber die- Umwandlung der Finnen (Cysticerci) in 
Bandwiirmer (Taeniae) Prag. Vierteljahrssch, 1852, 
p. 106. - Wagener, (R. G.,) Die Entwickelung der 
Cestoden, Bonn, 1855, 1 vol. 4to. fig. - Meissner, 
(G.,) Zur Entwickelungsgeschichte und Anatomie 
der Bandwiirmer, Zeitsch. f. wiss. Zool., 1854, vol. 
5, p. 380. - Leuckart, (R.,) Erziehung des Cysti- 
cercus fasciolaris aus den Eiern der Taenia crassi- 
collis, Zeitsch. f. wiss. Zool. 1854, vol. 6, p. 139. Chap. I. 
METAMORPHOSES OF ANIMALS. 
77 
still entertained respecting the genetic connection of many of the forms which 
appear to belong to the same organic cycle.1 It is also still questionable, whether 
Gregarime and Psorospermia are embryonic forms or not, though the most recent 
investigations render it probable that they are.2 The development of the Annu- 
lata, as they are now circumscribed, exhibits great variety;3 some resemble more 
the Nematods, in their metamorphoses, while others, the Leeches for instance, 
1 Nordmann, (Al. v.,) Micrographische Beitriige 
zur Naturgeschichte der wirbellosen Thiere, Berlin, 
1832, 4to. tig. - Bojanus, (L.,) Zerkarien und ihr 
Fundort, Isis 1818, vol. 4, p. 729. - Enthehnin- 
tica Isis 1821, p. 162. - Carus, Beobachtungen iiber 
einen merkwiirdigen Eingeweidewurm, Leucochlori- 
dium paradoxuni, Nov. Act. Ac. Nat. Cur., vol. 17, 
p. 85. - Siebold, (C. Th. E. v.,) Helminthologische 
Beitriige, Wiegman's Archiv, 1835, vol. 1, p. 45.- 
Ueber die Conjugation des Diplozoon paradoxum, 
etc., Zeitsch. f. wiss., Zool., 1851, vol. 3, p. 62. - 
Gyrodactylus, ein ammendes Wesen. Zeitsch. f. wiss. 
Zool., 1849, vol. 1, p. 347. - Steenstrup, (J.,) Ge- 
nerationswechsel, etc., q. a.-Bilharz, (Th.,) Ein 
Beitriig zur Helminthographia humana, Zeitsch. f. 
wiss. Zool., 1852, vol. 4, p. 59.- Agassiz, (L.,) Zoo- 
logical Notes, etc., Amer. Journ. Sc. and A. 1852, vol. 
13, p. 425. - Baer, (K. E. v.,) Beitriige zur Kennt- 
niss der niedern Thiere, Act. Nov. Nat. Cur. 1827, 
vol. 13. - Aubert, (H.,) Ueber das Wassergefass- 
system, die Geschlechtsverhiiltnisse, die Eibildung 
und die Entwickelung von Aspidogaster conchicola, 
Zeitsch. f. wiss. Zool. 1855, vol. 6, p. 349. - Leidy, 
(Jos.,) Description of two new Species of Distoma, 
with the partial History of one of them, Jour. Ac. 
Nat. Sc. Phil. 1850, vol. 1, p. 301, fig. 
2 Muller, (J.,) Ueber eine eigenthiimliche 
krankhafte parasitische Bildung, etc., Miiller's 
Archiv, 1841, p. 477. - Ueber parasitische Bildun- 
gen etc., Muller's Archiv, 1842, p. 193.-Dufour, 
(L.,) Note sur la Gregarine, etc., Ann. Sc. Nat., 
1828, vol. 13, p. 366, fig. - Ibid., 2de ser., 1837, 
vol. 7, p. 10.-Siebold, (C. Th. E. v.,) Beitriige 
etc., q. a.; p. 56-71.- Hammers chmidt, (C. Ed.,) 
Helminthologische Beitriige, Isis 1838, p. 351.- 
Kolliker, (A.,) Die Lehre von der thierischen 
Zelle, etc., Zeitsch. wiss. Botanik. 1845, vol. i., p. 46, 
and p. 97. - Beitriige zur Kenntniss niederer Thiere, 
Zeitsch. f. wiss. Zool. 1848, vol. i. p. 1. - Henle, 
(J.,) Ueber die Gattung Gregarina, Muller's Archiv, 
1845, p. 369. - Frantzius, (Al. v.,) Observationes 
quaedam de Gregarinis, Berolini, 1846.-Stein, (F.,) 
Ueber die Natur der Gregarinen, Muller's Archiv, 
1848, p. 182, fig. - Bruch, (C.,) Einige Bemer- 
kungen iiber die Gregarinen, Zeitsch. f. wiss. Zool. 
1850, vol. 2, p. 110. - Leydig, (F.,) Ueber Proro- 
spermien und Gregarinen, Muller's Archiv, 1851, 
p. 221. - Leidy, (Jos.,) On the Organization of the 
Genus Gregarina, Trans. Amer. Phil. Soc. 1851, vol. 
10, p. 233. - Some Observations on Nematoidea im- 
perfecta and Descriptions of three parasitic Infusoria, 
Trans. Amer. Phil. Soc. 1851, vol. 10, p. 241.- 
Lieberkuhn, (N.,) Ueber die Psorospermien, Mul- 
ler's Archiv, 1854, p. 1. 
8 Weber, (E. IL,) Ueber die Entwickelung von 
Ilirudo medicinalis, Meckel's Archiv, 1828, p. 366, 
fig. - Filippi, (Fil. de,) Sopra l'anatomia e lo svi- 
luppo delle Clepsine, Pavia, 1839, 8vo. fig. - Loven, 
(J.,) Beobachtungen iiber die Metamorphose einer 
Annelide, K. Vet. Ac. Handl. 1840, Wiegmann's 
Archiv, 1842, vol. i., p. 302. - Oersted, (A. S.,) 
Ueber die Entwickelung der Jungen bei einer Anne- 
lide, etc., Wiegmann's Archiv, 1845, vol. i., p. 20.- 
Sars, (M.,) Zur Entwickelung der Anneliden, Wieg- 
mann's Archiv, 1845, vol. i., p. 11. - Menge, (A..) 
Zur Roth-Wiirmer Gattung Euaxes, Wiegmann's 
Archiv, 1845, vol. i., p. 24. - Grube, (A. E.,) Zur 
Anatomie und Entwickelung der Kiemenwiirmer, 
Kbnigsberg, 1838, 4to.-Actinien, Echinodermen und 
Warmer, etc., Kbnigsberg, 1840, 4to. fig. - Unter- 
suchungen iiber die Entwickelung der Clepsine, Dor- 
pat, 1844. - Edwards, (H. Milne,) Observations 
sur le developpement des Annelides, Ann. Sc. Nat. 
3e ser. 1845, vol. 3, p. 145. - Koch, (H.,) Einige 78 
ESSAY ON CLASSIFICATION. 
Part 1. 
approximate more the type of the Trematods. The Sipunculoids appear to be more 
closely related to the Annulata than to the Holothurioids.1 
The class of Crustacea, on the contrary, may be considered as one of the best 
known, as far as its zoological characters and embryonic growth are concerned; the 
only point still questioned being the relationship of the Rotifera.2 In their mode 
of development the Lernmans, the Entomostraca proper, and the Cirripeds agree as 
closely with one another as they differ from the higher Crustacea. This con- 
formity3 is the more interesting, as the low position the Entomostraca hold in the 
Worte zur Entwickelungsgeschichte der Eunice, mit 
einem Nachworte von Kolliker, N. Denksch. Schw. 
Gesell., 1847, vol. 8, 4to. fig. - Quatreeages, (A. 
de,) Memoire sur 1'Embryogenie des Annelides, Ann. 
Sc. Nat. 3e ser., 1848, vol. 10, p. 153, fig.-Desor, 
(Ed.,) On the Embryology, etc., q. a. - Leidy, 
(Jos.,) Descriptions of some American Annelida 
abranchia, Journ. Ac. Nat. Sc. Phil. 1850, vol. 2, 
p. 43, fig., (Lumbricillus contained several thousand 
large Leucophrys. The case related here by Leidy 
seems to me to indicate rather the hatching of Opali- 
nas from the eggs of Lumbricillus, than the presence 
of parasitic Leucophrys.) - Schultze, (M.,) Ueber 
die Fortpflanzung durch Theilung bei Nais probosci- 
dea, Wiegman's Archiv, 1849, L, p. 293; id. 1852, 
L, p. 3. - Zoologische Skizzen (Arenicola piscat.) 
Zeitsch. f. wiss. Zool. 1852, vol. 4, p. 192.- Busch, 
(W.,) Beob. fiber Anat, und Entw. q. a. (p. 55.) - 
Muller, (M.,) Observationes anatomical de Vermi- 
bus quibusdam maritimis, Berolini, 1852, 4to.; Mul- 
ler's Archiv, 1852, p. 323. - Ueber die weitere 
Entwickelung von Mesotrocha sexoculata, Muller's 
Archiv, 1855, p. 1.-Ueber Sacconereis helgolandica, 
Muller's Archiv, 1855, p. 13.- Krohn, (A.,) Ueber 
die Ercheinungen bei der Fortpflanzung von Syllis, 
Wiegman's Archiv, 1852, L, p. 66. - Ueber die 
Sprosslinge von Autolytus prolifer Gr., Miiller's Ar- 
chiv, 1855, p. 489. - Leuckart, (R.,) Ueber die 
ungeschlechtliche Vermehrung bei Nais proboscides, 
Wiegman's Archiv, 1851, p. 134. - Ueber die Ju- 
gendzustiinde einiger Anneliden, Wiegman's Archiv, 
1855, L, p. 63. 
1 Peters, (W.) Ueber die Fortpflanzungsorgane 
des Sipunculus, Muller's Archiv, 1850, p. 382.- 
Muller, (M.,) Ueber eine den Sipunculidcn ver- 
wandte Wurmlarve, Muller's Archiv, 1850, p. 439. 
- Krohn, (A.,) Ueber die Larve des Sipunculus 
nudus, etc., Muller's Archiv, 1851, p. 368.- 
Schmarda, (L.,) Zur Naturgeschichte der Adria 
(Boneilia viridis) Denksch. Wien. Akad. 1852, vol. 
4, p. 117, fig. - Gegenbauer, (C.,) Ueber die Ent- 
wickelung von Doliolum, der Scheibcnquallen und 
von Sagitta, Zeitsch. f. wiss. Zool. vol. 5, p. 13. 
2 Ehrenberg, (C. J.,) Die Infusionsthierchen, 
etc., q. a. - Dalrymple, (J..) Description of an In- 
fusory Animalcule allied to the Genus Notommata. 
Philos. Trans. 1844, II., p. 331. - Naegeli, (II.,) 
Beitrage zur Entwickelungsgeschichte der Rader- 
thiere, inaug. Diss., Zurich, 1852, 8vo. fig. - Leydig, 
(Fr.,) Ueber den Bau und die systematische Stel- 
lung der Raderthiere, Zeitsch. f. wiss. Zool. 1851, 
vol. 6, p. 1. - Zur Anatomie und Entwickelungsges- 
chichte der Lacinularia socialis, Zeitsch. f. wiss. Zool. 
1852, vol. 3, p. 452. - Cohn, (F.,) Ueber die Fort- 
pflanzung der Raderthiere, Zeitsch. f. wiss. Zool., 
1855, vol. 7, p. 431. - Huxley, (Th. H.,) Lacinula- 
ria socialis, Trans. M. Soc., Mier. Journ. 1852, p. 12. 
- Williamson, (W. C.,) On the Anatomy of Meli- 
certa ringens. Quart. Mier. Journ. 1852, p. 1. 
8 Jurine, (L.,) Histoire des Monocles qui se 
trouvent aux environs de Geneve, Paris, 1806, 4to. 
fig. - Edwards, (II. Milne,) in Cuvier, Regn. An. 
edit, illustr. q. a. Crustacds; represents young Li- 
mulus.- Zaddach, (E. G.,) De Apodis cancrifor- 
mis Anatome et Historia evolutionis Bonnae, 1841, 
4to. fig. - Nordmann, (Al. v.,) Microgr. Beitr. q. 
a. - Leydig, (Fr.,) Ueber Argulus foliaceus, ein 
Bcitrag zur Anatomie, Histologie und Entwickelungs- 
geschichte dieses Thieres, Zeitsch. f. wiss. Zool. 1850, 
vol. 2, p. 323. - Ueber Artemia salina und Branchi- Chap. I. 
METAMORPHOSES OF ANIMALS. 
79 
class of Crustacea, agrees strikingly with their early appearance in geological times, 
while the form of the adult Cirripeds1 and that of the Lernmans would hardly 
lead one to suspect their near relationship, which has, indeed, been quite overlooked 
until Embryology showed that their true position is among Crustacea. In the 
development of the higher Crustacea,2 their superior rank is plainly exhibited, and 
few types show more directly a resemblance, in their early stages of development, 
to the lower members of their class, than the Brachyura. 
In the class of Insects, I include Myriapods, Arachnoids, and the true Insects, 
as, according to the views expressed hereafter, these natural groups constitute only 
different degrees of complication of the same combination of organic systems, and 
must, therefore, be considered as natural orders of one and the same class. This 
class, though very extensively studied in a zoological and anatomical point of view, 
and as far as the habits of its representatives are concerned, still requires, however, 
much patient work, as the early embryonic development of these animals has been 
much less studied than their later transformations.3 The type of the Arachnoids 
pus stagnalis, Zeitsch. f. wiss. Zool. 1851, vol. 3, p. 
280. - VanBeneden, (P. J.,) Recherches sur quel- 
ques Crustaces inferieurs Ann. Sc. Nat. 3e ser. 1851, 
vol. 16, p. 71. - Memoire sur le developpement et 
1'organisation des Nicothoes, Ann. Sc. Nat. 3e ser. 
1850, vol. 13, p. 354. - Barrande, (J.,) Syst. sil. q. 
a.; contains the first observations upon the transfor- 
mations of Trilobites. 
1 Thompson, (W. V.,) Zoological Researches 
and Illustrations, or Natural History of nondescript 
or imperfectly known Animals, Cork, 1828-34, 8vo., 
fig. - Burmeister, (H.,) Beitrage zur Naturge- 
schichte der Rankenfusser, (Cirripedia,) Berlin, 1834, 
1 vol. 4to. fig.-Goodsir, (H. D. S.,) On the Sexes, 
Organs of Reproduction, and Development of Cirri- 
peds, Ed. N. Phil. J. 1843, No. 35, p. 88, fig.- 
Martin St. Ange, (G. J.,) Memoire sur 1'organisa- 
tion des Cirripedes et sur leurs rapports naturels 
avec les animaux articules, Ann. Sc. Nat. 1831, 
p. 366, fig. - Darwin, (Ch.,) A Monograph of the 
sub-class Cirripedia, with Figures of all the Species, 
London, 1851, 2 vols. 8vo. (Ray Society.) - Bate, 
(Spence,) On the Development of the Cirripedia, 
Ann. and Mag. Nat. Hist. 2d ser. vol. 8, p. 324. 
2 Rathke, (H.,) Untersuchungen fiber die Bil- 
dung und Entwickelung des Flusskrebses, Leipzig, 
1829, 1 vol. fol. fig. - Beitrage zur Fauna Norve- 
gica, Act. Nov. Ac. Leop. Cass. vol. 20. - Beitrage 
zur vergleichenden Anatomie und Physiologic, Rei- 
sebemerkungen aus Skandinavien, Dantzig, 1842, 
4to. - Zur Morphologic, Reisebemerkungen aus Tau- 
rien, Riga und Leipzig, 1837, 4to. fig. - Ueber die 
Entwickelung der Decapoden, Muller's Archiv, 1836, 
p. 187, Wiegman's Archiv, 1840, I., p. 241.- 
Beobachtungen und Betrachtungen uber die Entwi- 
ckelung der Mysis vulgaris, Wiegman's Archiv, 1839, 
p. 195, fig. - Erdl, (M. P.,) Entwickelung des 
Hummereies, Munchen, 1843, 4to. fig. - Edwards, 
(H. Milne,) sur la generation des Crustaces, Ann. 
Sc. Nat. 1829. - Observations sur les changements 
de forme que divers Crustaces eprouvent dans le 
jeune age, Ann. Sc. Nat. 2de ser. vol. 3, p. 321. 
- Agassiz, (L.,) Zoological Notes, etc., Am. Jour. 
Sc. and A., 1852, p. 426. - Recent Researches, etc., 
Am. Journ. Sc. and A., 1852, vol. 16, p. 136. 
3 Herold, (M.,) Entwickelungsgeschichte der 
Schmetterlinge, etc., Kassel und Marburg, 1815, 4to. 
fig. - Disquisitiones de animalium vertebris caren- 
tium in ovo formatione, Frankfurt a. M., 1835, fol. 
fig. - Rathke, (H.,) Entwickelungsgeschichte der 
Blatta germanica, Meckel's Archiv, 1832. - Zur 
Entwickelungsgeschichte der Maulwurfsgrille (Gryl- 80 
ESSAY ON CLASSIFICATION. 
Part I. 
embraces two groups, the Acari and the Arachnoids proper, corresponding respec- 
tively in this class to the Entomostraca and the higher Crustacea. The embryo 
of the Acari resembles somewhat that of the Entomostraca, whilst that of the true 
Spiders1 recalls the metamorphosis of the higher Crustacea. On the ground of the 
similarity of their young, some animals, formerly referred to the class of Worms,2 
are now considered as Arachnoids; but the limits between the aquatic Mites and 
the Pycnogonums are not yet quite defined. 
In the branch of Vertebrata, all classes have been extensively studied, and as 
far as the principal types are concerned, the leading features of their development 
are satisfactorily known. Much, however, remains to be done to ascertain the minor 
modifications characteristic of the different families. It may even be, that further 
investigations will greatly modify the general classification of the whole branch. 
The class of Fishes3 may require subdivision, since the development of the Plagios- 
lotalpa vulgaris,) Muller's Archiv, 1844, p. 27.- 
Kolliker, (A.,) Observationes de prima Insecto- 
rum Genesi, Turici, 1842, 4to. fig. - Zaddach, (G.,) 
Die Entwickelung des Phryganiden Eies, Berlin, 
1 vol. 4to. 1854. - Leuckardt, (R.,) Ueber die 
Micropyle und den feinern Bau der Schalenhaut bei 
den Insekteneiern, Muller's Arch., 1855, p. 90.- 
Newport, (Geo.,) On the Organs of Reproduction 
and the Development of Myriapoda, Phil. Trans. R. 
Soc., 1842,11. p. 99. - Stein, (Fr.,) Vergeichende 
Anatomie und Physiologic der Insecten, Iste Monogr., 
Die weiblichen Geschlechtsorgane der Kafer, Berlin, 
1847, fol. fig. - Siebold, (C. Th. E. v.,) Ueber die 
Fortpflanzung von Psyche, Zeitsch. f. wiss. Zool., 
1848, vol. l,p. 93. - Leydig, (Fr.,) Einige Remer- 
kungen fiber die Entwickelung der Blattlause, Zeitsch. 
f. wiss. Zool., 1850, vol. 2, p. G2. - Meyer, (H.,) 
Ueber die Entwickelung des Fettkorpers, der Tra- 
cheen und der keimbereitenden Geschechtstheile bei 
den Lepidopteren, Zeitsch. f. wiss. Zool., 1849, vol. 1. 
- Burnett, (W. J.,) Researches on the Develop- 
ment of viviparous Aphides, Amer. Joum. Sci. and 
Arts, 1854, vol. 17, p. 62 and 261. - As far as the 
metamorphoses of Insects, after the eclosion of the 
larva, are concerned, I must refer to the works of 
Reaumer and Roesel already quoted, and to almost 
every modern book upon Entomology. The meta- 
morphoses of North American Insects are minutely 
described in Harris's Report, q. a. 
1 Herold, (M.,) De generatione Aranearum in 
ovo, Marburgi, 1824, fol. fig. - Rathke, (II.,) 
Ueber die Entwickelung des Scorpions; Zur Mor- 
phologic, q. a. - VanBeneden, (P. J.,) Recherches 
sur 1'Histoire naturelie et le developpement de 1'Atax 
ypsilophora, Mdm. Ac. Brux., 1850, vol. 24, p. 444. 
- Wittich, (W. II. v.,) Observationes qusedam de 
aranearum ex ovo evolutione, Diss, inaug. Halis 
Sax., 1845. - Die Entstehung des Arachnideneies 
im Eierstock, Muller's Arch., 1849, p. 113. - Carus, 
(J. V.,) Ueber die Entwickelung des Spinneneies, 
Zeitsch. f. wiss. Zool., 1850, vol. 2, p. 97. - Dujar- 
din, (F.,) Memoire sur des Acariens sans bouches, 
dont on a fait le genere Hypopus et qui sont le 
premier age des Gamaoses, Ann. Sc. Nat., 1849, 
vol. 12, p. 243 et 259. 
2 Kaufmann, (Jos.,) Ueber die Entwickelung 
und zoologische Stellung der Tardigraden, Zeitsch. 
f. wiss. Zool. 1851, vol. 3, p. 220. - VanBeneden, 
(P. J.,) Recherches sur 1'organisation et le develop- 
pement des Linguatules (Pentastoma,) Mem. Ac. 
Brux. vol. 15, I., p. 188. - Schubert, (T. D.,) 
Ueber Entwickelung von Pentastomum taenioides 
Zeitsch. f. wiss. Zool. 1852, vol. 4, p. 117. - Wil- 
son, (E.,) Researches into the Structure and De- 
velopment of a newly discovered Parasitic Animal- 
cule of the Human Skin, Phil. Trans. R. Soc. 1844, 
p. 305. 
8 ForChhammer, (G.,) De Blennii vivipari Chap. I. 
METAMORPHOSES OF ANIMALS. 
81 
toms differs greatly from that of the ordinary fishes. As it now stands in our sys- 
tems, the class of Fishes is certainly the most heterogeneous among Vertebrata. 
formatione et evolutione observationes, Kiel, 1819, 
4to. - Prevost, (J. L.,) De la generation chez le 
Sechot (Cottus Gobio), Mem. Soc. Phys, et Hist. Nat., 
Geneve, vol. 4, 1828, 4to.- Rathke, (H.,) Beitriige 
zur Geschichte der Thierwelt, Halle, 1820-27, 4 vols. 
4to. fig. - Abhandlungen zur Bildungs- und Ent- 
wickelungsgeschichte des Menschen und der Thiere. 
Leipzig, 1832-33, 2 vols. 4to. fig. - Ueber das Ei 
einiger Lachsarten, Meckel's Archiv, 1832, p. 392.- 
Baer, (K. E. v.,) Untersuchungen fiber die Ent- 
wickelungsgeschichte der Fische, Leipzig, 1835, 4to. 
- Also Entw. der Thiere, q. a., vol. 2d. - Davy, 
(J.,) On the Development of the Torpedo, Philos. 
Trans. R. Soc., 1834. - Filippi, (Fil. de,) Memoria 
sullo sviluppo. del Gobius fluviatilis, Anna. Medic., 
Milano, 1841, 8vo. fig. - Rusconi, (M.,) Sopra la 
fecondatione artificiale nei pesci, Giorn. delle Sc. 
Med.-chir., Pavia, vol. 9 ; tranls. in Muller's Archiv, 
1840, p. 185. - Lettre sur Ies changements que les 
oeufs de Poissons eprouvent avant qu'ils aient pris la 
forme d'embryon, Ann. Sc. Nat., 2de ser. vol. 5; 
transl. Mag. Zool. and Bot., L, p. 586. - Agassiz, 
(L.,) Histoire naturelle des Poissons d'eau douce de 
1'Europe centrale, vol. 1. Embryologie des Salmones, 
par C. Vogt, Neuchatel, 1842, 8vo. atlas fol. These 
investigations were made under my direction and 
supervision. - Muller, (J.,) Ueber den glatten Hai 
des Aristoteles, und fiber die Verschiedenheiten unter 
den Haifishen find Rochen in der Entwickelung des 
Eies, Berlin, 1842, fol. fig. - Leuckart, (F. S.,) 
Untersuchungen fiber die aussern Kiemen der Em- 
bry onen von Rochen und Haien, Stuttgardt, 1836, 
8vo. fig. - Leydig, (Fr.,) Beitriige zur microscopis- 
chen Anatomie und Entwickelungsgeschichte der 
Rochen und Haie, Leipzig, 1852, 1 vol. 8vo. fig.- 
Carus, (C. G.,) Erliiuterungstafeln, etc., No. 3, Leip- 
zig, 1831, fol. fig. - Shaw, (J.,) Account of some 
Experiments and Observations on the Parr, etc., 
Edinb. New Phil. Journ., vol. 21, p. 99. - On the 
Development and Growth of the Fry of the Salmon, 
etc., Ibid. vol. 24, p. 165; also Ann. Nat. Hist., I. 
p. 75, and IV. p. 352. - Yarrell, (W.,) Growth 
of the Salmon in Fresh Water, Ann. and Mag. Nat. 
Hist., IV. p. 334. - Duvernoy, (G. L.,) Observa- 
tions pour servir a la connaissance du developpement 
de la Pecilie de Surinam, An. Sc. Nat., 1844, 3e ser. 
I. p. 313, fig.- Coste, (P.,) Histoire generale et 
particuliere du developpement des corps organises, 
Paris, 1847-53, 4to., Atl. fol., 2d Fasc., Epinoche.- 
Quatrefages, (Arm. de,) Memoire sur les Embry- 
ons des Syngnathes, Ann. Sc. Nat., 2de ser. vol. 18, 
p. 193, fig. - Sur le developpement embryonaire des 
Blennies, etc., Comptes-Rendus, vol. 17, p. 320.- 
Valenciennes, (A.,) Anableps in Cuvier et Valen- 
ciennes, Histoire naturelle des Poissons, Paris, 1846, 
vol. 18, p. 245. - Wyman, (J.,) Observations on the 
Development of Anableps Gronovii, Journ. Bost. Nat. 
Hist., 1854, vol. 6, fig. - Agassiz, (L.,) Extra- 
ordinary Fishes from California, constituting a new 
family, Amer. Journ. Sc. and A., 1853, vol. 16, p. 380. 
- Embryology of Lophius americanus, Proc. Am. Ac. 
1855. - Lereboullet, (A.,) Recherches sur 1'Ana- 
tomie des organes genitaux des animaux Vertebres, 
N. Act. Ac. Nat. Cur., vol. 23, p. 1. - Ann. Sc. Nat., 
4e ser. vol. 1. - Aubert, (H.,) Beitriige zur Ent- 
wickelungsgeschichte der Fische, Zeitsch. f. wiss. 
Zooh, 1853, vol. 5, p. 94; 1855, vol. 7. - Valen- 
tin, (G.,) Zur Entwickelungsgeschichte der Fische, 
Zeitsch. f. wiss. Zooh, 1850, vol. 2, p. 267. - Leuck- 
art, (R.,) Ueber die allmahlige Bildung der Korper- 
gestalt bei den Rochen, Zeitsch. f. wiss. Zooh, 1850, 
vol. 2, p. 258. - Haeckel, (E.,) Ueber die Eier der 
Scomberesoces, Miiller's Arch., 1855, p. 23.- Ret- 
zius, (A.,) Ueber den grossen Fetttropfen in den 
Eiern der Fische, Muller's Arch., 1855, p. 34.- 
Bruch, (C.,) Ueber die Micropyle der Fische, 
Zeitsch. f. wiss. Zooh, 1855, vol. 7, p. 172. - Rei- 
chert, (K. B.,) Ueber die Micropyle der Fischeier, 
etc., Muller's Arch., 1856, p. 83. - Dowler, (B.,) 
Discovery of a Viviparous Fish in Louisiana, Amer. 
Jour. Sc. and Arts, 1855, vol. 19, p. 133, with Remarks 
by L. Agassiz, p. 136.-Schultze, (M.,) Note sur le 
developpement des Petromyzons, Comptes-Rendus, 
1856, p. 336; Ann. and Mag. Nat. Hist., 2d ser. 82 
ESSAY ON CLASSIFICATION. 
Part I. 
The disagreement of authors as to the limits and respective value of its orders and 
families may be partly owing to the unnatural circumscription of the class itself.1 
As to the Reptiles, it is already certain, that the Amphibia and Reptiles proper, so 
long united as one class, constitute two distinct classes. In the main, the develop- 
ment of the true Reptiles2 agrees very closely with that of the Birds, while the 
Amphibians3 resemble more the true fishes. In no class are renewed embryological 
185G, vol. 17, p. 443. - Muller, (A.,) Ueber die 
Entwickelung der Neunaugen, Muller's Arch., 185G, 
p. 303. The unexpected facts mentioned here, render 
it highly probable, that Amphioxus is the immature 
state of some marine Cyclostoin. 
1 The peculiarities of the development of the 
Plagiostoms consist not so much in the few large 
eggs they produce, and the more intimate connection 
which the embryo of some of them assumes with the 
parent, than in the development itself, which, not- 
withstanding the absence of an amnios and an allan- 
tois, resembles closely, in its early stages, that of the 
Reptiles proper and of the Birds, especially in the 
formation of the vascular system, the presence of a 
sinus terminalis, etc. Again, besides the more ob- 
vious anatomical differences existing between the 
Plagiostoms and the bony Fishes, it should be remem- 
bered that, as in the higher Vertebrata, the ovary is 
separated from the oviducts in the Sharks and Skates, 
and the eggs are taken up by a wide fallopian tube. 
That the Plagiostoms can hardly be considered sim- 
ply as an order in the class of Fishes, could already 
be inferred from the fact, that they do not constitute 
a natural series with the other Fishes. I would, 
therefore, propose the name of Selachians for a 
distinct class embracing the Sharks, Skates, and 
Chimaeras. Recent investigations upon the Cyclos- 
toms, show them also to differ widely from the 
Fishes proper, and they too ought to be separated as 
a distinct class, for which the name of Myzontes 
may be most appropriate. 
2 Volkmann, (G. W.,) De Colubri Natricis 
Generatione, Lipsiae, 1834, 4to. - Rathke, (H.,) 
Entwickelungsgeschichte der Natter, (Coluber Na- 
trix,) Kbnigsberg, 1839, 4to. fig. - Weinland, (D.,) 
Ueber den Eizahn der Ringelnatter, Wiirt. Nat. 
Hist. Jahreshefte, 1855. - Tiedemann, (F.,) Ueber 
(las Ei und den Foetus der Schildkrbte, Heidelberg, 
1828, 4to. fig. - Baer, (K. E. v.,) Beitrage zur 
Entwickelungsgeschichte der Scliildkrbten, Muller's 
Archiv, 1834, p. 544.- Rathke, (II.,) Ueber die 
Entwickelung der Scliildkrbten, Braunschweig, 1848, 
4to. fig. 
8 Rosel v. Rosenhof, (A. J.,) Historia natu- 
ralis Ranarum nostratium, etc., Norinib., 1758, fol. 
fig. - F unk, (A. F.,) De Salamandrae terrestris vita, 
evolutione, formatione, etc., Berlin, 182G, fol. fig.- 
Rathke, (II.,) Diss, de Salamandrarum corporibus 
adiposis eorumque evolutione, Berol, 1818. - Ueber 
die Entstehung und Entwickelung der Geschlechts- 
theile bei den Urodelen, N. Schr., Dantz. Naturf. Ges., 
1820. - Steinheim, (L.,) Die Entwickelung der 
Frbsche, Hamburg, 1820, 8vo. fig. - Hasselt, (J. 
Conr., van,) Dissert, exhibens Observationes de 
metamorphosi quarumdam partium Ranae temporariae, 
Gbttingaa, 1820, 8vo. - Prevost, (J. L.,) et Lebert, 
Memoire sur la formation des organes de la circula- 
tion et du Sang dans les Batraciens, Ann. Sc. Nat., 3e 
ser. I. p. 193, fig. - Rusconi, (M.,) Developpement 
de la Grenouille commune, depuis le moment de sa 
naissance jusqu' a son etat parfait, Milan, 1828, 4to. 
fig. - Amours des Salamandres aquatiques et deve- 
loppement du Tetard de ces Salamandres, etc., Milan, 
1822, 4to. fig. - Baer, (K. E. v.,) Die Metamor- 
phose des Eies der Batrachier vor der Erscheinung 
des Embryo, etc., Muller's Archiv, 1834, p. 481. 
- Entwickelungsgeschichte, etc., vol. 2d, p. 280. - 
Reichert, (K. B.,) Das Entwickelungsleben im Wir- 
belthierreich, Berlin, 1840, 4to. fig. - Vergleichende 
Entwickelungsgeschichte des Kopfes der nackten 
Amphibien, etc., Kbnigsberg, 1838, 4to. fig. - Ueber 
den Furchungsprocess der Batrachier-Eier, Miiller's 
Archiv, 1841, p. 523. - Vogt, (C.,) Untersuchungen 
uber die Entwickelungsgeschichte der Geburtshelfer- Chap. I. 
METAMORPHOSES OF ANIMALS. 
83 
investigations, extending over a variety of families, so much needed, as in that of 
Birds, though the general development of these animals is, perhaps, better known 
than that of any other type;1 while the class of Mammalia2 has found in Bischoff 
a most successful and thorough investigator.3 
o o 
krbte, Solothurn, 1841, 4to. fig. - Quelques observa- 
tions sur 1'embryologie des Batraciens, Ann. Sc. n., 
3e ser. vol. 2, p. 45. - Remak, (R.,) Untersuchungen 
uber die Entwickelung der Wirbelthiere, Berlin, 1855, 
fol. - Newport, (G.,) On the Impregnation of the 
Ovum in the Amphibia, Philos. Trans. R. Soc., 1851, 
I., p. 169. - Wittich, (W. II. v.,) Beitriige zur mor- 
phologischen und histologischen Entwickelung der 
Harn- und Geschlechtswerkzeuge der nackten Amphi- 
bien, Zeitsch. f. wiss. Zool., 1852, vol. 4, p. 125.- 
Weinland, (D.,) Ueber den Beutelfrosch, Muller's 
Archiv, 1854, p. 449. - Wyman, (J.,) Observations 
on Pipa americana, Am. Jour. Sc. and Arts, 2d ser. 
1854, vol. 17, p. 369. 
1 Pander, (Chr. II.,) Diss, sistens historiam 
metamorphoseos quam ovum incubatum prioribus 
quinque diebus subit, Wirceb. 1817, 8vo. - Beitriige 
zur Entwickelungsgeschichte des Hiihnchens im Eie, 
Wiirzb. 1817, fol. fig. - Baer, (K. E. v.,) Entwicke- 
lungsgeschichte, etc., vol. 1. - Dutrochet, (II.,) 
Histoire de 1'oeuf des Oiseaux avant la ponte, Bull. 
Soc. Philom., 1819, p. 38. - Hunter, (John,) Obser- 
vations on Animal Development, edited and his Illus- 
trations of that process in the Bird described by R. 
Owen, London, 1841, fol. fig.- Prevost, (J. L.,) 
Memoire sur le developpement du poulet dans 1'ceuf, 
Ann. Sc. Nat., 1827, vol. 12, p. 415. - Prevost, (J. 
L.,) et Lebert, Memoires sur la formation des 
organes de la circulation et du sang dans 1'embryon 
du Poulet, Ann. Sc. Nat. 3e ser. I. p. 265 ; II. p. 222, 
fig.; III. p. 96. - Baudrimont, (A.,) et Martin St. 
Ange, (G. J.) Recherches anatomiques et physiolo- 
giques sur le developpement du foetus, Paris, 1850, 
4to. - Meckel v. Hemsbach, (II.,) Die Bildung der 
fur partielle Furchung bestimmten Eier der Vogel, 
etc., Zeitsch. f. wiss. Zool., 1852, vol. 3, p. 420. - 
In no class are embryological investigations extend- 
ing over a variety of families more needed than 
in that of Birds, if we should ever derive any 
assistance from the knowledge of their development 
for their natural classification. 
2 For the papers relating to the foetal envelopes 
and the placenta and also to the different systems 
of organs or any organ in particular and for human 
embryology generally, see Bischoff's article " Ent- 
wickelungsgeschichte," in R. Wagner's Handwbrter- 
buch der Physiologic, p. 867, where every thing that 
has been done in this direction, up to the year 1843, 
is enumerated. For more recent researches upon 
these topics consult, also, Muller's Archiv, Wieg- 
man's Archiv, Siebold und Kolliker's Zeitsch. 
f. wiss. Zool., Milne-Edwards, Ann. Sc. Nat., and 
the Annals and Magazine of Nat. Hist., etc. 
8 Bischoff, (Tn. L. W.,) Entwickelungsges- 
chichte des Kaninchen-Eies, Braunschweig, 1842, 
4to. fig. - Entwickelungsgeschichte des IIunde-Eies, 
Braunschweig, 1845, 4to. fig. - Entwickelungsges- 
chichte des Meerschweinchens, Giessen, 1852, 4to. fig. 
-Entwickelungsgeschichte des Rehes, Giessen, 1854, 
4to. fig. - Prevost, (J. L.,) et Dumas, (J. A.,) De 
la generation chez les Mammiferes, etc., Ann. Sc. Nat. 
1824, vol. 3, p. 113, fig. - Bojanus, (L.,) Observatio 
anatomica de fcctu canino 24 dierum, etc., Act. Ac. 
Nat. Cuv., vol. 10, p. 139, fig.-Coste, (P.,) Embry- 
ogenie comparee, Paris, 1837, 8vo. Atlas 4to. - His- 
toire particuliere et generale du developpement des 
corps organises, q. a. - Recherches sur le generation 
des Mammiferes et le developpement de la brebis, 
Ann. Sc. Nat., 1835, III. p. 78. - Recherches sur 
la generation des Mammiferes, Paris, 1834, 4to. fig. 
- Bernhardt, (C. A.,) Symbol® ad Ovi Mamma- 
lium historiam ante pregnationem, Vratish, 4to., Mul- 
ler's Arch., 1835, p. 228. - Barry, (M.,) Researches 
in Embryology," Phil. Trans. R. Soc. 1838, p. 301; 
1839, p. 307; 1840, p. 529; 1841, p. 195. -Baer, 
(H. E. v.,) q. a. - Owen, (R.,) On the Ova of 
the Ornithorhynchus paradoxus, Phil. Trans. 1834, 
p. 555. - On the Young of the Ornithorhynchus para- 84 
ESSAY ON CLASSIFICATION. 
Part I. 
Embryology has, however, a wider scope than to trace the growth of individual 
animals, the gradual building up of their body, the formation of their organs, and all 
the changes they undergo in their structure and in their form; it ought also to 
embrace a comparison of these forms and the successive steps of these changes 
between all the types of the animal kingdom, in order to furnish definite standards 
of their relative standing, of their affinities, of the correspondence of their organs in 
all their parts. Embryologists have thus far considered too exclusively, the gradual 
transformation of the egg into a perfect animal; there remains still a wide field of 
investigation to ascertain the different degrees of similarity between the successive 
forms an animal assumes until it has completed its growth, and the various forms of 
different kinds of full-grown animals of the same type; between the different stages 
of complication of their structure in general, and the perfect structure of their 
kindred; between the successive steps in the formation of all their parts and the 
various degrees of perfection of the parts of other groups; between the normal 
course of the whole development of one type compared with that of other types, as 
well as between the ultimate histological differences which all exhibit within certain 
limits. Though important fragments have been contributed upon these different 
points, I know how much remains to be done, from the little I have as yet been 
able to gather myself, by systematic research in this direction. 
I have satisfied myself long ago, that Embryology furnishes the most trustworthy 
standard to determine the relative rank among animals. A careful comparison of 
the successive stages of development of the higher Batrachians furnishes, perhaps, the 
most striking example of the importance of such investigations. The earlier stages 
of the Tadpole exemplify the structure and form of those Ichthyoids which have 
either no legs, or very imperfect legs, with and without external gills; next it 
assumes a shape reminding us more of the Tritons and Salamanders, and ends with 
the structure of the Frog or Toad.1 A comparison between the two latter families 
might prove further, that the Toads are higher than the Frogs, not only on account 
of their more terrestrial habits (see Sect. 16), but because the embryonic web, which, 
to some extent, still unites the fingers in the Frogs, disappears entirely in the Toads, 
and may be also, because glands are developed in their skin, which do not exist in 
Frogs. A similar comparison of the successive changes of a new species of Comatula 
discovered by Prof. Holmes, in the harbor of Charleston, in South Carolina, has 
shown me in what relation the different types of Crinoids of past ages stand to 
doxus, Trans. Zool. Soc., i. p. 221; Proc. Zodl. Soc., 
ii. p. 43; Ann. Sc. Nat., 2d ser. ii. p. 303; iii. 
p. 299. - On the Generation of the Marsupial Ani- 
mals, etc., Phil. Trans., 1824, p. 333. - Meigs, 
(Ch.,) Observations on the Reproductive Organs and 
on the Foetus of Delphinus Nesarnak, Journ. Ac. 
Nat. Sc. Phil., new ser. 1849, vol. 1, p. 267. 
1 Agassiz, (L.,) Twelve Lectures, etc., page 8. Chap. I. 
METAMORPHOSES OF ANIMALS. 
85 
these changes, and has furnished a standard to determine their relative rank; as 
it cannot be doubted, that the earlier stages of growth of an animal exhibit a 
condition of relative inferiority, when contrasted with what it grows to be, after 
it has completed its development, and before it enters upon those phases of its 
existence which constitute old age, and certain curious retrograde metamorphoses 
observed among parasites. 
In the young Comatula there exists a stem, by which the little animal is 
attached, either to sea weeds, or to the cirrhi of the parent; the stem is at first 
simple and without cirrhi, supporting a globular head, upon which the so-called arms 
are next developed and gradually completed by the appearance of branches; a few 
cirrhi are, at the same time, developed upon the stem, which increase in number 
until they form a wreath between the arms and the stem. At last, the crown 
having assumed all the characters of a diminutive Comatula, drops off, freeing itself 
from the stem, and the Comatula moves freely as an independent animal.1 
The classes of Crustacea and of Insects,2 are particularly instructive in this 
respect. Rathke, however, has described the transformations of so many Crustacea, 
that I cannot do better than to refer to his various papers upon this subject,3 for 
details relating to the changes these animals undergo during their earlier stages of 
growth. I would only add, that while the embryo of the highest Crustacea, the 
Brachyura, resembles by its form and structure the lowest types of this class, as the 
Entomostraca and Isopoda, it next assumes the shape of those of a higher order, 
the Macroura, before it appears with all the characteristics of the Brachyura. 
Embryology furnishes, also, the best measure of the true affinities existing 
between animals. I do not mean to say, that the affinities of animals can only be 
ascertained by embryonic investigations; the history of Zoology shows, on the con- 
trary, that even before the study of the formation and growth of animals had 
become a distinct branch of physiology, the general relationship of most animals had 
already been determined, with a remarkable degree of accuracy, by anatomical inves- 
tigations. It is, nevertheless, true, that in some remarkable instances, the knowledge 
of the embryonic changes of certain animals gave the first clue to their true affini- 
ties, while, in other cases, it has furnished a very welcome confirmation of relation- 
ships, which, before, could appear probable, but were still very problematical. Even 
Cuvier considered, for instance, the Barnacles as a distinct class, which he placed 
1 A condensed account of the transformations of 
the European Comatula, may be found in E. 
Forbes's History of-the British Starfishes, p. 10. 
The embryology of our species will be illustrated 
in one of my next volumes. 
2 See Agassiz's Twelve Lectures, p. 62, and 
Classification of Insects, etc., q. a. It is expected 
that Embryology may furnish the means of ascer- 
taining the relative standing of every family. 
8 See above, page 79, note 2. 86 
ESSAY ON CLASSIFICATION. 
Part I. 
among Mollusks, under the name of Cirripeds. It was not until Thompson1 had 
shown, what was soon confirmed by Burmeister and Martin St. Ange, that the 
young Barnacle has a structure and form identical with that of some of the most 
common Entomostraca, that their true position in the system of animals could be 
determined; when they had to be removed to the class of Crustacea, among Articu- 
lata. The same was the case with the Lermeans, which Cuvier arranged with the 
Intestinal Worms, and which Nordmann has shown upon embryological evidence to 
belong also to the class of Crustacea.2 Lamarck associated the Crinoids with Polypi, 
and though they were removed to the class of Echinoderms by Cuvier, before the 
metamorphoses of the Comatula were known,3 the discovery of their pedunculated 
young furnished a direct proof that this was their true position. 
Embryology affords further a test for homologies in contradistinction of analogies. 
It shows that true homologies are limited respectively within the natural boundaries 
of the great branches of the animal kingdom. 
The distinction between homologies and analogies, upon which the English natu- 
ralists have first insisted,4 has removed much doubt respecting the real affinities of 
animals which could hardly have been so distinctly appreciated before. It has 
taught us to distinguish between real affinity, based upon structural conformity, and 
similarity, based upon mere external resemblance in form and habits. But even after 
this distinction had been fairly established, it remained to determine within what 
limits homologies may be traced. The works of Oken, Spix, Geoffroy, and Carus,5 
show to what extravagant comparisons a preconceived idea of unity may lead. It 
was not until Baer had shown that the development of the four great branches of 
the animal kingdom is essentially different,6 that it could even be suspected that 
organs performing identical functions may be different in their essential relations to 
one another, and not until Rathke7 had demonstrated that the yolk is in open 
communication with the main cavity of the Articulata, on the dorsal side of the 
animal, and not on the ventral side, as in Vertebrata, that a solid basis was ob- 
tained for the natural limitation of true homologies. It now appears more and 
more distinctly, with every step of the progress Embryology is making, that the 
structure of animals is only homologous within the limits of the four great branches 
1 Thompson's Zool. Researches, etc.; Burmeis- 
ter's Beitriige, etc.; Martin St. Ange, Mem. sur 
1'organisation, etc., quoted above, page 79, note 1. 
2 Nordmann's Micrographische Beytnige, q. a. 
8 Thompson and Forbes, q. a., page 79. 
4 Swainson's Geography and Classification, etc. 
See above, Sect. V., p. 20. 
5 See, above, Sect. IV., notes 1 and 2. 
6 Baer's Entwickelungsgeschichte, vol. 1, p. 160 
and 224. The extent of Baer's information and the 
comprehensiveness of his views, nowhere appear so 
strikingly as in this part of his work. 
7 Rathke's Unters. uber Bild., etc., see, above, p. 
79, note 2. Chap. I. 
METAMORPHOSES OF ANIMALS 
87 
of the animal kingdom, and that general homology strictly proved, proves also 
typical identity, as special homology proves class identity. 
The results of all embryonic investigations of modern times go to show more 
and more extensively, that animals are entirely independent of external causes in 
their development. The identity of the metamorphoses of oviparous and viviparous 
animals belonging to the same type, furnishes the most convincing evidence to that 
effect.1 Formerly it was supposed that the embryo could be affected directly by 
external influences to such an extent, that monstrosities, for instance, were ascribed to 
the influence of external causes. Direct observation has shown, that they are 
founded upon peculiarities of the normal course of their development.2 The snug 
berth in which the young undergo their first transformation in the womb of their 
mother in all Mammalia, excludes so completely the immediate influence of any 
external agent, that it is only necessary to allude to it, to show how independent 
their growth must be of the circumstances in which even the mother may be placed. 
This is equally true of all other viviparous animals, as certain snakes, certain sharks, 
and the viviparous fishes. Again, the uniformity of temperature in the nests of birds, 
and the exclusion, to a certain degree, of influences which might otherwise reach 
them, in the various structures animals build for the protection of their young or of 
their eggs,3 show distinctly, that the instinct of all animals leads them to remove 
their progeny from the influence of physical agencies, or to make these agents sub- 
servient to their purposes, as in the case of the ostrich. Reptiles and terrestrial 
Mollusks bury their eggs to subtract them from varying influences; fishes deposit 
them in localities where they are exposed to the least changes. Insects secure theirs 
1 This seems the-most appropriate place to re- 
mark, that the distinction made between viviparous 
and oviparous animals is not only untenable as far as 
their first origin in the egg is concerned, but also un- 
physiological, if it is intended, by this designation, to 
convey the idea of any affinity or resemblance in their 
respective modes of development. Fishes show more 
distinctly than any other class, that animals, the devel- 
opment of which is identical, in all its leading feat- 
ures, may either be viviparous or oviparous; the dif- 
ference here arising only from the connection in 
which the egg is developed, and not from the devel- 
opment itself. Again, viviparous and oviparous ani- 
mals of different classes, differ greatly in their devel- 
opment, even though they may agree in laying eggs 
or bringing forth living young. The essential feature 
upon which any important generalization may be 
based, is, of course, the mode of development of the 
germ. In this respect we find that Selachians, whe- 
ther oviparous or viviparous, agree with one another; 
this is also the case with the bony fishes and the rep- 
tiles, whether they are respectively oviparous or vivi- 
parous ; even the placentalian and non-placentalian 
Mammalia agree with one another in what is essential 
in their development. Too much importance has thus 
far been attached to the connections in which the germ 
is developed, to the exclusion of the leading features 
of the transformations of the germ itself. 
2 Bishoff, (Th. L. W.,) in R. Wagner's Hand- 
wbrterbuch der Physiologic, Article " Entwickelungs- 
geschichte," p. 885. 
3 Burdach's Physiologic, etc., q. a. vol. 2, 2d ed. 
Sect. 334-38. See, also, Kirby and Spence's Intro- 
duction, etc., q. a. 88 
ESSAY ON CLASSIFICATION. 
Part I. 
in various ways. Most marine animals living in extreme climates, lay their eggs in 
winter, when the variations of external influences are reduced to a minimum. 
Everywhere we find evidence that the phenomena of life, though manifested in the 
midst of all the most diversified physical influences, are rendered independent of 
them to the utmost degree, by a variety of contrivances prepared by the animals 
themselves, in self-protection, or for the protection of their progeny from any influ- 
ence of physical agents not desired by them, or not subservient to their own ends. 
SECTION XIX. 
DURATION OF LIFE. 
There is the most extraordinary inequality in the average duration of the life of 
different kinds of animals and plants. While some grow and reproduce themselves 
and die in a short summer, nay, in a day, others seem to defy the influence of 
time.1 
Who has thus apportioned the life of all organized beings ? To answer this 
question, let us first look at the facts of the case. In the first place, there is no 
conformity between the duration of life and either the size, or structure, or habitat 
of animals; next, the system, in which the changes occurring during any period are 
regulated, differs in almost every species, there being only a slight degree of uni- 
formity between the representatives of different classes, within certain limits. 
In most Fishes and the Reptiles proper, for instance, the growth is very gradual 
and uniform, and their development continues through life, so much so that their 
size is continually increasing with age. 
In others, the Birds, for instance, the growth is rapid during the first period of 
their life, until they have acquired their full size, and then follows a period of equi- 
librium, which lasts for a longer or shorter period in different species. 
In others still, which also acquire within certain limits a definite size, the Mam- 
malia, for instance, the growth is slower in early life, and maturity is attained, as in 
man, at an age which forms a much longer part of the whole duration of life. 
In Insects, the period of maturity is, on the contrary, generally the shortest, 
while the growth of the larva may be very slow, or, at least, that stage of develop- 
ment last for a much longer time than the life of the perfect Insects. There is no 
1 Schubler, (Gust.,) Beobachtungen uber ja.hr- 
liche periodisch wiederkehrende Erscheinungen ini 
Thier- und Pflanzenreich, Tubingen, 1831, 8vo.- 
Quetelet, (A.,) Phenomenes periodiques, Ac. Brux. Chap. I. 
DURATION OF LIFE. 
89 
more striking example of this peculiar mode of growth than the seventeen years 
locust, so fully traced by Miss M. H. Morris.1 
While all longlived animals continue, as a matter of course, their existence 
through a series of years, under the varying influence of successive seasons, there 
are many others which are periodical in their appearance; this is the case with most 
insects,2 but perhaps in a still more striking manner with Medusae.3 
The most interesting point in this subject is yet the change of character which 
takes place in the different stages of growth of one and the same animal. Neither 
Vertebrata, nor Mollusks, nor even Radiata exhibit in this respect any thing so 
remarkable in the continuous changes which an individual animal may undergo, as 
the Insects, and among them those with so-called complete metamorphoses, in which 
the young (the larva) may be an active, wormlike, voracious, even carnivorous 
being, which in middle life (the chrysalis) becomes a mummylike, almost motionless 
maggot, incapable of taking food, ending life as a winged and active insect. Some 
of these larvae may be aquatic and very voracious, when the perfect insect is aerial 
and takes no food at all.4 
Is there any thing in this regulation of the duration of life in animals which 
recalls the agency of physical forces ? Does not, on the contrary, the fact, that 
while some animals are periodical and bound to the seasons in their appearance, 
and others are independent of the course of the year, show distinctly their independ- 
ence of all those influences which, under a common expression, are called physical 
causes ? Is this not further illustrated in the most startling manner by the extraor- 
dinary changes, above alluded to, which one and the same animal may undergo 
during different periods of its life? Does this not prove directly the immediate 
intervention of a power capable of controlling all these external influences, as well 
as regulating the course of life of every being, and establishing it upon such an 
immutable foundation, within its cycle of changes, that the uninterrupted action of 
these agents shall not interfere with the regular order of their natural existence? 
There is, however, still another conclusion to be drawn from these facts: they 
point distinctly at a discriminating knowledge of time and space, at an appreciation 
of the relative value of unequal amounts of time and an unequal repartition of 
small, unequal periods over longer periods, which can only be the attribute of a 
thinking being. 
1 Harris's Insects injurious to Vegetation, p. 184. 
2 Herold, (E.,) Teutscher Raupen-Kalender, 
Nordhausen, 1845. 
3 Agassiz's Acalephs of North America, p. 228. 
4 Burmeister's Handb. d. Entom. etc. - Lacor- 
daire, Introd, a 1'Entomologie, etc. - Kirby and 
Spence, Introd, to Entomol., etc., q. a., give accounts 
of the habits of Insects during their metamorphosis. 90 
ESSAY ON CLASSIFICATION. 
Part L 
SECTION XX. 
ALTERNATE GENERATIONS. 
While some animals go on developing gradually from the first formation of their 
germ to the natural end of their life, and bring forth generation after generation, a 
progeny which runs with never varying regularity through the same course, there 
are others which multiply in various ways, by division and by budding,1 or by a 
strange succession of generations, differing one from the other, and not returning, by 
a direct course, to their typical cycle. 
The facts which have led to the knowledge of the phenomena now generally 
known under the name of alternate generation, were first observed by Chamisso and 
Sars, and afterwards presented in a methodical connection by Steenstrup, in his 
famous pamphlet on that subject.2 As a brief account of the facts may be found in 
almost every text-book of Physiology, I need not repeat them here, but only refer 
to the original investigations, in which all the details known upon this subject may 
be found.3 These facts show, in the first place with regard to Hydroid Medusae, that 
the individuals born from eggs, may be entirely different from those which produced 
the eggs, and end their life without ever undergoing themselves such changes as 
would transform them into individuals similar to their parents;4 they show further, 
1 Much information useful to the zoologist, may 
be gathered from Braun's paper upon the Budding 
of Plants, q. a., p. 18, note 3. The process of multi- 
plication by budding or by division, and that of sexual 
reproduction, are too often confounded by zoologists, 
and this confusion has already led to serious mis- 
constructions of well known facts. 
2 Steenstrup, (J.,) Ueber den Generationswech- 
sel, q. a., p. 69, note 3. 
8 See the works quoted above, page 69, note 3, 
and p. 70, note 1, also Carus, (V.,) Zur nahern Kennt- 
niss des Generationswechsels, Leipzig, 1849, 8vo.- 
Einige Worte uber Metamorphose und Generations- 
wechsel, Zeitsch. f. wiss. Zool., 1851, vol. 3, p. 359. 
- Owen, (R.,) On Parthenogenesis, or the Succes- 
sive Production of Procreating Individuals from a 
single Ovum, London, 1849, 8vo. - On Metamor- 
phosis and Metagenesis, Ann. and Mag. Nat. Hist., 
2d ser. vol. 8, 1857, p. 59. - Prosch, (V.,) Om 
Parthenogenesis og Generationsvexel et Bidrag til 
Generationslaeren, Kidbenhavn, 1851. - Leuckart, 
(R.,) Ueber Metamorphose, ungeschlechtliche Ver- 
mehrung, Generationswechsel, Zeitsch. f. wiss. Zool„ 
vol. 3, 1851. - Dana, (J. D.,) On the Analogy 
between the Mode of Reproduction in Plants and the 
" Alternation of Generations " observed in some 
Radiata, Amer. Journ. A. and Sc., 2d ser. vol. 10, 
p. 341. - Ehrenberg, (C. G.,) Ueber die Formen- 
bestandigkeit und den Entwickelungskreis der orga- 
nischen Formen, Monatsber. der Akad., Berlin, 1852, 
8vo. 
4 Polymorphism among individuals of the same 
species is not limited to Acalephs ; it is also observed 
among genuine Polyps, the Madrepores, for example, 
and among Bryozoa, Ascidians, Worms, Crustacea 
(Lupea), and even among Insects (Bees). Chap. I. 
ALTERNATE GENERATIONS. 
91 
that this brood originating from eggs, may increase and multiply by producing new 
individuals like themselves (Syncoryne), or of two kinds (Campanularia), or even indi- 
viduals of various kinds, differing all to a remarkable extent, one from the other, 
(Hydractinia,) but in neither case resembling their common parent. None of these 
new individuals have distinct reproductive organs, any more than the first indi- 
viduals born from eggs, their multiplication taking place chiefly by the process of 
budding; but as these buds remain generally connected with the first individual 
born from an egg, they form compound communities, similar to some polypstocks. 
Now some of these buds produce, at certain seasons, new buds of an entirely differ- 
ent kind, which generally drop off from the parent stock, at an early period of their 
development, (as in Syncoryna, Campanularia, etc.,) and then undergo a succession of 
changes, which end by their assuming the character of the previous egg-laying 
individuals, organs of reproduction of the two sexes developing meanwhile in them, 
which, when mature, lead to the production of new eggs; in others (as in Hydrac- 
tinia,) the buds of this kind do not drop off, but fade away upon the parent stock, 
after having undergone all their transformations, and also produced in due time, a 
number of eggs.1 
Oo 
In the case of the Medusae proper,2 the parent lays eggs, from which originate 
polyplike individuals; but here these individuals divide by transverse constrictions 
into a number of disks, every one of which undergoes a succession of changes, which 
end in the production of as many individuals, each identical with the parent, and 
capable in its turn, of laying eggs, (some, however, being males and others females.) 
But the polyplike individuals born from eggs may also multiply by budding and 
each bud undergo the same changes as the first, the base of which does not die, but 
is also capable of growing up again and of repeating the same process. 
In other classes other phenomena of a similar character have been observed, 
which bear a similar explanation. J. Muller3 has most fully illustrated the alter- 
nate generations of the Echinoderms; Chamisso, Steenstrup, Eschricht, Krohn, and 
Sars, those of the Salpae;4 von Siebold, Steenstrup, and others, those of certain Intes- 
tinal Worms.6 
This alternate generation differs essentially from metamorphosis, though some 
1 I have observed many other combinations of a 
similar character among the Hydroid Medusae, which 
I shall describe at full length in my second volume; 
and to which I do not allude here, as they could not 
be understood without numerous drawings. The 
case of Hydractinia is not quite correctly repre- 
sented in the works in which that animal has been 
described. Respecting Physalia and the other 
Siphonophora, see the works quoted above, p. 69, 
note 3. 
2 See Siebold, and Sars, q. a., p. 69, note 3. 
3 Muller, (J.,) Ueber den allgemeinen Plan, 
etc., q. a., p. 70, note 1. 
4 See the works, q. a., page 72, note 4. 
5 See the works, q. a., page 76, note 2, and 77, 
note 1. 92 
ESSAY ON CLASSIFICATION. 
Part I. 
writers have attempted to identify these two processes. In metamorphosis, as 
observed among Insects, the individual born from an egg goes on undergoing change 
after change, in direct and immediate succession, until it has reached its final trans- 
formation ; but however different it may be at different periods of its life, it is 
always one and the same individual. In alternate generations, the individual born 
from an egg never assumes through a succession of transformations the character of 
its parent, but produces, either by internal or external budding or by division, a 
number, sometimes even a large number of new individuals, and it is this progeny 
of the individuals born from eggs, which grows to assume again the characters of 
the egg-laying individuals. 
There is really an essential difference between the sexual reproduction of most 
animals, and the multiplication of individuals in other ways. In ordinary sexual 
reproduction, every new individual arises from an egg, and by a regular succession 
of changes assumes the character of its parents. Now, though all species of animals 
reproduce their kind by eggs, and though in each there is at least a certain number 
of individuals, if not all, which have sprung from eggs, this mode of reproduction is 
not the only one observed among animals. We have already seen how new individ- 
uals may originate from buds, which in their turn may produce sexual individuals; 
we have also seen how, by division, individuals may also produce other individuals 
differing from themselves quite as much as the sexual buds, alluded to above, may 
differ from the individuals which produce them. There are yet, still other com- 
binations in the animal kingdom. In Polyps, for instance, every bud, whether it 
is freed from the parent stock or not, grows at once up to be a new sexual 
individual; while in many animals which multiply by division, every new individual 
thus produced assumes at once the characters of those born from eggs.1 There 
is, finally, one mode of reproduction which is peculiar to certain Insects, in which 
several generations of fertile females follow one another, before males appear again.2 
What comprehensive views the physical agents must be capable of taking, and 
what a power of combination they must possess, to be able to ingraft all these 
complicated modes of reproduction upon structures already so complicated! - But 
if we turn away from mere fancies and consider the wonderful phenomena just 
alluded to, in all their bearings, how instructive they appear with reference to this 
very question of the influence of physical agents upon organized beings! For here 
we have animals endowed with the power of multiplying in the most extraordinary 
ways, every species producing new individuals of its own kind, differing to the utmost 
from their parents. Does this not seem, at first, as if we had before us a perfect 
1 Milne-Edwards, Rech. anat. et zool. faites pen- 
dant un Voyage sur les cotes de Sicile, 3 vols. 4to. tig. 
2 Owen, Parthenogenesis, etc., q. a., p. 90.-Bon- 
net, (Ch.,) Traite d'Insectologie, etc., Paris, 1745. Chap. I. 
SUCCESSION OF ANIMALS AND PLANTS. 
93 
exemplification of the manner in which different species of animals may originate, one 
from the other, and increase the number of types existing at first? And yet, with all 
this apparent freedom of transformation, what do the facts finally show ? That all 
these transformations are the successive terms of a cycle, as definitely closed within 
precise limits, as in the case of animals, the progeny of which resembles for ever 
the immediate parent, in all successive generations. For here, as everywhere in 
the organic kingdoms, these variations are only the successive expressions of a 
well regulated cycle, ever returning to its own type. 
SECTION XXI. 
SUCCESSION OF ANIMALS AND PLANTS IN GEOLOGICAL TIMES. 
Geologists hardly seem to appreciate fully, the whole extent of the intricate 
relations exhibited by the animals and plants whose remains are found in the 
different successive geological formations. I do not mean to say, that the investi- 
gations we possess respecting the zoological and botanical characters of these remains 
are not remarkable for the accuracy and for the ingenuity with which they have 
been traced. On the contrary, having myself thus far devoted the better part of 
my life to the investigation of fossil remains, I have learned early, from the difficul- 
ties inherent in the subject, better to appreciate the wonderful skill, the high 
intellectual powers, the vast erudition displayed in the investigations of Cuvier 
and his successors upon the faunae and florae of past ages.1 But I cannot refrain 
1 Cuvier, (G.,) Recherches sur les Ossemens 
fossiles de Quadrupedes, etc., Paris, 1812, 4 vols. 
4to.; nouv. edit. Paris, 1821-23, 5 vols. 4to.; 4e 
edit. 10 vols. 8vo. and 2 vols. pl. 4to. - Sowerby, 
(James,) The Mineral Conchology of Great Britain, 
London, 1812-19, 6 vols. 8vo. fig. - Schlottheim, 
(E. F. v.,) Die Petrefactenkunde, etc., Gotha, 1820, 
8vo. fig. - Lamarck, (J. B. de,) Memoires sur les 
fossiles des environs de Paris, Paris, 1823, 4to. fig.- 
Goldfuss, (G. A.,) Petrefacta Germanise, Diissel- 
dorf, 1826-33, fol. fig. - Sternberg, (Kaspar, M. 
Gr. v.,) Versuch einer geognostisch-botanischen Dar- 
stellung der Flora der Vorwelt, Leipzig und Prag, 
1820-38, fol. fig. - Brongniart, (Ad.,) Prodrome 
d'une Histoire des Vegetaux fossiles, Paris, 1818, 
2 vols. 8vo. - Histoire des Vegetaux fossiles, Paris, 
1828-43, 2 vols. 4to. fig. - Lindley, (J.,) and Hut- 
ton, (W.,) The Fossil Flora of Great Britain, Lon- 
don, 1831-37, 3 vols. 8vo. - Goppert, (H. R.,) 
Systema Filicum fossilium, Vratisl. et Bonn®, 1836, 
4to. fig. - Die Gattungen der fossilen Pflanzen, ver- 
glichen mit denen der Jetztwelt, etc., Bonn, 1841- 
48, 4to. fig. - Monographic der fossilen Coniferen. 
Dusseldorf, 1850, 4to. fig. - More special works are 
quoted hereafter, but only such works shall be men- 
tioned, which have led on, in the progress of Geology 
and Palaeontology, or contain full reports of the pres- 
ent state of our science, and also such as have 
special reference to America. References to the 
description of species may be found in Bronn, 94 
ESSAY ON CLASSIFICATION. 
Part I. 
from expressing my wonder at the puerility of the discussions in which some geol- 
ogists allow themselves still to indulge, in the face of such a vast amount of well 
digested facts as our science now possesses. They have hardly yet learned to see 
that there exists a definite order in the succession of these innumerable extinct 
beings; and of the relations of this gradation to the other great features exhibited 
by the animal kingdom, of the great fact, that the development of life is the promi- 
nent trait in the history of our globe,1 they seem either to know nothing, or to 
look upon it only as a vague speculation, plausible perhaps, but hardly deserving 
the notice of sober science. 
It is true, Palmontology as a science is very young; it has had to fight its 
course through the unrelenting opposition of ignorance and prejudice. What amount 
of labor and patience it has cost only to establish the fact, that fossils are really 
the remains of animals and plants that once actually lived upon earth,2 only those 
know, who are familiar with the history of science. Then it had to be proved, 
that they are not the wrecks of the Mosaic deluge, which, for a time, was the 
prevailing opinion, even among scientific men.3 After Cuvier had shown, beyond 
question, that they are the remains of animals no longer to be found upon earth, 
among the living, Palaeontology acquired for the first time a solid basis. Yet what 
an amount of labor it has cost to ascertain, by direct evidence, how these remains 
are distributed in the solid crust of our globe, what are the differences they exhibit 
in successive formations,4 what is their geographical distribution, only those can 
(II. G.,) Index palaeontologicus, Stuttgart, 1848-49, 
3 vols. 8vo. - See also, Keferstein, (Chr.,) Ge- 
schichte und Literatur der Geognosie, Halle, 1840, 
1 vol. 8vo. - Archiac, (Vic. d',) Ilistoire des pro- 
gres de la Geologic, Paris, 1847, et suiv, 4 vols. 
8vo.; and the Transactions, Journals, and Proceed- 
ings of the Geological Society of London, of Paris, 
of Berlin, of Vienna, etc.; also, Leonhard and 
Bronn's Neues Jahrbuch, etc. 
1 Agassiz's Geological Times, etc., q. a., p. 25, 
note 2. - Dana's Address to the Amer. Ass. for Adv. 
Sc. 8th Meeting, held at Providence, 1855. 
2 Scilla, (Ag.,) La vana speculazione desin- 
gannata dal senso. Napoli, 1G70, 4to. fig. 
8 Sciieuciizer, (J. J.,) Homo Diluvii testis et 
IhwxoTro?, Tiguri, 172G, 4to. - Buckland, (W.,) 
Reliquiae diluvianae, or Observations on the Organic 
Remains attesting the Action of an Universal Deluge, 
London, 1826, 4to. fig. 
4 For references respecting the fossils of the 
oldest geological formations, see the works, quoted 
above, p. 23, note 1. Also, McCoy, (F.,) Synopsis 
of the Silurian Fossils of Ireland, Dublin, 1846, 4to. 
fig. - Geinitz, (H. D.,) Die Versteinerungen der 
Grauwackenformation, Leipzig, 1850-53, 4to. fig.- 
And for local information, the geological reports of 
the different States of the Union, a complete list of 
which, with a summary of the Geology, may be found 
in Marcou's (J.,) Rdsume explicatif d'une carte 
geologique des Etats-Unis, Bull. Soc. Geol. de 
France, Paris, 1855, 2de ser. vol. 12. - For the 
Devonian system: Phillips, (John,) Figures and 
Descriptions of the Palaeozoic Fossils of Cornwall, 
Devon, and Westsomerset, etc., London, 1841, 8vo.- 
Archiac, (Vic. d',) and Verneuil, (Ed. de,) Me- 
moir on the Fossils of the Older Deposits in the 
Rhenish Provinces, Paris, 1842, 4to. fig. - Sand- 
berger, (G. und Fr.,) Systematische Beschreibung Chap. I. 
SUCCESSION OF ANIMALS AND PLANTS. 
95 
fully appreciate, who have had a hand in the work.1 And even now, how many 
important questions still await an answer! 
und Abbildung der Versteinerungen des Rheinischen 
Schichtensystems in Nassau, Wiesbaden, 1850-54, 
4to. fig. - For the Carboniferous period: Phillips, 
(J.,) Illustrations of the Geology of Yorkshire, Lon- 
don, 1836, 2d vol., 4to. fig. - DeKoninck, (L.,) 
Descriptions des animaux fossiles qui se trouvent 
dans le terrain houiller de la Belgique, Liege, 1842, 
2 vols. 4to. fig.; suppl., etc. - McCoy, (Fr.,) Synop- 
sis of the Carboniferous Fossils of Ireland, Dublin, 
1844, 4to. fig. - Germar, (E. Fr.,) Die Versteine- 
rungen des Steinkohlengebirges, Halle, 1844-53, 
fol. fig. - Geinitz, (H. B.,) Die Versteinerungen 
der Steinkohlenformation, Leipzig, 1855, fol. fig. - 
For the Permian system: Quenstedt, (A.,) Ueber 
die Identitat der Petrificate des Thiiringischen und 
Englischen Zechsteins, Wiegman's Archiv, 1835, I., 
p. 75. - Geinitz, (II. B.,) und Gutbier, (A.,) Die 
Versteinerungen des Zechsteingebirges, etc., Dres- 
den, 1849, 4to. fig. - King, (W.,) Monograph of 
the Permian Fossils of England, (Palaeont. Soc.,) 
London, 1850, 4to. fig. - For the Triasic system: 
Alberti, (Fr. v.,) Beitrag zur einer Monographic 
des bunten Sandsteins, Mushelkalks, und Keupers, 
Stuttgart und Tubingen, 1834, 8vo. - For the Jura, 
Phillips, (J.,) Illustrations of the Geology of York- 
shire, York, 1829, vol. 1, 4to. fig. - Pusch, (G. G.,) 
Polens Palaeontologie, etc., Stuttgart, 1836, 4to. fig.- 
Romer, (Fr. A.,) Die Versteinerungen des nord- 
deutsehen Oolithen-Gebirges, Hannover, 1836, 4to. 
fig. - Zieten, (C. II. v.,) Die Versteinerungen Wiir- 
tembergs, Stuttgart, 1830-34, fol. fig.-Oribgny, 
(Alc. d',) Paleontologie fran^aise, Paris, 1840-53, 
8vo. fig. - Morris, (J.,) and Lycett, (J.,) Mollusca 
from the Great Oolite, (Palaeont. Soc.,) London, 
1850-55, 4to. fig. - For the Cretaceous period: Mor- 
ton, (S. G.,) Synopsis of the Remains of the Creta- 
ceous Group of the United States, Philadelphia, 1834, 
8vo. fig. - Orbigny, (Alc. d',) Paleont. frang., q. a. 
- Geinitz, (H. Br.,) Charakteristik der Schichten 
und Petrefakten des Kreidegebirges, Dresden, 1839- 
42, 4to. fig. - Pictet, (F. J.,) et Roux, (W.,) 
Description des fossiles qui se trouvent dans les gres 
verts des environs de Geneve, Mem. Soc. Phys., etc., 
Geneve, 1847-52, vol. 12 et 13. - Romer, (F. A.,) 
Die Versteinerungen des norddeutschen Kreidege- 
birges, Hannover, 1841, 4to. fig. - Die Kreide- 
bildungen von Texas, Bonn, 1852, 4to. fig. - Reuss, 
(A. E.,) Die Versteinerungen der bbhmischen Kreide- 
formation, Stuttgart, 1845-46, 4to. fig. - Muller, 
(Jos.,) Monographic der Petrefacten der Aachener 
Kreideformation, Bonn, 1851, 4to. fig. - Sharpe, 
(D.,) Fossil Remains of Mollusca found in the Chalk 
of England, (Palaeont. Soc.,) London, 1854, 4to. fig.- 
Hall, (James,) Cretaceous Fossils of Nebraska, 
Trans. Amer. Acad., 1856, vol. 5. - For the Ter- 
tiaries: Brocchi, (G. B.,) Conchiologia fossile sub- 
appennina, etc., Milano, 1814-43, 2 vols., 4to. fig.- 
DesHayes, (G. P.,) Description des coquilles fossiles 
des environs de Paris, 1824-37, 3 vols. 4to. Atl. - 
Bronn, (II. G.,) Italiens Tertiargebilde, Heidelberg, 
1831, 8vo. - Lea, (I.,) Contributions to Geology, 
Philadelphia, 1833, 8vo. fig. - Conrad, (T. A.) 
Fossil Shells of the Tertiary Formations of North 
America, Philadelphia, 1832-36, 8vo. fig.- Grate- 
LOUP, (Dr.,) Conchyliologie fossile du bassin de 
1'Adour, etc., Bordeaux, 1837, 8vo. fig. - Matheron, 
(Ph.,) Catalogue methodique et descriptif des corps 
organises fossiles, etc., Marseilles, 1842, 8vo. - 
Berendt, (G. C.,) Organische Reste im Bernstein, 
Berlin, 1845-54, fol. fig. -Wood, (S. V.,) A 
Monograph of the Crag Mollusks, (Palaeont. Soc.,) 
1848-50, 4to. fig. - Edwards, (F. E.,) Eocene 
Mollusca, (Palaeont. Soc.,) London, 1849-52, 4to. fig. 
- Horness, (M.,) Die fossilen Mollusken des Ter- 
tiiir-Beckens von Wien, Wien, 1851, 4to. fig. - 
Beyrich, (E.,) Die Conchylien des norddeutschen 
Tertiargebirges, Berlin, 1854-56, 8vo. fig. - Tuo- 
mey, (M.,) and Holmes, (Fr. S.,) Fossils of South 
Carolina, Charleston, 1855-56, 4to. fig. 
1 Buch, (L. v.,) Petrifications recueillies en 
Amerique par Mr. Alex, de Humboldt et par Mr. 
Ch. Degenhard, Berlin, 1838, fol. fig. - Orbigny, 
(Alc. d',) Voyage dans 1'Amerique Meridionale, etc., 
Paris, 1834-43, 7 vols. 8vo. Atl. 4to. - Archiac, 96 
ESSAY ON CLASSIFICATION. 
Part I. 
One result, however, stands now unquestioned: the existence during each great 
geological era1 of an assemblage of animals and plants differing essentially for each 
period. And by period I mean those minor subdivisions in the successive sets 
of beds of rocks, which constitute the stratified crust of our globe, the number of 
which is daily increasing, as our investigations become more extensive and more 
precise.2 What remains to be done, is to ascertain with more and more precision, 
the true affinities of these remains to the animals and plants now living, the rela- 
tions of those of the same period to one another, and to those of the preceding 
and following epochs, the precise limits of these great eras in the development 
of life, the character of the successive changes the animal kingdom has undergone, 
the special order of succession of the representatives of each class,3 their combina- 
(Vic. d',) et Haime, (J.,) Description des animaux 
fossiles du groupe nummulitique de 1'Inde, Paris, 
1853, 4to. fig. - Leuckart, (F. S.,) Ueber die 
Verbreitung der iibriggebliebenen Reste einer vor- 
weltlichen Schopfung, Freiburg, 1835, 4to. 
1 Geological text-books: DelaBeche, (Sir II.T.,) 
Geological Manual, London, 1833, 1 vol. 8vo.; Ger- 
man Trans, by Dechen ; French by Brochant de Vil- 
lers.- The Geological Observer, London, 1851, 8vo. 
- Lyell, (Sir C.,) Manual of Elementary Geology, 
London, 1851, 1 vol. 8vo. - Principles of Geology, 
etc., London, 1830, 2 vols. 8vo.; 8th edit., 1850, 
1 vol. 8vo. - Naumann, (C. Fr.,) Lehrbuch der 
Geognosic, Leipzig, 1850-54, 2 vols. 8vo. Atl. 4to.- 
Vogt, (C.,) Lehrbuch der Geologic und Petrefakten- 
kunde, Braunschweig, 1854, 8vo. 2 vols., 2d edit.- 
Text-books on Fossils: Bronn, (II. G.,) Lethaea 
Geognostica, Stuttgart, 1835-37, 2 vols., 8vo. Atl. 
fol.; 3d edit, with Fr. Riemer, 1846, et seq. - 
Pictet, (F. J.,) Traite elementaire de Paleontologie, 
etc., Paris, 1844-45, 4 vols., 8vo. fig.; 2de edit. 1853 
et seq., 8vo. Atl. 4to. - Orbigny, (Alc. d',) Cours 
elementaire de Paleontologie, Paris, 1852, 3 vols., 
12mo. - Giebel, (E. G.,) Fauna der Vorwelt, Leip- 
zig, 1852, 2 vols. 8vo. - Allgemeine Paheontologie, 
Leipzig, 1852, 1 vol., 8vo. - Quenstedt, (F. A.,) 
Handbuch der Petrefaktenkunde, Tubingen, 1852, 
8vo. fig. Unfortunately, there exists not a single 
English text-book of Palaeontology. A translation 
of Pictet's and Broun's works would be particularly 
desirable. 
2 At first, only three great periods were distin- 
guished, the primary, the secondary, and the tertiary; 
afterwards, six or seven, (DelaBeche) ; later, from 
ten to twelve; now, the number is almost indefinite, 
at least undetermined in the present stage of our 
knowledge, when many geologists would only con- 
sider as subdivisions of longer periods, what some 
palaeontologists are inclined to consider as distinct 
periods. 
8 The principal Monographs relating to special 
classes or families, are the following; Polyps and 
Infusoria: Michelin, (H.,) Iconographie Zoophy- 
tologique, Paris, 1841-45, 4to. fig. - Edwards, (IL 
Milne,) et Haime, (J.,) Recherches, etc., q. a., p. 31. 
- Polypiers fossiles des terrains paleozoiques, Arch. 
Mus., vol. 5. - Monograph of the British Fossil 
Corals, Palmont. Soc., London, 1850-55, 4to. fig. - 
Lonsdale, (W.,) On the Corals from the Tertiary 
Formations of North America, Journ. Geol. Soc., I., 
p. 495; Sill. Journ., 2d ser. IV., p. 357. - McCoy, 
(Fr.,) Contributions to British Paleontology, Cam- 
bridge, 1854, 1 vol. 8vo. fig. - References to all 
minor papers may be found in Edwards and Haime's 
Recherches. - Ehrenberg, (C. G.,) Mikrogeologie, 
Leipzig, 1854, fol. fig. - Echinoderms: Miller, (J. 
C.,) A Natural History of the Crinoidea, Bristol, 
1821, 4to. fig. - Orbigny, (Alc. d',) Histoire 
naturelle generale et particuliere des Crinoides vivans 
et fossiles, Paris, 1840, 4to. fig. - Austin, (Th. and 
Th. Jr.,) Monograph on Recent and Fossil Crinoidea, 
Bristol, 4to. fig. (without date.) - Hall, (J.,) Chap. I. 
SUCCESSION OF ANIMALS AND PLANTS. 
97 
tions into distinct faunae during each period, not to speak of the causes, or even 
the circumstances, under which these changes may have taken place. 
Pakeont. of New York, q. a.- Goldfuss, (G. A.,) 
Petref. Germ., q. a. - DeKoninck, (L.,) et LeIIon, 
(II.,) Recherches sur les Crinoides, etc., Bruxelles, 
1854, 4to. fig. - Owen, (D. D.,) and Shumard, (B. 
F.,) Description of New Species of Crinoidea, Journ. 
Ac. Nat. Sc., Philad. 1850, 4to. fig. - Sismonda, 
(E.,) Monographia degli Echinidi fossili del Pie- 
monte, Torino, 1840, 4to. fig.- DesMoulins, (C.,) 
Etude sur les Echinides, Bordeaux, 1835-37, 8vo. 
fig. - Agassiz, (L.,) Monogr. Echin., q. a., p. 54. - 
Catalogue raisonne, etc., q. a., p. 31. I quote this 
paper under my name alone, because that of Mr. 
Desor, which is added to it, has no right there. It 
was added by him, after I had left Europe, not only 
without authority, but even without my learning it, 
for a whole year. The genera Goniocidaris, Mespi- 
lia, Boletia, Lenita, Gualteria, Lovenia, Breynia, 
which bear his name, while they should bear mine, 
as I have established and named them, while Mr. 
Desor was travelling in Sweden, were appropriated 
by him, without any more right, by a mere dash of the 
pen, while he was carrying my manuscript through 
the press. How many species he has taken to him- 
self, in the same manner, I cannot tell. As the 
printed work, and a paper presented by me to the 
Academy of Sciences of Paris, in 1846, exhibit, for 
every one acquainted with zoological nomenclature, 
internal evidence of my statement, such, for instance, 
as my name left standing as authority for the species 
of Mespilia, Lenita, Gualteria, and Breynia, while 
the genus bears his, I need not allude further to the 
subject. This is one of the most extraordinary cases 
of plagiarism I know of. - Desor, (E.,) Synopsis des 
Echinides fossiles, Paris, 1854-56, 8vo. fig.; partly 
reprinted from my Catalogue, with additions and 
figures. - Buch, (L. v.,) Ueber die Cystideen, Ber- 
lin, 1844, 4to. fig.; Ak. d. wiss. - Muller, (J.,) 
Ueber den Bau der Echinodermen, Berlin, 1854, 4to. 
fig. - Roemer, (F.,) Ueber Stephanocrinus, etc., 
Wiegm. Arch., 1850, p. 365. - Monographie der 
fossilen Crinoidenfamilie der Blastoideen, etc., Wiegm. 
Arch., 1851, p. 323. - Forbes, (Ed.,) Echino- 
dermata of the British Tertiaries, (Palsnont. Soc.,) 
1852, 4to. fig. - Mem. of the Geol. Surv. of the 
Unit. Kingdom, London, 1849, 8vo. fig., Dec. 1st, 3d, 
and 4th. - Mollusks: DesHayes, (G. P.,) Traite 
elementaire de Conchyliologie, etc., Paris, 1835-39, 
2 vols. 8vo. fig. - Description des coquilles carac- 
teristique des terrains, Paris, 1831, 8vo. fig. - Wood- 
ward, (S. P.,) A Manual of the Mollusca, etc., 
London, 1851-54, 12mo. fig.- IIagenow, (Fr. v.,) 
Die Bryozoen der Maastrichter Kreideformation, 
Cassel, 1851, 4to. fig. - DesMoulins, (C.,) Essai 
sur les Spherulites, Bull. Soc. Lin., Bordeaux, 1827. 
- Roquan, (0. R. du,) Description des Coquilles 
fossilles de la famille des Rudistes, etc., Carcassonne, 
1841, 4to. fig. - Hoeninghaus, (Fr. W.,) Mono- 
graphic der Gattung Crania, Dusseldorf, 1828, 4to. 
fig. - Buch, (L. v.,) Ueber Terebrateln, etc., Berlin, 
1834, 4to. fig.; Ak. d. wiss.- Ueber Productus und 
Leptaena, Berlin, 1842, 4to. fig.; Ak. d. wiss. - 
Davidson, (Th.,) British Brachiopoda, (Pakeont. 
Soc.,) London, 1851-55, 4to. fig. - DeKoninck, (L.,) 
Recherches sur les animaux fossiles, Liege, 1847, 4to. 
fig.- Agassiz, (L.,) Etudes crit. q. a., p. 54.- Favre, 
(A.,) Observations sur les Dicerates, Geneve, 1843, 
4to. fig. - Bellardi, (L.,) e Michelotti, (G.,) 
Saggio orittografico sulla classe dei Gasteropodi fossili, 
Torino, 1840, 4to. fig. - DeHaan, (W.,) Mono- 
graphice Ammoniteorum et Goniatiteorum Specimen, 
Lugduni-Batav., 1825, 8vo. - Buch, (L. v.,) Ueber 
Ammoniten, fiber ihre Sonderung in Familien, etc., 
Berlin, 1832, 4to. fig. Ak. d. wiss. - Ueber Gonio- 
titen und Clymenien in Schlesien, Berlin, 1839, 4to. 
fig.; Ak. d. wiss. - Munster, (Gr. v.,) Ueber 
Goniatiten und Planuliten im Uebergangskalk, etc., 
Baireuth, 1832, 4to. fig. - Voltz, (Ph. L.,) Obser- 
vations sur les Belemnites, Paris, 1830, 4to. fig.- 
Quenstedt, (F. A.,) De Notis Nautileorum pri- 
mariis, etc., Berolini, 1834, 8vo. - Crustacea : Bron- 
gniart, (Al.,) et Desmarest, (A. G.,) Histoire 
naturelie des Trilobites, etc., Paris, 1822, 4to. fig.- 
Dalman, (J. W.,) Ueber die Palaeaden oder die 
sogenannten Trilobiten, a. d. Schwed., Nurnberg, 98 
ESSAY ON CLASSIFICATION. 
Part I. 
In order to be able to compare the order of succession of the animals of past 
ages with some other prominent traits of the animal kingdom, it is necessary for 
1828, 4to. fig. - Green, (J.,) A Monograph of the 
Trilobites of North America, etc., Philadelphia, 1833, 
8vo. fig. - Emmerich, (II. F.,) De Trilobitis, Bero- 
lini, 1839, 8vo. fig. - Zur Naturgeschichte der Trilo- 
biten, Meiningen, 1844, 4to. - Burmeister, (H.,) 
Die Organisation der Trilobiten, Berlin, 1843, 
4to. fig.; (Ray Society.) - Beyrich, (E.,) Ueber 
einige bbhmische Trilobiten, Berlin, 1845, 4to.; 2d 
part, 1846, 4to. - Corda, (A. J. C.,) und Hawle, 
(Ig.,) Prodrom einer Monographic der bohmischen 
Trilobiten, Prag, 1848, 8vo. fig. - Barrande, (J.,) 
Syst. Sih, q. a., p. 23. - Salter, (J. W.,) In Mem. 
Geol. Surv., etc., Dec. 2d. - Munster, (Gr. G. v.,) 
Beitrage zur Petrefaktenkunde, Beyreuth, 1839, 4to. 
2d Fasc., fig. - Meyer, (II. v.,) Neue Gattungen 
fossiler Krebse, etc., Stuttgart, 1840, 4to. fig. - De 
Koninck, (L.,) Memoire sur les Crustaces fossiles 
de Belgique, Liege, 1841, 4to. fig. - Cornuel, (J.,) 
Description des Entomostracds fossiles, etc., Mem. Soc. 
Geol. de France, 2de ser., vol. 1, part 2d, Paris, 
1846, 4to. fig.- Bosquet, Description des Ento- 
mostraces fossiles de la Craie de Maestricht, Mem. 
Soc. Roy. de Liege, 1847, 8vo. - Jones, (T. R.,) 
The Entomostraca of the Cretaceous Formation of 
England, (Paheont. Soc.,) London, 1848, 4to. fig.- 
Darwin, (Ch.,) Fossil Cirripedia, (Paheont. Soc.,) 
London, 1851 and 1854, 4to. fig. - Insects: Brodie, 
(P. B.,) History of the Fossil Insects of the Second- 
ary Rocks of England, London, 1845, 8vo.- Heer, 
(O.,) Die Insektenfauna der Tertiargebilde von 
Ocningen und von Radeboy, Leipzig, 1853, 4to. 
fig.; N. Denk., helv. Gessellsch. - Heer, (O.,) et 
Escher v. der Linth, (A.,) Zwei geologische Vor- 
triige, etc., Zurich, 1852, 4to. - Fishes: Agassiz, 
(L.,) Rech. s. les poiss. foss., q. a., p. 54. - Egerton, 
(Sir Phil.,) A Systematic and Stratigraphical Cata- 
logue of the Fossil Fishes, etc., London, 1837, 4to. 
2d edit. - On some new Ganoid Fishes, Proc. Geol. 
Soc. London, IV., p. 183. - On some New Species of 
Chimaeroid Fishes, Ibid., p. 153 and 211, and several 
other papers in Trans. Geol. Soc. Lond.; Journ. 
Geol. Soc.; Ann. and Mag. Nat. Hist., and Memoirs 
of the Geol. Surv. of the United Kingdom, Dec. 6th. 
- Pictet, (F. J.,) Poissons fossiles du Mt. Liban, 
Geneve, 1850, 4to. fig. - Heckel, (J. J.,) Beitrage 
zur Kenntniss der fossilen Fische Oesterreichs, Wien, 
1849, 4to. fig. - Gibbes, (R. W.,) Monograph of the 
Fossil Squalidae of the United States, Journ. Ac. Nat. 
Sc., Philadelphia, 1848 and 1849, 4to. fig. - New 
Species of Myliobates, Ibid., 1849, p. 299. - McCoy, 
(F.,) In Sedgwick and McCoy's British Palaeoz. 
Rocks, q. a., p. 23. - Newberry, (J. S.,) Fishes of 
the Carbonif. Deposits of Ohio, Proc. Ac. Nat. Sc., 
Philadelphia, 1856. - Reptiles-. Cuvier, (G.,) Rech. 
Oss. foss., q. a., p. 93. - Jaeger, (G. Fr.,) Ueber 
die fossilen Reptilien welche in Wiirtemberg aufge- 
funden worden sind, Stuttgart, 1828, 4to. fig. - 
Geoffroy St. Hilaire, (Et.,) Recherches sur les 
grands Sauriens, etc., Paris, 1831, 4to. fig. - Des- 
longchamps, (Eud.,) Mem. sur le Poecilopleuron 
Bucklandi, Caen, 1837, 4to. fig. - Bronn, (H. G.,) 
und Kaup, (J. J.,) Abhandlungen fiber die Gavial- 
artigen Reptilien, Stuttgart, 1842, fol. fig. - Gold- 
fuss, (A.,) Der Schiidelbau des Mosasaurus, N. Act. 
Ac. Nat. Car., 1844, 4to. fig. - Alton, (E. d',) und 
Burmeister, (H.,) Der fossile Gavial von Boll, 
Halle, 1854, fol. fig. - Burmeister, (H.,) Die 
Labyrinthodonten, Berlin, 1850, 4to. fig. - Quen- 
stedt, (A.,) Die Mastodonsaurier sind Batrachier, 
Tubingen, 1850, 4to. fig. - Gibbes, (R. W.,) A 
Memoir on Mosasaurus and three New Genera, etc., 
Smithson. Contrib. 1851, 4to. fig. - Meyer, (II. v.,) 
Zur Fauna der Vorwelt, Die Saurier des Muschel- 
kalkes, etc., Frankfurt a. M., 1845-52, fol. - Meyer, 
(II. v.,) und Plieninger, (Th.,) Beitrage zur Palae- 
ontologie Wiirtembergs, Stuttgart, 1844, 4to. fig.- 
Owen, (R.,) Report on British Fossil Reptiles, Brit. 
Ass. 1839, p. 43; 1841, p. 60. - Fossil Reptilia of 
the London Clay, (Palaeont. Soc.,) London, 1849, 4to. 
fig. (the Chelonia with T. Bell.) - Fossil Reptilia 
of the Cretaceous Formation, (Palmont. Soc.,) Lon- 
don, 1851, 4to. fig. - Fossil Reptilia of the Wealden 
Formation, (Palieont. Soc.,) London, 1852-55, 4to. 
fig. - Lea, (I.,) On a Fossil Saurian of the New Chap. I. 
SUCCESSION OF ANIMALS AND PLANTS. 
99 
me to make a few more remarks upon this topic. I can, fortunately, be very 
brief, as we possess a text-book of Palaeontology, arranged in zoological order, in 
which every one may at a glance see how, throughout all the classes of the animal 
kingdom, the different representatives of each, in past ages, are distributed in the 
successive geological formations.1 From such a cursory survey, it must appear, that 
while certain types prevail during some periods, they are entirely foreign to others. 
This limitation is conspicuous, with reference to entire classes among Vertebrata, 
while, in other types, it relates more to the orders, or to the families, and extends 
frequently only to the genera or the species. But, whatever be the extent of 
their range in time, we shall see presently, that all these types bear, as far as 
the order of their succession is concerned, the closest relation to the relative rank 
of living animals of the same types compared with one another, to the phases of 
the embryonic growth of these types in the present day, and even to their geo- 
graphical distribution upon the present surface of our globe. I will, however, select 
Red Sandstone, etc., Philadelphia, 1852, 4to. tig. - 
Leidy, (Jos.,) Description of Extinct Mammalia and 
Chelonia from Nebraska Territory, in D. D. Owen, 
Geol. Surv. of Wisconsin, Iowa, Minesota, etc., 
Philadelphia, 1852, 4to. fig. - On Bathygnathus 
borealis, an extinct Saurian, Journ. Ac. Nat. Sc., 
Philad., 1854, 4to. fig. - Description of a New Species 
of Crocodile, etc., Ibid., 1851. - Birds: Owen, (R.,) 
History of British Fossil Mammalia and Birds, Lon- 
don, 1844-46, 1 vol. 8vo. fig. - Fossil Birds from the 
Wealden, Journ. Geol. Soc., IL, p. 96. - Memoir on 
the Dinornis, Trans. Zool. Soc., vol. 3, p. 3, London, 
1844, 4to. fig. - Mammalia : Cuvier, (G.,) Oss. foss., 
q. a. - Buckland, (W.,) Rei. Diluv., q. a., p. 94. -• 
DeBlainville, (Ducr.,) Osteographie ou Descrip- 
tion iconographique comparee du Squelette, etc., 
Paris, 1841, et suiv. 4to., Atlas fol. - Kaup, (J. J.,) 
Descriptions d'ossemens fossiles de Mammiferes incon- 
nus, Darmstadt, 1832-39, 4to. fig. - Owen, (R.,) 
Odontography, or a Treatise on the Comparative 
Anatomy of the Teeth, London, 1840-41, 3 vols. 8vo. 
fig. - Brit. foss. Mam. and Birds, q. a.-The Fossil 
Mammalia of the Voyage of II. M. S. Beagle, 
London, 1838, 4to. fig.- Description of the Skeleton 
of an extinct gigantic Sloth, Mylodon robustus, Lon- 
don, 1842, 4to. fig.; and many papers in Journal 
of Geological Society; Trans. Zool. Society, etc. - 
Sciimerling, (P. C.,) Recherches sur les ossemens 
fossiles des cavernes de Liege, Liege, 1833-36, 
2 vols. 4to. fig.- Croizet et Jobert, Recherches 
sur les ossemens fossiles du departement du Puy-de- 
Dome, Paris, 1828, fol. fig. - Meyer, (H. v.,) Zur 
Fauna, etc., q. a. - Die fossilen Ziihne und Knochen, 
in der Gegend von Georgensgmund, Frankfurt a. M., 
1834, 4to. fig.-Jaeger, (G. Fr.,) Die fossilen 
Saugethiere Wiirtembergs, Stuttgardt, 1835-39, fol. 
fig. - Falconer, (H.,) and Cautley, (P. T.,) 
Fauna antiqua sivalensis, etc., London, 1846, fol. fig. 
- Gervais, (P.,) Zoologie et Paleontologie fran- 
§aises, Paris, 1848-52, 4to. fig. - Muller, (J.,) 
Ueber die fossilen Reste der Zeuglodonten, etc., 
Berlin, 1849, fol. fig. - LeConte, (J.,) On Platy- 
gonus compressus, Mem. Amer. Acad. Arts and Sc., 
1848, 4to. fig. - Wyman, (J.,) Notice of the Geo- 
logical Position of Castoroides ohioensis, by J. Hall, 
and an Anatomical Description of the same, Boston 
Journ. Nat. Hist., 1847, vol. 5, p. 385, 8vo. fig. - 
Warren, (J. C.,) Description of a Skeleton of the 
Mastodon giganteus, Boston, 1852, 4to. fol. - Leidy, 
(J.,) The Ancient Fauna of Nebraska, Smith. Contr., 
Washington, 1852, 4to. fig. See also Sect. 22. 
1 I allude to the classical work of Pictet, Traite 
elementaire de Paleontologie, q. a., a second edition 
of which is now publishing. 100 
ESSAY ON CLASSIFICATION. 
Part I. 
it few examples for further discussion. Among Echinoderms the Crinoids are, for 
a long succession of periods, the only representatives of that class; next follow 
the Starfishes, and next the Sea-Urchins, the oldest of which belong to the type 
of Cidaris and Echinus, followed by Clypeastroids and Spatangoids. No satisfactory 
evidence of the existence of Holothuriae has yet been found. Among Crustacea, 
a comparison of the splendid work of Barrande1 upon the Silurian System of 
Bohemia, with the paper of Count Munster upon the Crustacea of Solenhofen,2 and 
with the work of Desmarest upon fossil Crabs,3 will at once show that while 
Trilobites are the only Crustacea of the oldest palaeozoic rocks, there is found in 
the Jurassic period a carcinological fauna entirely composed of Macrura, to which 
Brachyura are added in the tertiary period. The formations intermediate between 
the older palaeozoic rocks and the Jura contain the remains of other Entomostraca, 
and later of some Macroura also. In both classes the succession of their repre- 
sentatives, in different periods, agrees with their respective standing, as determined 
by the gradation of their structure. 
Among plants, we find in the Carboniferous period prominently, Ferns and 
Lycopodiaceae;4 in the Triassic period Equisetaceae6 and Coniferae prevail; in the 
Jurassic deposits, Cycadeae,6 and Monocotyledoneae; while later only Dicotyledoneae 
take the lead.7 The monographic illustration of the vegetation of past ages has 
of late advanced beyond the attempts to represent the characteristic features of 
the animal world in different geological periods.8 
Without attempting here to characterize this order of succession, this much follows 
already from the facts mentioned, that while the material world is ever the same 
through all ages in all its combinations, as far back as direct investigations can 
trace its existence, organized beings, on the contrary, transform these same mate- 
rials into ever new forms and new combinations. The carbonate of lime of all 
ages is the same carbonate of lime in form as well as composition, as long as it 
is under the action of physical agents only. Let life be introduced upon earth, 
1 Barrande's Syst Silur., q, a., p. 23. 
2 Gr. G. v. Munster, Beitrage zur Petrefacten- 
kunde, q. a., p. 98. 
3 Desmarest, see Brongniart and Desmarest's 
Hist. Nat. d. Tril. et Crust, q. a., p. 97. 
4 See, above, p. 93. 
5 Schimper, (W. P.,) et Mougeot, (A.,) Mono- 
graphic des Plantes Fossiles du Gres-bigarre de la 
chaine des Vosges, Strasb. et Paris, 1840-43, 4to. 
fig. 
6 Buckland, (W.,) On the Cycadeoidae, a Family 
of Plants found in the Oolite, etc., Trans. Geol. Soc. 
Lond. 2d ser. II., p. 395. 
7 Unger, (Fr.,) Chloris protogaea, Beitrage zur 
Flora der Vorwelt, Leipzig, 1841, 4to. fig. - Heer, 
(O.,) Flora tertiaria Helvetia?, Wintherthur, 1855, 
fol. fig. 
8 Landscapes of the different geological periods 
are represented in Unger, (Fr.,) Die Vorwelt in 
ihren vershiedenen Bildungsperioden, Wien, fol. (no 
date.) These landscapes are ideal representations of 
the vegetation of past ages. Chap. I. 
SUCCESSION OF ANIMALS AND PLANTS. 
101 
and a Polyp builds its coral out of it, and each family, each genus, each species 
a different one, and different ones for all successive geological epochs. Phosphate 
of lime in palaeozoic rocks is the same phosphate, as when prepared artificially by 
Man; but a Fish makes its spines out of it, and every Fish in its own way, a 
Turtle its shield, a Bird its wings, a Quadruped its legs, and Man, like all other 
Vertebrates, its whole skeleton, and during each successive period in the history 
of our globe, these structures are different for different species. What similarity is 
there between these facts! Do they not plainly indicate the working of different 
agencies excluding one another? Truly the noble frame of Man does not owe its 
origin to the same forces which combine to give a definite shape to the crystal. 
And what is true of the carbonate of lime, is equally true of all inorganic sub- 
stances ; they present the same characters in all ages past, as those they exhibit now. 
Let us look upon the subject in still another light, and we shall see that the 
same is also true of the influence of all physical causes. Among these agents, the 
most powerful is certainly electricity; the only one to which, though erroneously, the 
formation of animals has ever been directly ascribed. The effects it may now 
produce, it has always produced, and produced them in the same manner. It has 
reduced metallic ores and various earthy minerals and deposited them in crystalline 
form, in veins, during all geological ages; it has transported these and other 
substances from one point to another, in times past, as we may do now in our 
laboratories, under its influence. Evaporation upon the surface of the earth has 
always produced clouds in the atmosphere, which after accumulating have been 
condensed in rain showers in past ages as now. Rain drop marks in the carbonifer- 
ous and triassic rocks have brought to us this testimony of the identity of the 
operation of physical agents in past ages, to remind us that what these agents may 
do now, they already did in the same way, in the oldest geological times, and have 
done at all times. Who could, in presence of such facts, assume any causal con- 
nection between two series of phenomena, the one of which is ever obeying the 
same laws, while the other presents at every successive period new relations, an 
ever changing gradation of new combinations, leading to a final climax with the 
appearance of Man? Who does not see, on the contrary, that this identity of the 
products of physical agents in all ages, totally disproves any influence on their part 
in the production of these ever changing beings, which constitute the organic world, 
and which exhibit, as a whole, such striking evidence of connected thoughts! 102 
ESSAY ON CLASSIFICATION. 
Part I. 
SECTION XXII. 
LOCALIZATION OF TYPES IN PAST AGES. 
The study of the geographical distribution of the animals now living upon 
earth has taught us, that every species of animals and plants has a fixed home, and 
even that peculiar types may be circumscribed within definite limits, upon the 
surface of our globe. But it is only recently, since geological investigations have 
been carried on in remote parts of the world, that it has been ascertained that 
this special localization of types extends to past ages. Lund for the first time 
showed that the extinct Fauna of the Brazils,1 during the latest period of a past 
age, consists of different representatives of the very same types now prevalent in 
that continent; Owen has observed similar relations between the extinct Fauna 
of Australia2 and the types now living upon that continent. 
If there is any naturalist left who believes that the Fauna of one continent 
may be derived from another portion of the globe, the study of these facts, in 
all their bearing, may undeceive him. 
It is well known how characteristic the Edentata are for the present Fauna 
of the Brazils, for there is the home of the Sloths, (Bradypus,) the Tatous, 
(Dasypus,) the Ant-eaters, (Myrmecophaga); there also have been found those 
extraordinary extinct genera, the Megatherium, the Mylodon, the Megalonyx, the 
Glyptodon, and the many other genera described by Dr. Lund and Professor 
Owen, all of which belong to this same order of Edentata. Some of these 
extinct genera of Edentata had also representatives in North America, during the 
same geological period,3 thus showing that though limited within similar areas, the 
range of this type has been different in different epochs. 
Australia, at present almost exclusively the home of Marsupials, has yielded 
also a considerable number of equally remarkable species, and two extinct genera 
of that type, all described by Owen in a report to the British Association, in 
1844, and in Michell's Expeditions into the Interior of Australia. 
1 Lund, (Dr.,) Blik paa Brasiliens Dyreverden 
for sidste Jordomvaeltning. K. Danske Vidensk. 
Selsk. Afhandl. VIII., Kibbenhavn, 1841, 4to. fig., p. 
61, etc.; Engl. Abstract, Ann. and Mag. vol. 3, p. 
422. 
2 Owen, (R.,) On the Geographical Distribution 
of Extinct Mammalia, Ann. and Mag. Nat. Hist., 1846, 
vol. 17, p. 197. 
8 Leidy, (Jos.,) A Memoir on the Extinct Sloth 
Tribe of North America, Smithson. Contrib. 1855, 4to. 
fig. - Wyman, (J.,) Notice of Fossil Bones, etc., Am. 
Journ. Sc. and A., 2d ser., 1850, vol. 10. Chap. I. 
EARLY LOCALIZATION OF TYPES. 
103 
How far similar facts are likely to occur in other classes, remains to be ascer- 
tained. Our knowledge of the geographical distribution of the fossil remains is 
yet too fragmentary to furnish any further data upon this point. It is, however, 
worthy of remark, that though the types of the oldest geological periods had a 
much wider distribution than most recent families exhibit now, some families of 
fishes largely represented in the Devonian system of the Old World have not 
yet been noticed among the fossils of that period in America, as, for instance, 
the Cephalaspids, the Dipteri, and the Acanthodi. Again, of the many gigantic 
Reptiles of the Triasic and Oolitic periods, none are known to occur elsewhere 
except in Europe, and it can hardly be simply owing to the less extensive dis- 
tribution of these formations in other parts of the world, since other fossils of 
the same formations are known from other continents. It is more likely that 
some of them, at least, are peculiar to limited areas of the surface of the globe, 
as, even in Europe, their distribution is not extensive. 
Without, however, entering upon debatable ground, it remains evident, that 
before the establishment of the present state of things, peculiar types of animals, 
which were formerly circumscribed within definite limits, have continued to occupy 
the same or similar grounds in the present period, even though no genetic con- 
nection can be assumed between them, their representatives in these different forma- 
tions not even belonging to the same genera. Such facts are in the most direct 
contradiction with any assumption that physical agents could have any tiling to 
do with their origin; for though their occurrence within similar geographical areas 
might at first seem to favor such a view, it must be borne in mind that these 
so localized beings are associated with other types which have a much wider range, 
and, what is still more significant, they belong to different geological periods, 
between which great physical changes have undoubtedly taken place. Thus the 
facts indicate precisely the reverse of what the theory assumes; they prove a 
continued similarity of organized beings during successive geological periods, not- 
withstanding the extensive changes, in the prevailing physical conditions, which the 
country they inhabited may have undergone, at different periods. In whatever direc- 
tion this theory of the origin of animals and plants, under the influence of physical 
agents, is approached, it can nowhere stand a critical examination. Only the delib- 
erate intervention of an Intellect, acting consecutively, according to one plan, can 
account for phenomena of this kind. 104 
ESSAY ON CLASSIFICATION. 
Part I. 
SECTION XXIII. 
LIMITATION OF SPECIES TO PARTICULAR GEOLOGICAL PERIODS. 
Without entering into a discussion respecting the precise limits within which this 
fact is true, there can no longer be any doubt, that not only species, but all other 
groups of animals and plants, have a definite range of duration, as well as individ- 
uals.1 The limits of this duration, as far as species are concerned, generally coin- 
cide with great changes in the physical conditions of the earth's surface;2 though, 
strange to say, most of those investigators who would ascribe the origin of organ- 
ized beings to the influence of such causes, maintain also, that species may extend 
from one period to another, which implies that these are not affected by such 
changes.3 
When considering, in general, the limitation of species to particular geological 
periods, we might very properly disregard the question of the simultaneity of the 
successive appearance and disappearance of Faunae, as in no way affecting the 
result of the investigation, as long as it is universally conceded, that there is no 
species, known among the fossils, which extends through an indefinite series of 
geological formations. Moreover, the number of the species, still considered as 
identical in several successive periods, is growing smaller and smaller, in proportion 
as they are more closely compared. I have already shown, long ago, how widely 
many of the tertiary species, long considered as identical with living ones, differ 
from them,4 and also how different the species of the same family may be, in 
successive subdivisions of the same great geological formation.6 Hall has come to 
the same result in his investigations of the fossils of the State of New York.6 
Every monograph reduces their number, in every formation. Thus Barrande, who 
has devoted so many years to the most minute investigation of the Trilobites of 
1 Compare Sect. XIX. 
2 Elie de Beaumont, Recherches sur quelques- 
unes des Revolutions de la surface du Globe, Paris, 
1830, 1 vol. 8vo. 
8 For indications respecting the occurrence of all 
species of fossil organized beings now known, consult, 
Bronn, (H. G.,) Index palaeontologicus, Stuttgardt, 
1848-49, 3 vols. 8vo. - Orbigny, (A. d',) Prodrome 
de Paleontologie stratigraphique universelie etc., 
Paris, 1850, 2 vols. 12mo. - Morris, (J.,) Catalogue 
of the British Fossils, London, 1854, 1 vol. 8vo. 
4 Agassiz, (L.,) Coquilles tertiaires reputees 
identiques avec les especes vivantes, Neuchatel, 1845, 
4to. fig. 
5 Agassiz, (L.,) Etudes critiques sur les Mollus- 
ques fossiles, Neuchatel, 1840-45, 4to. fig. 
6 Hall, (J.,) Palaeontology of the State of New 
York, q. a., p. 23, note 1. Chap. I. 
LIMITATION OF SPECIES IN TIME. 
105 
Bohemia,1 has come to the conclusion that their species do not extend from one 
formation to the other; D'Orbigny2 and Pictet3 have come to the same conclusion 
for the fossil remains of all classes. It may well be said that, as fossil remains 
are studied more carefully, in a zoological point of view, the supposed identity of 
species, in different geological formations, vanishes gradually more and more; so 
that the limitation of species in time, already ascertained in a general way, by the 
earlier investigations of their remains in successive geological formations, is circum- 
scribed, step by step, within narrower, more definite, and also more equable periods. 
Species are truly limited in time, as they are limited in space, upon the surface of 
the globe. The facts do not exhibit a gradual disappearance of a limited number of 
species, and an equally gradual introduction of an equally limited number of new 
ones; but, on the contrary, the simultaneous creation and the simultaneous destruc- 
tion of entire faunae, and a coincidence between these changes in the organic world 
and the great physical changes our earth has undergone. Yet it would be premature 
to attempt to determine the extent of the geographical range of these changes, and 
still more questionable to assert their synchronism upon the whole surface of the 
globe, in the ocean and upon dry land. 
To form adequate ideas of the great physical changes the surface of our globe 
has undergone, and the frequency of these modifications of the character of the 
earth's surface, and of their coincidence with the changes observed among the organ- 
ized beings, it is necessary to study attentively the works of Elie de Beaumont.4 
He, for the first time, attempted to determine the relative age of the different sys- 
tems of mountains, and showed first, also, that the physical disturbances occasioned 
by their upheaval coincided with the successive disappearance of entire faunae, and 
the reappearance of new ones. In his earlier papers he recognized seven, then 
twelve, afterwards fifteen such great convulsions of the globe, and now he has 
traced more or less fully and conclusively the evidence that the number of these 
disturbances has been at least sixty, perhaps one hundred. But while the genesis 
and genealogy of our mountain systems were thus illustrated, palaeontologists, extend- 
ing their comparisons between the fossils of different formations more carefully to 
all the successive beds of each great era, have observed more and more marked 
differences between them, and satisfied themselves that faunae also have been more 
frequently renovated, than was formerly supposed; so that the general results of 
1 Barrande, Systeme silurien, etc., q. a.; see, 
also, my Monographies d'Echinodermes, q. a., p. 54. 
2 D'Orbigny, Paleontologie Fran^aise, q. a., p. 95. 
8 Pictet, Traite de Paleontologie, etc., q. a., p. 
96, note 1. 
4 Elie de Beaumont, Notice sur les systemes de 
Montagnes, Paris, 1852, 3 vols. 12mo.; see, also, 
Buch, (Leop. v.,) Ueber die geognotischen Systeme 
von Deutschland, Leonhard's Taschenb., 1824, II., p. 
501. 106 
ESSAY ON CLASSIFICATION. 
Part I. 
geology proper and of palaeontology concur in the main to prove, that while the 
globe has been at repeated intervals, and indeed frequently, though after immensely 
long periods, altered and altered again, until it has assumed its present condition, 
so have also animals and plants, living upon its surface, been again and again extin- 
guished and replaced by others, until those now living were called into existence 
with man at their head. The investigation is not in every case sufficiently com- 
plete to show everywhere a coincidence between this renovation of animals and 
plants and the great physical revolutions which have altered the general aspect of 
the globe, but it is already extensive enough to exhibit a frequent synchronism and 
correlation, and to warrant the expectation that it will, in the end, lead to a com- 
plete demonstration of their mutual dependence, not as cause and effect, but as steps 
in the same progressive development of a plan which embraces the physical as well 
as the organic world. 
In order not to misapprehend the facts, and perhaps to fall back upon the 
idea, that these changes may be the cause of the differences observed between the 
fossils of different periods, it must be well understood that, while organized beings 
exhibit through all geological formations a regular order of succession, the character 
of which will be more fully illustrated hereafter, this succession has been from 
time to time violently interrupted by physical disturbances, without any of these 
altering in any way the progressive character of that succession of organized beings. 
Truly this shows that the important, the leading feature of this whole drama is 
the development of life,1 and that the material world affords only the elements for 
its realization. The simultaneous disappearance of entire fauna), and the following 
simultaneous appearance of other fauna), show further that, as all these faunae con- 
sist of the greatest variety of types,2 in all formations, combined everywhere into 
natural associations of animals and plants, between which there have been definite 
relations at all times, their origin can at no time be owing to the limited influence 
of monotonous physical causes, ever acting in the same way. Here, again, the 
intervention of a Creator is displayed in the most striking manner, in every stage 
of the history of the world. 
1 Dana, (J. D.,) Address, q. a., p. 94, note 1. 
2 Agassiz, (L.,) Geol. Times, q. a., p. 25 Chap. I. 
SUCCESSION AND STANDING OF ANIMALS. 
107 
SECTION XXIV. 
PARALLELISM BETWEEN THE GEOLOGICAL SUCCESSION OF ANIMALS AND PLANTS AND 
THEIR PRESENT RELATIVE STANDING. 
The total absence of the highest representatives of the animal kingdom in the 
oldest deposits forming part of the crust of our globe, has naturally led to the 
very general belief, that the animals which have existed during the earliest period 
of the history of our earth were inferior to those now living, nay, that there is 
a natural gradation from the oldest and lowest animals to the highest now in exist- 
ence.1 To some extent this is true; but it is certainly not true that all animals 
form one simple series from the earliest times, during which only the lowest types 
of animals would have been represented, to the last period, when Man appeared 
at the head of the animal creation.2 It has already been shown (Sect. VII.) that 
representatives of all the great types of the animal kingdom have existed from the 
beginning of the creation of organized beings. It is therefore not in the succes- 
sive appearance of the great branches of the animal kingdom, that we may expect 
to trace a parallelism between their succession in geological times and their relative 
standing at present. Nor can any such correspondence be observed between the 
appearance of classes, at least not among Radiata, Mollusks, and Articulata, as their 
respective classes seem to have been introduced simultaneously upon our earth, with 
perhaps the sole exception of the Insects, which are not known to have existed 
before the Carboniferous period. Among Vertebrata, however, there appears already a 
certain coincidence, even within the limits of the classes, between the time of their 
introduction, and the rank their representatives hold, in comparison to one another. 
But upon this point more hereafter. 
It is only within the limits of the different orders of each class, that the paral- 
lelism between the succession of their representatives in past ages and their respec- 
tive rank, in the present period, is decidedly characteristic. But if this is true, it 
must be at the same time obvious to what extent the recognition of this corre- 
spondence may be influenced by the state of our knowledge of the true affinities 
and natural gradation of living animals, and that until our classifications have become 
the correct expression of these natural relations, even the most striking coincidence 
with the succession of their representatives in past ages may be entirely overlooked. 
On that account it would be presumptuous on my part to pretend, that I could 
1 See the palaeontological works quoted in Sect. 21. 
2 Agassiz, (L.,) Twelve Leet., etc., p. 25 and 69. 108 
ESSAY ON CLASSIFICATION. 
Part I. 
illustrate this proposition, through the whole animal kingdom, as such an attempt 
would involve the assertion that I know all these relations, or that where there 
exists a discrepancy between the classification and the succession of animals, the 
classification must be incorrect, or the relationship of the fossils incorrectly appre- 
ciated. I shall therefore limit myself here to a general comparison, which may, 
however, be sufficient to show, that the improvements which have been introduced 
in our systems, upon purely zoological grounds, have nevertheless tended to render 
more apparent the coincidence between the relative standing among living animals 
and the order of succession of their representatives in past ages. I have lately 
attempted to show, that the order of Halcyonoids, among Polyps, is superior to that 
of Actinoids;1 that, in this class, compound communities constitute a higher degree of 
development, when contrasted with the characters and mode of existence of single 
Polyps, as exhibited by the Actinia; that top-budding is superior to lateral budding; 
and that the type of Madrepores, with their top-animal, or at least with a defi- 
nite and limited number of tentacles, is superior to all other Actinoids. If this be 
so, the prevalence of Actinoids in older geological formations, to the exclusion of 
Halcyonoids, the prevalence of Rugosa and Tabulata in the oldest deposits,2 the 
later prevalence of Astrseoids, and the very late introduction of Madrepores, would 
already exhibit a correspondence between the rank of the living Polyps and the 
representatives of that class in past ages, though we may hardly expect a very close 
coincidence in this respect between animals the structure of which is so simple. 
The gradation among the orders of Echinoderms is perfectly plain. Lowest 
stand the Crinoids, next the Asterioids, next the Echinoids, and highest the Holo- 
thurioids. Ever since this class has been circumscribed within its natural limits, 
this succession has been considered as expressing their natural relative standing, and 
modern investigations respecting their anatomy and embryology, however extensive, 
have not led to any important change in their classification, as far as the estimation 
of their rank is concerned. This is also precisely the order in which the representa- 
tives of this class have successively been introduced upon earth in past geological ages. 
Among the oldest formations we find pedunculated Cinoids3 only, and this order 
remains prominent for a long series of successive periods; next come free Crinoids 
and Asterioids; next Echinoids,4 the successive appearance of which since the triasic 
1 For classification of Polypi, see Dana, q. a., p. 
31, note 2; also Milne-Edwards and Haime, q. a., 
and Agassiz, (L.,) Classification of Polyps, Proc. 
Am. Acad. Sc. and Arts, 1856, p. 187. 
2 See Milne-Edwards and Haime, q. a., p. 31. 
8 Miller, Crinoids, q. a. - D'Orbigny, q. a. - 
J. Hall, q. a. - Austin, q. a., p. 96. 
4 See the works q. a., p. 96 ; also : Muller, (J.,) 
and Troschel, (F. IL,) System der Asteriden, 
Braunschweig, 1842, 4to. fig. - Muller, (J.,) Ueber 
den Bau der Echinodermen, Berlin, 1854, 4to. - Tie- 
deman, (Fr.,) Anatomie der Rohren-Holothurie, des 
Seeigels, etc., Landshut, 1817, fol. fig. - Valentin, 
(G.,) Anat, du gerne Echinus, Neuchatel, 1842, 4to. Chap. I. 
SUCCESSION AND STANDING OF ANIMALS. 
109 
period to the present day, coincides also with the gradation of their subdivisions, 
as determined by their structure; and it was not until the present period, that the 
highest Echinoderms, the Holothurioids, have assumed a prominent position in their 
class. 
Among Acephala there is not any more uncertainty respecting the relative rank 
of their living representatives, than among Echinoderms. Every zoologist acknowl- 
edges the inferiority of the Bryozoa and the Brachiopods1 when compared with the 
Lamellibranchiata, and among these the inferiority of the Monomyaria in compari- 
son with the Dimyaria would hardly be denied. Now if any fact is well established 
in Palaeontology, it is the earlier appearance and prevalence of Bryozoa and Bra- 
chiopods in the oldest geological formations, and their extraordinary development 
for a long succession of ages, until Lamellibranchiata assume the ascendency which 
they maintain to the fullest extent at present. A closer comparison of the differ- 
ent families of these orders might further show how close this correspondence is 
through all ages. 
Of Gasteropoda I have nothing special to say, as every palaeontologist is aware 
how imperfectly their remains have been investigated in comparison with what has 
been done for the fossils of other classes. Yet the Pulmonata are known to be 
of more recent origin than the Branchifera, and among these the Siphonostomata 
to have appeared later than the Holostomata, and this exhibits already a general 
coincidence between their succession in time and their respective rank. 
Our present knowledge of the anatomy of the Nautilus, for which science is 
indebted to the skill of Owen,2 may satisfy everybody that among Cephalopods the 
Tetrabranchiata are inferior to the Dibranchiata; and it is not too much to say, 
that one of the first points a collector of fossils may ascertain for himself, is the 
exclusive prevalence of the representatives of the first of these types in the oldest 
formations, and the later appearance, about the middle geological ages, of represent- 
atives of the other type, which at present is the most widely distributed. 
Of Worms, nothing can be said of importance with reference to our inquiry; 
1 Orbigny, (A. d',) Bryozoires, Ann. Sc. Nat., 3e 
ser. 1851, vol. 16, p. 292.- Cuvier, (G.,) Memoire 
sur l'animal de la Lingule, Ann. Mus. I., p. 69, fig. - 
Vogt, (C.,) Anatomie der Lingula anatina, N. Mem. 
Soc. Helv. 1843, VIL, 4to. fig. -Owen, (R.,) On the 
Anatomy of the Brachiopoda, Trans. Zool. Soc., I. 
4to., p. 145, fig.- On the Anatomy of the Terebratula, 
1853, 4to. fig. (Palaeont. Soc.)-Buch, (L. v.,) Ueber 
Terebrateln, q. a., p. 97.-Davidson, (Th.,) Monogr. 
etc., q. a., p. 97. - Poli (Xav.,) Testacea utriusque 
Sicilias, eorumque Historia et Anatomia, Parmae, 
1791-93, 2 vols. fol. fig., continued by Delle Chiaje. 
2 Owen, (R.,) Memoir on the Pearly Nautilus, 
London, 1832, 4to. fig. - Valenciennes, (A.,) Nou- 
yelles Becherches anatomiques sur le Nautile. C. R., 
Paris, 1841, 4to. - Cuvier, (G.,) Memoires pour 
servir a 1'IIistoire et a l'Anatomie des Mollusques, 
Paris, 1817, 4to. fig. - Edwards, (H. M.,) Quatre- 
fages, (Ar. de,) et Blanchard, (Em.) Voyage en 
Sicile, Paris, 3 vols. 4to. fig. (without date.) 110 
ESSAY ON CLASSIFICATION. 
Part I. 
but the Crustacea exhibit, again, the most striking coincidence. Without entering 
into details, it appears from the classification of Milne-Edwards that Decapods, Sto- 
mapods, Amphipods, and Isopods constitute the higher orders, while Branchiopods, 
Entomostraca, Trilobites, and the parasitic types, constitute, with Limulus, the lower 
orders of this class.1 In the classification of Dana,2 his first type embraces Deca- 
pods and Stomapods, the second Amphipods and Isopods, the third Entomostraca, 
including Branchiopods, the fourth Cirripedia, and the fifth Rotatoria. Both acknowl- 
edge in the main the same gradation; though they differ greatly in the combina- 
tion of the leading groups, and also the exclusion by Milne-Edwards of some types, 
as the Rotifera, which Burmeister first, then Dana and Leydig, unite justly, as I 
believe, with the Crustacea.3 This gradation now presents the most perfect coinci- 
dence with the order of succession of Crustacea in past geological ages, even down 
to their subdivisions into minor groups. Trilobites and Entomostraca are the only 
representatives of the class in palaeozoic rocks; in the middle geological ages appear 
a variety of Shrimb, among which the Macrouran Decapods are prominent, and later 
only the Brachyoura, which are the most numerous in our days. 
The fragmentary knowledge we possess of the fossil Insects, does not justify 
us, yet, in expecting to ascertain with any degree of precision, the character of 
their succession through all geological formations, though much valuable information 
has already been obtained respecting the entomological faunae of several geological 
periods.4 
The order of succession of Vertebrata in past ages, exhibits features in many 
respects differing greatly from the Articulata, Mollusks, and Radiata. Among these 
we find their respective classes appearing simultaneously in the oldest periods of 
the history of our earth. Not so with the Vertebrata, for though Fishes may be 
as old as any of the lower classes, Reptiles, Birds, and Mammalia are introduced 
successively in the order of their relative rank in their type. Again, the earliest 
representatives of these classes do not always seem to be the lowest; on the con- 
trary, they are to a certain extent, and in a certain sense, the highest, in as far 
as they embody characters, which, in later periods, appear separately in higher 
classes, (See Sect. 26,) to the exclusion of what henceforth constitutes the special 
character of the lower class. For instance, the oldest Fishes known partake of 
the characters, which, at a later time, are exclusively found in Reptiles, and no 
longer belong to the Fishes of the present day. It may be said, that the earliest 
Fishes are rather the oldest representatives of the type of Vertebrata than of the 
1 Milne-Edwards, Hist. Nat. des Crustaces, 
Paris, 1834-40, 3 vols. 8vo. 
2 Dana, (J. D.,) Crustacea, q. a., p. 32. 
3 Leydig, (Fr.,) Riiderthiere, etc., Zeitsch. f. 
wiss. Zool. 1854, vol. 6, p. 1. 
4 Heer, q. a.; Brodie, q. a., p. 98. Chap. I. 
SUCCESSION AND STANDING OF ANIMALS. 
111 
class of Fishes, and that this class assumes only its proper characters after the 
introduction of the class of Reptiles upon earth. Similar relations may be traced 
between the Reptiles and the classes of Birds and Mammalia, which they precede. 
I need only allude here to the resemblance of the Pterodactyl! and the Birds, and 
to that of Ichthyosauri and certain Cetacea. Yet, through all these intricate rela- 
tions, there runs an evident tendency towards the production of higher and higher 
types, until at last, Man crowns the whole series. Seen as it were at a distance, 
so that the mind can take a general survey of the whole, and perceive the con- 
nection of the successive steps, without being bewildered by the details, such a 
series appears like the development of a great conception, expressed in such har- 
monious proportions, that every link appears necessary to the full comprehension 
of its meaning, and yet, so independent and perfect in itself, that it might be 
mistaken for a complete whole, and again, so intimately connected with the pre- 
ceding and following members of the series, that one might be viewed as flowing 
out of the other. What is universally acknowledged as characteristic of the highest 
conceptions of genius, is here displayed in a fulness, a richness, a magnificence, 
an amplitude, a perfection of details, a complication of relations, which baffle our 
skill and our most persevering efforts to appreciate all its beauties. Who can 
look upon such series, coinciding to such an extent, and not read in them the 
successive manifestations of a thought, expressed at different times, in ever new 
forms, and yet tending to the same end, onwards to the coming of Man, whose 
advent is already prophesied in the first appearance of the earliest Fishes! 
The relative standing of plants presents a somewhat different character from that 
of animals. Their great types are not built upon so strictly different plans of 
structure; they exhibit, therefore, a more uniform gradation from their lowest to 
their highest types, which are not personified in one highest plant, as the highest 
animals are in Man. 
Again, Zoology is more advanced respecting the limitation of the most compre- 
hensive general divisions, than Botany, while Botany is in advance respecting the 
limitation and characteristics of families and genera. There is, on that account, more 
diversity of opinion among botanists respecting the number, and the relative rank 
of the primary divisions of the vegetable kingdom, than among zoologists respecting 
the great branches of the animal kingdom. While most writers1 agree in admitting 
among plants, such primary groups as Acotyledones, Monocotyledones, and Dicotyle- 
dones, under these or other names, others would separate the Gymnosperms from 
the Dicotyledones.2 
It appears to me, that this point in the classification of the living plants cannot 
1 Goppert, etc., q. a., p. 93. 
2 Ad. Brongniart, etc., q. a., p. 93. 112 
ESSAY ON CLASSIFICATION. 
Part I. 
be fully understood without a thorough acquaintance with the fossils and their 
distribution in the successive geological formations, and that this case exhibits 
one of the most striking examples of the influence classification may have upon 
our appreciation of the gradation of organized beings in the course of time. As 
long as Gymnosperms stand among Dicotyledones, no relation can be traced between 
the relative standing of living plants and the order of succession of their repre- 
sentatives in past ages. On the contrary, let the true affinity of Gymnosperms 
with Ferns, Equisetaceae, and especially with Lycopodiaceae be fully appreciated, and 
at once we see how the vegetable kingdom has been successively introduced upon 
earth, in an order which coincides with the relative position its primary divisions 
bear to one another, in respect to their rank, as determined by the complication 
of their structure. Truly, the Gymnosperms, with their imperfect flower, their open 
carpels, supporting their polyembryonic seeds in their axis, are more nearly allied 
to the anathic Aerophytes, with their innumerable spores, than to either the Mono- 
cotyledones or Dicotyledones; and, if the vegetable kingdom constitutes a graduated 
series beginning with Cryptoganes, followed by Gymnosperms, and ending with 
Monocotyledones and Dicotyledones, have we not in that series the most striking 
coincidence with the order of succession of Cryptogams in the oldest geological forma- 
tions, especially with the Ferns, Equisetaceae, and Lycopodiaceae of the Carboniferous 
period, followed by the Gymnosperms of the Trias and Jura and the Monocoty- 
ledones of the same formation and the late development of Dicotyledones? Here, 
as everywhere, there is but one order, one plan in nature. 
SECTION XXV. 
PARALLELISM BETWEEN THE GEOLOGICAL SUCCESSION OF ANIMALS AND THE EMBRYONIC 
GROWTH OF THEIR LIVING REPRESENTATIVES. 
Several authors have already alluded to the resemblance which exists between 
the young of some of the animals now living, and the fossil representatives of the 
same families in earlier periods.1 But these comparisons have, thus far, been traced 
only in isolated cases, and have not yet led to a conviction, that the character 
of the succession of organized beings in past ages, is such, in general, as to show 
1 Agassiz , (L.,) Poiss. foss., q. a., p. 54. - Em- 
bryonic Types, q. a., p. 11. - Twelve Leet., etc., p. 8. 
- Edwards, (II. Milne,) Considerations sur quel- 
ques principes relatifs a la Classification naturelle 
des animaux, An. Sc. Nat., 3e ser., 1844, 1 vol. 
p. 65. Chap. I. 
SUCCESSION AND DEVELOPMENT OF ANIMALS. 
113 
a remarkable agreement with the embryonic growth of animals; though the state 
of our knowledge in Embryology and Palaeontology justifies now such a conclusion. 
The facts most important to a proper appreciation of this point, have already been 
considered in the preceding paragraph, as far as they relate to the order of suc- 
cession of animals, when compared with the relative rank of their living repre- 
sentatives. In examining now the agreement between this succession and the phases 
of the embryonic growth of living animals, we may, therefore, take for granted, 
that the order of succession of their fossil representatives is sufficiently present 
to the mind of the reader, to afford a satisfactory basis of comparison. Too 
few Corals have been studied embryologically, to afford extensive means of com- 
parison ; yet so much is known, that the young polyp, when hatched, is an inde- 
pendent, simple animal, that it is afterwards incased in a cup, secreted by the foot of 
the actinoid embryo, which may be compared to the external wall of the Rugosa, 
and that the polyp gradually widens until it has reached its maximum diameter, 
prior to budding or dividing, while in ancient corals this stage of enlargement seems 
to last during their whole life, as, for example, in the Cyathophylloids. None of the 
ancient Corals form those large communities, composed of myriads of united individ- 
uals, so characteristic of our coral reefs; the more isolated and more independent 
character of the individual polyps of past ages presents a striking resemblance to 
the isolation of young corals, in all the living types. In no class is there, however, 
so much to learn still, as in Polypi, before the correspondence of their embryonic 
growth, and their succession in time, can be fully appreciated. In this connection 
I would also remark, that among the lower animals, it is rarely observed, that 
any one, even the highest type, represents in its metamorphoses all the stages of 
the lower types, neither in their development, nor in the order of their succession; 
and that frequently the knowledge of the embryology of several types of differ- 
ent standing, is required, to ascertain the connection of the whole series in both 
spheres. 
No class affords, as yet, a more complete and more beautiful evidence of the 
correspondence of their embryonic changes, with the successive appearance of their 
representatives in past ages, than the Echinoderms, thanks to the extensive and 
patient investigations of J. Muller upon the metamorphoses of these animals.2 Prior 
to the publication of his papers, the metamorphosis of the European Comatula alone 
was known. (See Sect. XVIII., p. 85.) This had already shown, that the early stages 
of growth of this Echinoderm exemplify the peduncated Crinoids of past ages. I have 
myself seen further, that the successive stages of the embryonic growth of Comatula 
typify, as it were, the principal forms of Crinoids which characterize the successive 
1 Milne-Edwards et Haime, q. a., p. 31. 
2 Muller, (J.,) Seven papers, q. a., p. 71. 114 
ESSAY ON CLASSIFICATION. 
Part I. 
geological formations; first, it recalls the Cistoids of the palaeozoic rocks, which are 
represented in its simple sphseroidal head, next the few-plated Platycrinoids of the 
Carboniferous period, next the Pentacrinoids of the Lias and Oolithe, with their whorls 
of cirrhi, and finally, when freed from its stem, it stands as the highest Crinoid, 
as the prominent type of the family, in the present period. The investigations of 
Midler upon the larva? of all the families of living Asterioids and Echinoids enable 
us to extend these comparisons to the higher Echinoderms also. The first point 
which strikes the observers in the facts ascertained by Muller, is the extraordinary 
similarity of so many larva?, of such different orders and different families as the 
Ophiuroids and Asterioids, the Echinoids proper and the Spatangoids, and even the 
Holothurioids, all of which end, of course, in reproducing their typical peculiarities. 
It is next very remarkable, that the more advanced larval state of Echinoids and 
Spatangoids should continue to show such great similarity, that a young Amphidetus 
hardly differs from a young Echinus.1 Finally, not to extend these remarks too far, 
I would only add, that these young Echinoids (Spatangus, as well as Echinus proper) 
have rather a general resemblance to Cidaris, on account of their large spines, 
than to Echinus proper. Now, these facts agree exactly with what is known 
of the successive appearance of Echinoids in past ages;2 their earliest representa- 
tives belong to the genera Diadema and Cidaris, next come true Echinoids, later 
only Spatangoids. When the embryology of the Clypeastroids is known, it will, 
no doubt, afford other links to connect a larger number of the members of this 
series. 
What is known of the embryology of Acephala, Gasteropoda, and Cephalopoda, 
affords but a few data for such comparisons. It is, nevertheless, worthy of remark, 
that while the young Lainellibraiicliwda are still in their embryonic stage of growth, 
they resemble, externally at least, Brachiopods3 more than their own parents, and 
the young shells of all Gasteropods4 known in their embryonic stage of growth, 
being all holostomate, recall the oldest types of that class. Unfortunately, nothing 
is yet known of the embryology of the Chambered Cephalopoda, which are the only 
ones found in the older geological formations, and the changes which the shield of 
the Dibranchiata undergoes have not yet been observed, so that no comparisons can 
be established between them and the Belemnites and other representatives of this 
order in the middle and more recent geological ages. 
Respecting Worms, our knowledge of the fossils is too fragmentary to lead to 
any conclusion, even should our information of the embryology of these animals 
1 Compare J. Muller's 1st paper, pl. III., with 
pls. IV.-VII., and with pls. VI. and VII., 4th paper. 
2 Agassiz, (L.,) Twelve Lectures, q. a., etc. p. 25. 
8 See the works, q. a., p. 73, note 1. 
4 See the works, q. a., p. 73, note 2, especially 
those relating to Nudibranchiata. Chap. I. 
SUCCESSION AND DEVELOPMENT OF ANIMALS. 
115 
be sufficient as a basis for similar comparisons. The class of Crustacea, on the 
contrary, is very instructive in this respect; but, to trace our comparisons through 
the whole series, it is necessary that we should consider simultaneously the em- 
bryonic growth of the higher Entomostraca, such as Limulus, and that of the highest 
order of the class,1 when it will appear, that as the former recall in early life 
the form and character of the Trilobites, so does the young Crab passing through 
the form of the Isopods, and that of the Macrouran Decapods, before it assumes its 
typical form as Brachyouran, recall the well-known succession of Crustacea through 
the geological middle ages and the tertiary periods to the present day. The early 
appearance of Scorpions, in the Carboniferous period, is probably also a fact to the 
point, if, as I have attempted to show, Araclmidians may be considered as exemplify- 
ing the chrysalis stage of development of Insects;2 but, for reasons already stated 
(Sect. XXIV.) it is hardly possible to take Insects into consideration in these inquiries. 
In my researches upon fossil Fishes,3 I have pointed out at length the embryonic 
character of the oldest fishes, but much remains to be done in that direction. 
The only fact of importance I have learned of late, is that the young Lepidosteus, 
long after it has been hatched, exhibits in the form of its tail, characters, thus 
far only known among the fossil fishes of the Devonian system.4 It is to be hoped, 
that the embryology of the Crocodile will throw some light upon the succession 
of the gigantic Reptiles of the middle geological ages, as I shall show, that the 
embryology of Turtles throws light upon the fossil Chelonians. It is already plain, 
that the embryonic changes of Batrachians coincide with what is known of their 
succession in past ages.5 The fossil Birds are too little known, and the fossil 
Mammalia6 do not extend through a sufficiently long series of geological formations 
to afford many striking points of comparison; yet, the characteristic peculiarities 
of their extinct genera exhibit everywhere indications, that their living representa- 
tives in early life resemble them more than they do their own parents. A minute 
comparison of a young elephant, with any mastodon, will show this most fully, 
not only in the peculiarities of their teeth, but even in the proportion of their 
limbs, their toes, etc. 
It may, therefore, be considered as a general fact, very likely to be more fully 
illustrated as investigations cover a wider ground, that the phases of development 
of all living animals correspond to the order of succession of their extinct repre- 
sentatives in past geological times. As far as this goes, the oldest representatives 
1 Agassiz, (L.,) Twelve Lectures, etc., p. 66. 
2 Classif. of Insects, q. a., p. 85. 
8 Poiss. fossiles, q. a., p. 54. 
4 Agassiz, (L.,) Lake Superior, etc., p. 254. 
5 See the works, q. a., p. 82, note 3. 
6 Cuv., Oss. foss., q. a.: also, Agassiz, (L.,) 
Zoological Character of Young Mammalia, Proc. Am. 
Ass. Adv. Sc., Cambridge, 1849, p. 85. 116 
ESSAY ON CLASSIFICATION. 
Part I. 
of every class may then be considered as embryonic types of their respective orders 
or families among the living. Pedunculated Crinoids are embryonic types of the 
Comatuloids, the oldest Echinoids embryonic representatives of the higher living 
families, Trilobites embryonic types of Entomostraca, the Oolitic Decapods embryonic 
types of our Crabs, the Heterocercal Ganoids embryonic types of the Lepidosteus, 
the Andrias Scheuchzeri an embryonic prototype of our Batrachians, the Zeuglodonts 
embryonic Sirenidae, the Mastodonts embryonic Elephants, etc. 
To appreciate, however, fully and correctly all these relations, it is further neces- 
sary to make a distinction between embryonic types in general, which represent 
in their whole organization early stages of growth of higher representatives of the 
same type, and embryonic features prevailing more or less extensively in the charac- 
ters of allied genera, as in the case of the Mastodon and Elephant, and what I 
would call hypembryonic types, in which embryonic features are developed to extremes 
in the further periods of growth, as, for instance, the wings of the Bats, which 
exhibit the embryonic character of a webbed hand, as all Mammalia have it at 
first, but here grown out and developed into an organ of flight, or assuming in 
other families the shape of a fin, as in the Whale, or the Sea-turtle, in which the 
close connection of the fingers is carried out to another extreme. 
Without entering into further details upon this subject, which will be fully 
illustrated in this work, enough has already been said to show, that the leading 
thought which runs through the succession of all organized beings in past ages, is 
manifested again in new combinations, in the phases of the development of the 
living representatives of these different types. It exhibits everywhere the working 
of the same creative Mind, through all times, and upon the whole surface of the 
globe. 
SECTION XXVI. 
PROPHETIC TYPES AMONG ANIMALS. 
We have seen in the preceding paragraph, how the embryonic conditions of 
higher representatives of certain types, called into existence at a later time, are 
typified, as it were, in representatives of the same types, which have existed at 
an earlier period. These relations, now they are satisfactorily known,- may also be 
considered as exemplifying, as it were, in the diversity of animals of an earlier 
period, the pattern upon which the phases of the development of other animals Chap. I. 
PROPHETIC TYPES AMONG ANIMALS. 
117 
of a later period were to be established. They appear now, like a prophecy in 
those earlier times, of an order of things not possible with the earlier combina- 
tions then prevailing in the animal kingdom, but exhibiting in a later period, in a 
striking manner, the antecedent considerations of every step in the gradation of 
animals. 
This is, however, by no means the only, nor even the most remarkable case, 
of such prophetic connections between facts of different dates. 
Recent investigations in Palmontology have led to the discovery of relations 
between animals of past ages and those now living, which were not even suspected 
by the founders of that science. It has, for instance, been noticed, that certain types 
which are frequently prominent among the representatives of past ages, combine 
in their structure, peculiarities which at later periods are only observed separately 
in different, distinct types. Sauriod Fishes before Reptiles, Pterodactyles before Birds, 
Ichthyosauri before Dolphins, etc. 
There are entire families, among the representatives of older periods, of nearly 
every class of animals, which, in the state of their perfect development exemplify 
such prophetic relations, and afford, within the limits of the animal kingdom, at 
least, the most unexpected evidence, that the plan of the whole creation had been 
maturely considered long before it was executed. Such types, I have for some 
time past, been in the habit of calling prophetic types. The Sauroid1 Fishes of the 
past geological ages, are an example of this kind. These Fishes, which have pre- 
ceded the appearance of Reptiles, present a combination of ichthyic and reptilian 
characters, not to be found in the true members of this class, which form its bulk 
at present. The Pterodactyles2 which have preceded the class of Birds, and the 
Ichthyosauri3 which have preceded the appearance of the Crustacea, are other exam- 
ples of such prophetic types. These cases suffice for the present, to show that 
there is a real difference between embryonic types and prophetic types. Embryonic 
types are in a measure also prophetic types, but they exemplify only the pecu- 
liarities of development of the higher representatives of their own types; while 
prophetic types exemplify structural combinations observed at a later period, in two 
or several distinct types, and are, moreover, not necessarily embryonic in their 
character, as for example, the Monkeys in comparison to Man; while they may be 
so, as in the case of the Pinnate, Plantigrade, and Digitigrade Carnivora, or still 
more so in the case of the pedunculated Crinoids.4 
Another combination is also frequently observed among animals, when a series 
exhibits such a succession as exemplifies a natural gradation, without immediate 
1 Agassiz, (L.,) Poiss. foss., vol. 2, part 2. 
2 Cuvier, (G.,) Oss. foss., vol. 5, p. 2. 
3 Cuvier, (G.,) Oss. foss., as q. a. 
4 See above, Sect. 25. 118 
ESSAY ON CLASSIFICATION. 
Part I. 
or necessary reference to either embryonic development or succession in time, as the 
Chambered Cephalopods. Such types I call progressive types) 
Again, a distinction ought to be made between prophetic types proper and 
what I would call synthetic types, though both are more or less blended in nature. 
Prophetic types proper, are those which in their structural complications lean towards 
other combinations fully realized in a later period, while synthetic .types, are those 
which combine, in a well balanced measure, features of several types occurring as 
distinct, only at a later time. Sauroid Fishes and Ichthyosauri are more distinctly 
synthetic than prophetic types, while Pterodactyles have more the character of 
prophetic types; so are also Echinocrinus with reference to Echini, Pentremites with 
reference to Asterioids, and Pentacrinus with reference to Comatula. Full illustra- 
tions of these different cases will yet be needed to render obvious the importance 
of such comparisons, and I shall not fail, in the course of this work, to present 
ample details upon this subject. Enough, however, has already been said to show, 
that the character of these relations among animals of past ages, compared with those 
of later periods or of the present day, exhibits more strikingly than any other 
feature of the animal kingdom, the thoughtful connection which unites all living 
beings, through all ages, into one great system, intimately linked together from 
beginning to end. 
SECTION XXVII. 
PARALLELISM BETAVEEN THE STRUCTURAL GRADATION OF ANIMALS AND THEIR 
EMBRYONIC GROWTH. 
So striking is the resemblance of the young of higher animals to the full-grown 
individuals of lower types, that it has been assumed by many writers that all the 
higher annuals pass, during the earlier stages of their growth, through phases cor- 
responding to the permanent constitution of the lower classes. These suppositions, 
the results of incomplete investigations, have even become the foundation of a 
system of philosophy of Nature, which represents all animals as the different degrees 
of development of a few primitive types.2 These views have been too generally 
circulated of late, in an anonymous work, entitled "Vestiges of Creation," to require 
1 Agassiz, (L.,) On the Difference between 
Progressive, Embryonic, and Prophetic Types, etc., 
Proc. Am. Ass. Adv. Sc., Cambridge, 1849, p. 432. 
2 Lamarck, q. a., p. 2G. - DuMaillet, (Pseu- 
don. Telliamed,) Entretiens d'un Pliilosophe indien 
avec un missionaire fran^ais, Amsterdam, 1748, 2 
vols. 8vo.-Oken, (Lor.,) Lehrbuch der Natur-Phi- 
losophie, q. a., p. 18. - The Vestiges of Creation, etc. Chap. I. 
RANK AND DEVELOPMENT OF ANIMALS. 
119 
further mention here. It has also been shown above (Sect. VIII.) that animals do 
not form such a simple series as would result from a successive development. 
There remains, therefore, only for us to show now within what limits the natural 
gradation which may be traced in the different types of the animal kingdom,1 cor- 
responds to the changes they undergo during their growth, having already considered 
the relations which exist between these metamorphoses and the successive appear- 
ance of animals upon earth, and between the latter and the structural gradation or 
relative standing of their living representatives. Our knowledge of the complication 
of structure of all animals is sufficiently advanced to enable us to select, almost at 
random, our examples of the correspondence between the structural gradation of 
animals and their embryonic growth, in all those classes the embryologic develop- 
ment of which has been sufficiently investigated. Yet, in order to show more 
distinctly how closely all the leading features of the animal kingdom are combined, 
whether we consider the complication of their structure, or their succession in time, 
or their embryonic development, I shall refer by preference to the same types 
which I have chosen before for the illustration of the other relations. 
Among Echinoderms, we find in the order of Crinoids the pedunculated types 
standing lowest,2 Comatulse highest, and it is well known that the young Comatula 
is a pedunculated Crinoid, which only becomes free in later life.3 J. Muller has 
shown that among the Echinoids, even the highest representatives, the Spatan- 
goids, differ but slightly in early youth from the Echinoids, and no zoologist 
can doubt that these are inferior to the former. Among Crustacea, Dana4 has 
insisted particularly upon the serial gradation which may be traced between the 
different types of Decapods, their order being naturally from the highest Bruchyoura, 
through the Anomoura, the Macroura, the Tetradecapods, etc., to the Entomostraca; 
the Macrouran character of the embryo of our Crabs has been fully illustrated 
by Rathke,5 in his beautiful investigations upon the embryology of Crustacea. I 
have further shown that the young of Macroura represents even Entomostraca 
forms, some of these young having been described as representatives of that 
order.6 The correspondence between the gradation of Insects and their embryonic 
growth, I have illustrated fully in a special paper.7 Similar comparisons have been 
made in the class of Fishes;8 among Reptiles, we find the most striking examples 
1 See the works quoted from p. 67-87, also Milne- 
Edwards, q. a., p. 112. - Thompson, Crinoids, q. a. 
2 Muller, (J.,) Ueber Pentacrinus Caput-Me- 
dusae, Berlin, 1833, 4to., Ak. d. Wiss. 
3 Forbes, (Ed.,) History of British Starfishes, 
London, 1851, 1 vol. 8vo., p. 10. 
4 Dana, q. a., p. 32. - Burmeister, Cirripeds, 
q. a., p. 79. - Thompson, q. a., p. 79. 
6 Rathke, q. a., p. 79. 
6 Twelve Lectures, etc., p. 67. 
7 Classification of Insects, q. a. 
8 Poissons fossiles, q. a. 120 
ESSAY ON CLASSIFICATION. 
Part I. 
of this kind among Batrachians1 (see, above, Sect. XII.); among Birds,2 the uniformly 
webbed foot, in all young, exhibits another correspondence between the young 
of higher orders and the permanent character of the lower ones. In the order 
of Carnivora, the Seals, the Plantigrades, and the Digitigrades exemplify the same 
coincidence between higher and higher representatives of the same types, and the 
embryonic changes through which the highest pass successively. 
No more complete evidence can be needed to show that there exists throughout 
the animal kingdom the closest correspondence between the gradation of their types 
and the embryonic changes their respective representatives exhibit throughout. And 
yet what genetic relation can there exist between the Pentacrinus of the West 
Indies and the Coinatulm, found in every sea; what between the embryos of Spatan- 
goids and those of Echinoids, and between the former and the adult Echinus; 
what between the larva of a Crab and our Lobsters; what between the Caterpillar 
of a Papilio and an adult Tinea, or an adult Sphinx; what between the Tadpole 
of a Toad and our Menobranchus; what between a young Dog and our Seals, 
unless it be the plan designed by an intelligent Creator? 
SECTION XXVIII. 
RELATIONS BETWEEN THE STRUCTURE, EMBRYONIC GROWTH, GEOLOGICAL SUCCESSION, AND 
THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 
4 
It requires unusual comprehensiveness of view to perceive the order prevailing 
in the geographical distribution of animals. We should, therefore, not wonder that 
this branch of Zoology is so far behind the other divisions of that science. Nor 
should we wonder at the fact that the geographical distribution of plants is so much 
better known than that of animals, when we consider how marked a feature the 
vegetable carpet which covers the surface of our globe is, when compared with the 
little show animals make, almost everywhere. And yet it will, perhaps, some day, 
be easier to understand the relations existing between the geographical distribution 
of animals and the other general relations prevailing among animals, because the 
range of structural differences is much greater among animals than among plants. 
Even now, some curious coincidences may be pointed out which go far to show 
that the geographical distribution of animals stands in direct relation to their rela- 
1 Twelve Lectures, etc., p. 8. 
2 Agassiz, (L.,) Lake Superior, etc., p. 194. Chap. I. GRADATION, GROWTH, SUCCESSION, DISTRIBUTION. 
121 
tive standing in their respective classes, and to the order of their succession in 
past geological ages, and more indirectly, also, to their embryonic growth. 
Almost every class has its tropical families, and these stand generally highest 
in their respective classes; or, when the contrary is the case, when they stand 
evidently upon a lower level, there is some prominent relation between them and 
the prevailing types of past ages. The class of Mammalia affords striking examples 
of these two kinds of connection. In the first place, the Quadrumana, which, next 
to Man, stand highest in their class, are all tropical animals; and it is worthy of 
remark, that the two highest types of Anthropoid Monkeys, the Orangs of Asia and 
the Chimpanzees of Western Africa bear, in the coloration of their skin, an addi- 
tional similarity to the races of Man inhabiting the same regions, the Orangs being 
yellowish red, as the Malays, and the Chimpanzee blackish, as the Negroes. The 
Pachyderms, on the contrary, stand low in their class, though chiefly tropical; but 
they constitute a group of animals prominent among the earliest representatives of 
that class in past ages. Among Chiroptera, the larger frugivorous representatives are 
essentially tropical; the more omnivorous, on the contrary, occur everywhere. Among 
Carnivora, the largest, most powerful, and also highest types, the Digitigrade, prevail 
in the tropics, while among the Plantigrades, the most powerful, the Bears, belong 
to the temperate and to the arctic zone, and the lowest, the Pinnate, are marine 
species of the temperate and arctic seas. Among Ruminants, we find the Giraffe 
and the Camels in the warmer zones, the others everywhere. In the class of Birds 
the gradation is not so obvious as in other classes, and yet the aquatic types form 
by far the largest representation of this class in temperate and cold regions, and 
are almost the only ones found in the arctic, while the higher land birds prevail in 
the warm regions. Among Reptiles, the Crocodilians are entirely tropical; the largest 
land Turtles are also only found in the tropics, and the aquatic representatives of 
this order, which are evidently inferior to their land kindred, extend much further 
north. The Rattlesnakes and Vipers extend further north and higher up the moun- 
tains than the Boas and the common harmless snakes. The same is true of Sala- 
manders and Tritons. The Sharks and Skates are most diversified in the tropics. It 
is also within the tropics that the most brilliant diurnal Lepidoptera are found, and 
this is the highest order of Insects. Among Crustacea the highest order, the Bra- 
chyoura, are most numerous in the torrid zone; but Dana has shown, what was not 
at all expected, that they nevertheless reach their highest perfection in the middle 
temperate regions.1 The Anomoura and Macroura, on the contrary, are nearly 
equally divided between the torrid and temperate zones; while the lower Tetrade- 
capods are far more numerous in extra tropical latitudes than in the tropical. The 
1 Dana, Crustacea, p. 1501. 122 
ESSAY ON CLASSIFICATION. 
Part I. 
Cephalopods are most diversified within the tropics; yet the Nautilus is a reminis- 
cence of past ages. Among Gasteropods, the Stromboids belong to the tropics; but 
among the lamellibranchiate Acephala, the Naiades, which seem to me to stand very 
high in their class, have their greatest development in the fresh waters of North 
America. The highest Echinoderms, the Holothurians and Spatangoids are most diver- 
sified within the tropics, while Echini, Starfishes, and Ophiurse extend to the arctics. 
The presence of Pentacrinus in the West Indies has undoubtedly reference to the 
prevalence of Crinoids in past ages. The Madrepores, the highest among the Acti- 
noid Polypi, are entirely tropical, while the highest Halcyonoids, the Renilla, Vere- 
tillum, and Pennatula, extend to the tropics and the temperate zone. 
Another interesting relation between the geographical distribution of animals and 
their representatives in past ages, is the absence of embryonic types in the warm 
regions. We find in the torrid zone no true representatives of the oldest geo- 
logical periods; Pentacrinus is not found before the Lias; among Cephalopods we 
find the Nautilus, but nothing like Orthoceras; Limulus, but nothing like Trilobites. 
This study of the relations between the geographical distribution of animals, and 
their relative standing, is rendered more difficult, and in many respects obscure, by 
the circumstance that entire types, characterized by peculiar structures, are so 
strangely limited in their range; and yet, even this shows how closely the geographi- 
cal distribution of animals is connected with their structure. Why New Holland 
should have no Monkeys, no Carnivora, no Ruminants, no Pachyderms, no Edentata, 
is not to be explained; but that this is the case, every zoologist knows, and is 
further aware, that the Marsupials1 of that continental island represent, as it were, 
the other orders of Mammalia, under their special structural modifications. New 
Holland appears thus as a continent with the characters of an older geological age. 
No one can fail, therefore, to perceive of how great an interest for Classification 
will be a more extensive knowledge of the geographical distribution of animals in 
general, and of the structural peculiarities exhibited by localized types. 
SECTION XXIX. 
MUTUAL DEPENDENCE OF THE ANIMAL AND VEGETABLE KINGDOMS. 
Though it had long been known, by the experiments of De Saussure, that the 
breathing process of animals and plants are very different, and that while the for- 
1 See Sect. 11. Chap. I. 
PARASITIC ANIMALS. 
123 
mer inhale atmospheric air, and exhale carbonic acid gas, the latter appropriate 
carbon and exhale oxygen, it was not until Dumas and Bousingault1 called partic- 
ularly the attention of naturalists to the subject, that it was fully understood how 
direct the dependence is of the animal and vegetable kingdoms one upon the other, 
in that respect, or rather how the one consumes what the other produces, and vice 
versa, thus tending to keep the balance which either of them would singly disturb 
to a certain degree. The common agricultural practice of manuring exhibits from 
another side the dependence of one kingdom upon the other: the undigested 
particles of the food of animals return to the ground, to fertilize it for fresh pro- 
duction.2 Again, the whole animal kingdom is either directly or indirectly dependent 
upon the vegetable kingdom for its sustenance, as the herbivorous animals afford 
the needful food for the carnivorous tribes. We are too far from the time when 
it could be supposed that Worms originated in the decay of fruits and other vege- 
table substances, to need here repetition of what is known respecting the repro- 
duction of these animals. Nor can it be necessary to show how preposterous the 
assumption would be that physical agents produced plants first, in order that from 
these, animals might spring forth. Who could have taught the physical agents to 
make the whole animal world dependent upon the vegetable kingdom ? 
On the contrary, such general facts as those above alluded to, show, more directly 
than any amount of special disconnected facts could do, the establishment of a well- 
regulated order of things, considered in advance; for they exhibit well-balanced 
conditions of existence, prepared long beforehand, such as only an intelligent being 
could ordain. 
SECTION XXX. 
PARASITIC ANIMALS AND PLANTS. 
However independent of each other some animals may appear, there are yet 
many which live only in the closest connection with their fellow-creatures, and 
which are known only as parasites upon or within them. Such are the intestinal 
Worms, and all the vermin of the skin.3 Among plants, the Mistletoe, Orobanche, 
1 Dumas, Legon sur la statique chimique des 
etres organises, Ann. Sc. Nat. 2de ser. vol. 6, p. 33; 
vol. 17, p. 122. 
2 Liebig, Agricultural Chemistry; Animal Chem- 
istry. 
8 See above, p. 76, notes 1 and 2, and p. 77, notes 
1 and 2 ; see also Rudolphi, (K. A.,) Entozoorum 
sive Vermium, etc., q. a., p. 31. - Bremser, (J. G.,) 
Ueber lebende Wiirmer im lebenden Menschen, 
Wien, 1819, 4to. - Dujardin, (F.,) Hist. Nat. des 
Helminthes, etc., q. a., p. 32. - Diesing, (C. M.,) 
Historia Vermium, etc., q. a., p. 32. 124 
ESSAY ON CLASSIFICATION. 
Part I. 
Rafflesia, and many Orchideae may be quoted as equally remarkable examples of 
parasitism. 
There exists the greatest variety of parasites among animals. It would take 
volumes to describe them and to write their history, for their relations to the 
animals and plants upon which they are dependent for their existence are quite 
as diversified as their form and their structure. 
It is important, however, to remark, at the outset, that these parasites do not 
constitute for themselves one great division of the animal kingdom. They belong, 
on the contrary, to all its branches; almost every class has its parasites, and in 
none do they represent one natural order. This fact is very significant, as it shows 
at once that parasitism is not based upon peculiar combinations of the leading 
structural features of the animal kingdom, but upon correlations of a more specific 
character. Nor is the degree of dependence of parasites upon other organized 
beings equally close. There are those which only dwell upon other animals, while 
others are so closely connected with them that they cannot subsist for any length 
of time out of the most intimate relation to the species in which they grow and 
multiply. Nor do these parasites live upon one class of animals; on the contrary, 
they are found in all of them. 
Among Vertebrata there are few parasites, properly speaking. None among 
Mammalia. Among Birds, a few species depend upon others to sit upon their 
eggs and hatch them, as the European Cuckoo, and the North American Cowbird. 
Among Fishes, some small Ophidiums (Fierasfers) penetrate into the cavity of the 
body of large Holothuriae in which they dwell.1 Echeneis attach themselves to 
other fishes, but only temporarily. Among Articulata, the number of parasites is 
largest. It seems to lie in the very character of this type, so remarkable for the 
outward display of their whole organization, to include the greatest variety of 
parasites. And it is really among them, that we observe the most extraordinary 
combinations of this singular mode of existence. 
Insects, in general, are more particularly dependent upon plants for their sus- 
tenance than herbivorous animals usually are, inasmuch as most of them are 
limited to particular plants for their whole life, such as the Plant-lice, the Coccus, 
the Gall Insects. In others, the larvae only are so limited to particular plants, while 
the larvae of others still, such as the Bots, grow and undergo their development 
under the skin or in the intestines, or in the nasal cavities of other animals. The 
Ichneumons lay their eggs in the larvae of other insects, upon which the young 
larvae prey until hatched. Among perfect Insects, there are those which live only 
in community with others, such as the Ant-Hill Insects, the Clavigers, the Clerus, 
1 See above, p. 74, note. Chap. I. 
PARASITIC ANIMALS. 
125 
and Bees. Different kinds of Ants live together, if not as parasites one upon another, 
at least in a kind of servitude. Other Insects live upon the bodies of warm 
blooded animals, such as the Fleas and Lice, and of these the number is legion. 
Some Hydrachnas are parasitic upon aquatic Mollusks.1 
Among Crustacea, there are Crabs constantly living in the shell of Mollusks, 
such as the Pinnotheres of the Oyster and Mussel. I have found other species upon 
Sea-Urchins, (Pinnotheres Melitt®, a new species, upon Melitta quinquefora). The 
Paguri take the shells of Mollusks to protect themselves; while a vast number of 
Amphipods live upon Fishes, attached to their gills, upon their tongue, or upon their 
skin, or upon Starfishes.2 The Cyamus Ceti lives upon the Whale. Some Cirripeds 
are parasites upon the Whales, others upon Corals. In the family of Lernaeans, 
the females are mostly parasites upon the gills or fins or upon the body of Fishes, 
while the males are free. 
Among Worms this mode of existence is still more frequent, and while some 
dwell only among Corals, entire families of others consist only of genuine parasites; 
but here again we find the most diversified relations; for, while some are con- 
stantly parasitic, others depend only for a certain period of their life upon other 
animals for their existence. The young Gordius is a free animal; it then creeps 
into the body of Insects, and leaves them again to propagate; the young Distoma 
lives free in the water as Cercaria, and spends the remainder of its life in other 
animals; the T®nia, on the contrary, is a parasite through life, and only its eggs 
pass from one animal into the other. But what is most extraordinary in this, 
as in many other intestinal Worms, is the fact, that while they undergo their first 
transformations in some kind of animals, they do not reach their complete develop- 
ment until they pass into the body of another higher type, being swallowed up by 
this while in the body of their first host. Such is the case with many Filariae, 
the Taeniae and Bothrocephali. These at first inhabit lower Fishes, and these Fishes 
being swallowed by Sharks or Water Birds, or Mice with their Worms being eaten 
up by Cats, the parasites living in them undergo their final transformation in the 
latter. Many Worms undertake extensive migrations through the bodies of other 
animals, before they reach the proper place for their final development.3 
1 Nitzsch, (Chr. L.,) Darstellung der Familien 
und Gattungen der Thierinsekten, Halle, 1818, 8vo. 
- Hayden, (C. v.,) Versuch einer systematischen 
Eintheilung der Acariden, Isis, 1826, p. 608.- 
Ratzenburg, (J. S. C.,) Die Ichneumonen der 
Forstinsekten, Berlin, 1844-52, 3 vols. 4to. fig.- 
Clark, (Br.,) Observations on the Genus Oestrus, 
Trans. Lin. Soc., HL, p. 289, fig. - Koch, (C. L.,) 
Die Pflanzen-Liiuse, Aphiden, Nurnberg, 1846, 8vo. 
fig. - Duges, (Ant.,) Recherches sur 1'ordre des 
Acariens, Ann. Sc. Nat., 2de ser., 1834, I., p. 5, II., 
p. 18, fig. 
2 I have found a new genus of this family upon 
Asterias Helianthoides. 
3 See above, p. 76, note 1; Siebold, Wanderung, 
etc., p. 77, note 1; Steenstrup, etc. 126 
ESSAY ON CLASSIFICATION. 
Part I. 
Among Mollusks, parasites are very few, if any can properly be called true 
parasites, as the males of some Cephalopods living upon their own females;1 as the 
Gasteropods growing buried in Corals,2 and the Lithodomus and a variety of Areas 
found in Corals. Among Radiata there are no parasites, properly speaking; some 
of them only attaching themselves by preference to certain plants, while the young 
of others remain connected with their parent, as in all Corals, and even among 
Crinoids, as in the Comatula of Charleston. 
In all these different cases, the chances that physical agents may have a share 
in producing such animals are still less than in the cases of independent animals, 
for here we have superadded to the very existence of these beings all the com- 
plicated circumstances of their peculiar mode of existence and their various con- 
nections with other animals. Now, if it can already be shown from the mere 
connections of independent animals, that external circumstances cannot be the cause 
of their existence, how much less could such an origin be ascribed to parasites! 
It is true, they have been supposed to originate in the body of the animals upon 
which they live. What then of those who enter the body of other animals at 
a somewhat advanced stage of growth, as the Gordius? Is it a freak of his? 
Or, what of those which only live upon other animals, such as lice; are they the 
product of the skin? Or, what of those which have to pass from the body of 
a lower into that of a higher animal, to undergo their final metamorphosis and 
in which this succession is normal? Was such an arrangement devised by the first 
animal, or imposed upon the first by the second, or devised by physical agents 
for the two ? Or, what of those in which the females only are parasites ? Had 
the two sexes a different origin ? Did perhaps the males and females originate 
in different ways ? 
I am at a loss to conceive how the origin of parasites can be ascribed to 
physical causes, unless, indeed, animals themselves be considered as physical causes, 
with reference to the parasites they nourish; and if so, why can they not get 
rid of them, as well as produce them, for it cannot be supposed, that all this 
is not done consciously, when parasites bear such close structural relations to the 
various types to which they belong ? 
The existence of parasitic animals belonging to so many different types of the 
animal as well as the vegetable kingdom, is a fact of deep meaning, which Man 
himself cannot too earnestly consider, and, while he may marvel at the fact, take 
it as a warning for himself, with reference to his boasted and yet legitimate hide- 
1 See above, p. 74, note 1, Kolliker, Muller, 
Verany and Vogt, etc. 
2 Ruppell, (Ed.,) Memoire sur le Magilus 
antiquus, Trans. Soc. Strasb., 1832, I., fig. Chap. I. 
COMBINATION OF RELATIONS. 
127 
pendence. All relations in nature are regulated by a superior wisdom. May we 
only learn in the end to conform, within the limits of our own sphere, to the 
laws assigned to each race I 
SECTION XXXI. 
COMBINATION IN TIME AND SPACE OF VARIOUS KINDS OF RELATIONS AMONG ANIMALS. 
It must occur to every reflecting mind, that the mutual relation and respective 
parallelism of so many structural, embryonic, geological, and geographical charac- 
teristics of the animal kingdom are the most conclusive proof, that they were 
ordained by a reflective mind, while they present at the same time the side of 
nature most accessible to our intelligence, when seeking to penetrate the relations 
between finite beings and the cause of their existence. 
The phenomena of the inorganic world are all simple, when compared to those 
of the organic world. There is not one of the great physical agents, electricity, 
magnetism, heat, light, or chemical affinity, which exhibits, in its sphere, as com- 
plicated phenomena as the simplest organized beings; and we need not look for 
the highest among the latter, to find them presenting the same physical phenomena 
as are manifested in the material world, besides those which are exclusively pecu- 
liar to them. When, then, organized beings include every thing the material world 
contains, and a great deal more that is peculiarly their own, how could they be 
produced by physical causes, and how can the physicists, acquainted with the laws 
of the material world, and who acknowledge that these laws must have been 
established at the beginning, overlook that a fortiori the more complicated laws 
which regulate the organic world, of the existence of which there is no trace for 
a long period upon the surface of the earth, must have been established, later 
and successively, at the time of the creation of the successive types of animals 
and plants ? 
Thus far, we have been considering chiefly the contrasts existing between the 
organic and inorganic worlds.1 At this stage of our investigation it may not be 
out of place to take a glance at some of the coincidences which may be traced 
between them, especially as they afford direct evidence that the physical world 
has been ordained in conformity with laws which obtain also among living beings, 
and disclose, in both spheres equally plainly, the workings of a reflective mind. 
1 Compare Sects. 24, 25, 26, 27, 28, 29, and 30. 128 
ESSAY ON CLASSIFICATION. 
Part I. 
It is well known, that the arrangement of the leaves in plants1 may be expressed 
by very simple series of fractions, all of which are gradual approximations to, or 
the natural means between J or j, which two fractions are themselves the maxi- 
mum and the minimum divergence between two single successive leaves. The 
normal series of fractions which expresses the various combinations most frequently 
observed among the leaves of plants, is as follows: J, j, j, f, T5^, /T, jf, y, etc. 
Now, upon comparing this arrangement of the leaves in plants with the revolu- 
tions of the members of our solar system, Peirce has discovered the most perfect 
identity between the fundamental laws which regulate both, as may be at once 
seen by the following diagram, in which the first column gives the names of the 
planets, the second column indicates the actual time of revolution of the successive 
planets, expressed in days, the third column the successive times of revolution of 
the planets, which are derived from the hypothesis that each time of revolution 
should have a ratio to those upon each side of it, which shall be one of the 
ratios of the law of phyllotaxis; and the fourth column, finally, gives the normal 
series of fractions expressing the law of the phyllotaxis. 
Neptune, . . 60,129 . . 62,000 
Uranus, . . . 30,687 . . . 31,000 . . . | 
Saturn, . . 10,759 . . 10,333 . . J 
Jupiter, . . . 4,333 . . . 4,133 . . . £ 
Asteroids, . . 1,200 to 2,000 . 1,550 . . g 
Mars, . . . 687 . . . 596 . . . 
Earth, . . 365 . . 366 . 1 
Venus, . . . 225 . . . 227 . • H J 
Mercury, . . 88 . . 87 . . 
In this series the Earth forms a break; but this apparent irregularity admits 
of an easy explanation. The fractions |, |, f, f, T6K, /T, etc., as expressing the 
position of successive leaves upon an axis, by the short way of ascent along the 
spiral, are identical, as far as their meaning is concerned, with the fractions express- 
ing these same positions, by the long way, namely, J, j, f, f, Jf, etc. 
Let us, therefore, repeat our diagram in another form, the third column giving 
the theoretical time of revolution. 
Neptune, . . g 62,000 . . 60,129 
" . | . 62,000 . . . 
Uranus, . . | 31,000 . . 30,687 
" . | . 15.500 . . . 
1 See the works quoted above, p. 18, note 3. Chap. I. 
COMBINATION OF RELATIONS. 
129 
Saturn, . . § 10,333 . . 10,759 
" . § . 6,889 . . . 
Jupiter, . . J 4,133 . . 4,333 
" . § . 2,480 . . . 
Asteroids, . . § 1,550 . . 1,200 
" . . . | . . . 968 .. . 
Mars, t85 596 .. . 687 
Earth, . . • A • . . 366 . . . 365 
Venus, . . || 227 . . . 225 
" . || . 140 .. . 
Mercury, 87 ... 88 
It appears from this table, that two intervals usually elapse between two suc- 
cessive planets, so that the normal order of actual fractions is |, |, f, J, etc., 
or the fractions by the short way in phyllotaxis, from which, however, the Earth 
is excluded, while it forms a member of the series by the long way. The explana- 
tion of this, suggested by Peirce, is that although the tendency to set off a planet 
is not sufficient at the end of a single interval, it becomes so strong near the 
end of the second interval, that the planet is found exterior to the limit of this 
second interval. Thus, Uranus is rather too far from the Sun relatively to Neptune, 
Saturn relatively to Uranus, and Jupiter relatively to Saturn, and the planets thus 
formed engross too large a proportionate share of material, and this is especially 
the case with Jupiter. Hence, when we come to the Asteroids, the disposition is 
so strong at the end of a single interval, that the outer Asteroid is but just within 
this interval, and the whole material of the Asteroids is dispersed in separate masses 
over a wide space, instead of being concentrated into a single planet. A conse- 
quence of this dispersion of the forming agents is, that a small proportionate 
material is absorbed into the Asteroids. Hence, Mars is ready for formation so 
far exterior to its true place, that when the next interval elapses the residual force 
becomes strong enough to form the Earth, after which the normal law is resumed 
without any further disturbance. Under this law, there can be no planet exterior 
to Neptune, but there may be one interior to Mercury. 
Let us now look back upon some of the leading features alluded to before, 
omitting the simpler relations of organized beings to the world around, or those of 
individuals to individuals, to consider only the different parallel series we have been 
comparing when showing that, in their respective great types, the phenomena of 
animal life correspond to one another, whether we compare their rank as deter- 
mined by structural complication with the phases of their growth, or with their 
succession in past geological ages; whether we compare this succession with their 
embryonic growth, or all these different relations with each other and with the geo- 130 
ESSAY ON CLASSIFICATION. 
Part I. 
graphical distribution of animals upon earth. The same series everywhere!1 These 
facts are true of all the great divisions of the animal kingdom, so far as we have 
pursued the investigation; and though, for want of materials, the train of evidence 
is incomplete in some instances, yet we have proof enough for the establishment 
of this law of a universal correspondence in all the leading features which binds 
all organized beings, of all times, into one great system, intellectually and intelligibly 
linked together, even where some links of the chain are missing. It requires con- 
siderable familiarity with the subject even to keep in mind the evidence, for, 
though yet imperfectly understood, it is the most brilliant result of the combined 
intellectual efforts of hundreds of investigators during half a century. The connec- 
tion, however, between the facts, it is easily seen, is only intellectual; and implies, 
therefore, the agency of Intellect as its first cause.2 
And if the power of thinking connectedly is the privilege of cultivated minds 
only; if the power of combining different thoughts, and of drawing from them new 
thoughts, is a still rarer privilege of a few superior minds; if the ability to trace 
simultaneously several trains of thought is such an extraordinary gift, that the few 
cases in which evidence of this kind has been presented have become a matter 
of historical record (Caesar dictating several letters at the same time), though they 
exhibit only the capacity of passing rapidly, in quick succession, from one topic to 
another, while keeping the connecting thread of several parallel thoughts: if all 
this is only possible for the highest intellectual powers, shall we by any false 
argumentation allow ourselves to deny the intervention of a Supreme Intellect in 
calling into existence combinations in nature, by the side of which, all human 
conceptions are child's play ? 
If I have succeeded, even very imperfectly, in showing that the various rela- 
tions observed between animals and the physical world, as well as between them- 
selves, exhibit thought, it follows, that the whole has an Intelligent Author, and it 
may not be out of place to attempt to point out, as far as possible, the difference 
there may be between Divine thinking and human thought. 
Taking nature as exhibiting thought for my guide, it appears to me, that while 
human thought is consecutive, Divine thought is simultaneous, embracing at the same 
time and for ever, in the past, the present, and the future, the most diversified 
relations among hundreds of thousands of organized beings, each of which may 
present complications again, which, to study and understand even imperfectly, as 
for instance, Man himself, Mankind has already spent thousands of years. And 
yet, all this has been done by one Mind, must be the work of one Mind only, of 
1 Compare all the preceding sections, where every 
topic is considered separately. 
2 Agassiz, (L.,) Contemplations of God in the 
Kosmos, Christian Examiner, January, 1851, Boston. Chap. I. 
COMBINATION OF RELATIONS. 
131 
Him before whom Man can only bow in grateful acknowledgment of the pre- 
rogatives he is allowed to enjoy in this world, not to speak of the promises of a 
future life. 
I have intentionally dismissed many points in my argument with mere questions, 
in order not to extend unduly a discussion which is after all only accessory to 
the plan of my work. I have felt justified in doing so because, from the point 
of view under which my subject is treated, those questions find a natural solution 
which must present itself to every reader. We know what the intellect of Man 
may originate, we know its creative power, its power of combination, of foresight, 
of analysis, of concentration; we are, therefore, prepared to recognize a similar 
action emanating from a Supreme Intelligence to a boundless extent. We need, 
therefore, not even attempt to show that such an Intellect may have originated all 
the Universe contains; it is enough to demonstrate, that the constitution of the 
physical world, and more particularly the organization of living beings in their connec- 
tion with the physical world prove, in general, the existence of a Supreme Being, 
as the Author of all things. The task of science is rather to investigate what has 
been done, to inquire, if possible, how it has been done, than to ask what is possible 
for the Deity, as we can know that only by what actually exists. To attack such 
a position, those who would deny the intervention in nature of a creative mind, 
must show, that the cause to which they refer the origin of finite beings is by 
its nature a possible cause, which cannot be denied of a being endowed with the 
attributes we recognize in God. Our task is therefore completed, as soon as we 
have proved his existence. It would, nevertheless, be highly desirable that every 
naturalist, who has arrived at similar conclusions, should go over the subject anew, 
from his point of view and with particular reference to the special field of his 
investigations; for so only can the whole evidence be brought out. 
I foresee already that some of the most striking illustrations may be drawn 
from the morphology of the vegetable kingdom, especially from the characteristic 
succession and systematical combination of different kinds of leaves in the forma- 
tion of the foliage and the flowers of so many plants, all of which end their 
development by the production of an endless variety of fruits. The inorganic world, 
considered in the same light, would not fail to exhibit also unexpected evidence 
of thought, in the character of the laws regulating the chemical combinations, the 
action of physical forces, the universal attraction, etc., etc. Even the history of 
human culture ought to be investigated from this point of view. But I must 
leave it to abler hands to discuss such topics. 132 
ESSAY ON CLASSIFICATION. 
Part I. 
SECTION XXXII. 
RECAPITULATION. 
In recapitulating the preceding statements, we may present the following con- 
clusions : - 
1st.1 The connection of all these known features of nature into one system ex- 
hibits thought, the most comprehensive thought, in limits transcending the highest 
wonted powers of man. 
2d. The simultaneous existence of the most diversified types under identical 
circumstances exhibits thought, the ability to adapt a great variety of structures to 
the most uniform conditions. 
3d. The repetition of similar types, under the most diversified circumstances, 
shows an immaterial connection between them; it exhibits thought, proving directly 
how completely the Creative Mind is independent of the influence of a material 
world. 
4th. The unity of plan in otherwise highly diversified types of animals, exhibits 
thought; it exhibits more immediately premeditation, for no plan could embrace such 
a diversity of beings, called into existence at such long intervals of time, unless it 
had been framed in the beginning with immediate reference to the end. 
5th. The correspondence, now generally known as special homologies, in the details 
of structure in animals otherwise entirely disconnected, down to the most minute 
peculiarities, exhibits thought, and more immediately the power of expressing a 
general proposition in an indefinite number of ways, equally complete in themselves, 
though differing in all their details. 
6th. The various degrees and different kinds of relationship among animals which 
can have no genealogical connection, exhibit thought, the power of combining dif- 
ferent categories into a permanent, harmonious whole, even though the material 
basis of this harmony be ever changing. 
7th. The simultaneous existence, in the earliest geological periods in which ani- 
mals existed at all, of representatives of all the great types of the animal kingdom, 
exhibits most especially thought, considerate thought, combining power, premeditation, 
prescience, omniscience. 
8th. The gradation based upon complications of structure which may be traced 
1 The numbers inscribed here correspond to the 
preceding sections, in the same order, so that the 
reader may at once refer back to the evidence, when 
needed. Chap. I. 
RECAPITULATION. 
133 
among animals built upon the same plan, exhibits thought, and especially the power 
of distributing harmoniously unequal gifts. 
9th. The distribution of some types over the most extensive range of the sur- 
face of the globe, while others are limited to particular geographical areas, and the 
various combinations of these types into zoological provinces of unequal extent, 
exhibit thought, a close control in the distribution of the earth's surface among 
its inhabitants. 
10th. The identity of structure of these types, notwithstanding their wide geo- 
graphical distribution, exhibits thought, that deep thought which, the more it is 
scrutinized, seems the less capable of being exhausted, though its meaning at the 
surface appears at once plain and intelligible to every one. 
11th. The community of structure in certain respects of animals otherwise en- 
tirely different, but living within the same geographical area, exhibits thought, and 
more particularly the power of adapting most diversified types with peculiar struc- 
tures to either identical or to different conditions of existence. 
12th. The connection, by series, of special structures observed in animals widely 
scattered over the surface of the globe, exhibits thought, unlimited comprehension, 
and more directly omnipresence of mind, and also prescience, as far as such series 
extend through a succession of geological ages. 
13th. The relation there is between the size of animals and their structure and 
form, exhibits thought; it shows that in nature the quantitative differences are as 
fixedly determined as the qualitative ones. 
14th. The independence, in the size of animals, of the mediums in which they 
live, exhibits thought, in establishing such close connection between elements so influ- 
ential in themselves and organized beings so little affected by the nature of these 
elements. 
15th. The permanence of specific peculiarities under every variety of external 
influences, during each geological period, and under the present state of things upon 
earth, exhibits thought: it shows, also, that limitation in time is an essential element 
of all finite beings, while eternity is an attribute of the Deity only. 
16th. The definite relations in which animals stand to the surrounding world, 
exhibit thought; for all animals living together stand respectively, on account of 
their very differences, in different relations to identical conditions of existence, in a 
manner which implies a considerate adaptation of their varied organization to these 
uniform conditions. 
17th. The relations in which individuals of the same species stand to one an- 
other, exhibit thought, and go far to prove the existence in all living beings of an 
immaterial, imperishable principle, similar to that which is generally conceded to man 
only. 134 
ESSAY ON CLASSIFICATION. 
Part I. 
18th. The limitation of the range of changes which animals undergo during their 
growth, exhibits thought; it shows most strikingly the independence of these changes 
of external influences, and the necessity that they should be determined by a 
power superior to these influences. 
19th. The unequal limitation in the average duration of the life of individuals 
in different species of animals, exhibits thought; for, however uniform or however 
diversified the conditions of existence may be under which animals live together, 
the average duration of life, in different species, is unequally limited. It points, there- 
fore, at a knowledge of time and space, and of the value of time, since the phases 
of life of different animals are apportioned according to the part they have to per- 
form upon the stage of the world. 
20th. The return to a definite norm of animals which multiply in various ways, 
exhibits thought. It shows how wide a cycle of modulations may be included in 
the same conception, without yet departing from a norm expressed more directly in 
other combinations. 
21st. The order of succession of the different types of animals and plants charac- 
teristic of the different geological epochs, exhibits thought. It shows, that while 
the material world is identical in itself in all ages, ever different types of organized 
beings are called into existence in successive periods. 
22d. The localization of some types of animals upon the same points of the sur- 
face of the globe, during several successive geological periods, exhibits thought, 
consecutive thought; the operations of a mind acting in conformity with a plan 
laid out beforehand and sustained for a long period. 
23d. The limitation of closely allied species to different geological periods, exhibits 
thought; it exhibits the power of sustaining nice distinctions, notwithstanding the 
interposition of great disturbances by physical revolutions. 
24th. The parallelism between the order of succession of animals and plants 
in geological times, and the gradation among their living representatives, exhibit 
thought; consecutive thought, superintending the whole development of nature from 
beginning to end, and disclosing throughout a gradual progress;, ending with the 
introduction of man at the head of the animal creation. 
25th. The parallelism between the order of succession of animals in geological 
times and the changes their living representatives undergo during their embryological 
growth, exhibits thought; the repetition of the same train of thoughts in the phases 
of growth of living animals and the successive appearance of their representatives 
in past ages. 
26th. The combination, in many extinct types, of characters which, in later ages, 
appear disconnected in different types, exhibits thought, prophetic thought, foresight; 
combinations of thought preceding their manifestation in living forms. Chap. I. 
RECAPITULATION. 
135 
27th. The parallelism between the gradation among animals and the changes 
they undergo during their growth, exhibits thought, as it discloses everywhere the 
most intimate connection between essential features of animals which have no 
necessary physical relation, and can, therefore, not be understood otherwise than 
as established by a thinking being. 
28th. The relations existing between these different series and the geographical 
distribution of animals, exhibit thought; they show the omnipresence of the Creator. 
29th. The mutual dependence of the animal and vegetable kingdoms for their 
maintenance, exhibits thought; it displays the care with which all conditions of 
existence, necessary to the maintenance of organized beings, have been balanced. 
30th. The dependence of some animals upon others or upon plants for their 
existence, exhibits thought; it shows to what degree the most complicated com- 
binations of structure and adaptation can be rendered independent of the physical 
conditions which surround them. 
We may sum up the results of this discussion, up to this point, in still fewer 
words: - 
All organized beings exhibit in themselves all those categories of structure and 
of existence upon which a natural system may be founded, in such a manner 
that, in tracing it, the human mind is only translating into human language the 
Divine thoughts expressed in nature in living realities. 
All these beings do not exist in consequence of the continued agency of physical 
causes, but have made their successive appearance upon earth by the immediate 
intervention of the Creator. As proof, I may sum up my argument in the fol- 
lowing manner: 
The products of what are commonly called physical agents are everywhere the 
same, (that is, upon the whole surface of the globe,) and have always been the 
same (that is, during all geological periods); while organized beings are everywhere 
different and have differed in all ages. Between two such series of phenomena 
there can be no causal or genetic connection. 
31st. The combination in time and space of all these thoughtful conceptions 
exhibits not only thought, it shows also premeditation, power, wisdom, great- 
ness, prescience, omniscience, providence. In one word, all these facts in their 
natural connection proclaim aloud the One God, whom man may know, adore, 
and love; and Natural History must, in good time, become the analysis of the 
thoughts of the Creator of the Universe, as manifested in the animal and vegetable 
kingdoms. 
It may appear strange that I should have included the preceding disquisition 
in that part of my work which is headed Classification. Yet, it has been done 136 
ESSAY ON CLASSIFICATION. 
Part 1. 
deliberately. In the beginning of this chapter, I have already stated that Classi- 
fication seems to me to rest upon too narrow a foundation when it is chiefly based 
upon structure. Animals are linked together as closely by their mode of develop- 
ment, by their relative standing in their respective classes, by the order in which 
they have made their appearance upon earth, by their geographical distribution, and 
generally by their connection with the world in which they live, as by their 
anatomy. All these relations should, therefore, be fully expressed in a natural 
classification; and though structure furnishes the most direct indication of some of 
these relations, always appreciable under every circumstance, other considerations 
should not be neglected, which may complete our insight into the general plan 
of creation. 
In characterizing the great branches of the animal kingdom, it is not enough 
to indicate the plan of their structure, in all its peculiarities; there are possibilities 
of execution which are at once suggested to the exclusion of others, and which 
should also be considered, and so fully analyzed, that the various modes in which 
such a plan may be carried out shall at once be made apparent. The range and 
character of the general homologies of each type should also be illustrated, as 
well as the general conditions of existence of its representatives. In characterizing 
classes, it ought to be shown why such groups constitute a class and not merely 
an order, or a family; and to do this satisfactorily, it is indispensable to trace the 
special homologies of all the systems of organs which are developed in them. It 
is not less important to ascertain the foundation of all the subordinate divisions 
of each class; to know how they differ, what constitutes orders, what families, what 
genera, and upon what characteristics species are based in every natural division. 
This we shall examine in the next chapter. CHAPTER SECOND. 
LEADING GROUPS OF THE EXISTING SYSTEMS OF ANIMALS. 
SECTION I. 
GREAT TYPES OR BRANCHES OF THE ANIMAL KINGDOM. 
The use of the terms types, classes, orders, families, genera, and species, in the 
systems of Zoology and Botany, is so universal, that it would be natural to suppose 
that their meaning and extent are well determined and generally understood; but 
this is so far from being the case that it may on the contrary be said, that there is 
no subject in Natural History respecting which there exists more uncertainty or 
a greater want of precision. Indeed, I have failed to find anywhere a definition 
of the character of most of the more comprehensive of these divisions, while the 
current views respecting genera and species are very conflicting. Under these cir- 
cumstances, it has appeared to me particularly desirable to inquire into the founda- 
tion of these distinctions, and to ascertain, if possible, how far they have a real 
existence. And, while I hope the results of this inquiry may be welcome and 
satisfactory, I am free to confess that it has cost me years of labor to arrive at 
a clear conception of their true character. 
It is such a universal fact in every sphere of intellectual activity, that prac- 
tice anticipates theory, that no philosopher should be surprised to find that zoologists 
have adopted instinctively natural groups, in the animal and vegetable kingdoms, 
even before the question of the character and of the very existence of such 
groups in nature was raised. Did not nations speak, understand, and write Greek, 
Latin, German, and Sanscrit, before it was even suspected that these languages, 
and so many others, were kindred ? Did not painters produce wonders with 
colors before the nature of light was understood ? Had not men been thinking 
about themselves and the world before logic and metaphysics were taught in schools ? 138 
ESSAY ON CLASSIFICATION. 
Part I. 
Why, then, should not observers of nature have appreciated rightly the relationship 
between animals or plants before getting a scientific clue to the classifications they 
were led to adopt as practical? 
Such considerations, above all others, have guided and encouraged me while I 
was seeking for the meaning of all these systems, so different one from the other in 
their details, and yet so similar in some of their general features. The history 
of our science shows how early some of the principles, which obtain to this day, 
have been acknowledged by all reflecting naturalists. Aristotle, for instance, already 
knew the principal differences which distinguish Vertebrata from all other animals, 
and his distinction of Enaima and Anaima1 corresponds exactly to that of Vertebrata 
and Invertebrata of Lamarck,2 or to that of Flesh- and Gut-Animals of Oken,3 or to that 
of Myeloneura and Ganglioneura of Ehrenberg;4 and one who is at all familiar 
with the progress of science at different periods can but smile at the claims to 
novelty or originality so frequently brought forward for views long before current 
among men. Here, for instance, is one and the same fact presented in different 
aspects; first, by Aristotle with reference to the character of the formative fluid, 
next by Lamarck with reference to the general frame, - for I will do Lamarck 
the justice to believe, that he did not unite the Invertebrata simply because they 
have no skeleton, but because of that something, which even Professor Owen fails 
to express,5 and which yet exists, the one cavity of the body in Invertebrata con- 
taining all organs, whilst Vertebrata have one distinct cavity for the centres of the 
nervous system, and another for the organs of the vegetative life. This acknowledg- 
ment is due to Lamarck as truly as it would be due to Aristotle not to accuse 
him of having denied the Invertebrata any fluid answering the office of the blood, 
though he calls them Anaima; for he knew nearly as well as we now know, 
that there moves a nutritive fluid in their body, though that information is 
generally denied him because he had no correct knowledge of the circulation of 
the blood. 
Again, when Oken speaks of Flesh-Animals he does not mean that Vertebrates 
consist of nothing but flesh, or that the Invertebrates have no muscular fibres; 
but he brings prominently before us the presence, in the former, of those masses, 
forming mainly the bulk of the body, which consist of flesh and bones as well 
as blood and nerves, and constitute another of the leading features distinguishing 
Vertebrata and Invertebrata. Ehrenberg presents the same relations between the 
same beings as expressed by their nervous system. If we now take the expressions 
1 Histor. Anim., Lib. I., Ch. 5 and 6. 
2 Anim. Vert., 2d edit., vol. 1, p. 313. 
8 Naturphilosophie, 3d edit., p. 400. 
4 Das Naturreich des Menschen; a diagram, upon 
a large sheet, folio. 
6 Comparat. Anat, of Inv., 2d edit., p. 11. Chap. II. 
BRANCHES OF THE ANIMAL KINGDOM. 
139 
of Aristotle, Lamarck, Oken, and Ehrenberg together, have we not, as characteristic 
of their systems, the very words by which every one distinguishes the most promi- 
nent features of the body of the higher animals, when speaking of blood relations, 
of blood and bones, or of having flesh and nerve ? 
Neither of these observers has probably been conscious of the identity of his 
classification with that of his predecessors; nor, indeed, should we consider either 
of them as superfluous, inasmuch as it makes prominent, features more or less differ- 
ent from those insisted upon by the others; nor ought any one to suppose that 
with all of them the field is exhausted, and that there is no more room for new 
systems upon that very first distinction among animals.1 As long as men inquire 
they will have opportunities to know more upon these topics than those who have 
gone before them, so inexhaustibly rich is nature in the innermost diversity of her 
treasures of beauty, order, and intelligence. 
So, instead of discarding all the systems which have thus far had little or no 
influence upon the progress of science, either because they are based upon prin- 
ciples not generally acknowledged or considered worthy of confidence, I have care- 
fully studied them with the view of ascertaining whatever there may be true in 
them, from the stand-point from which their authors have considered the animal 
kingdom; and I own that I have often derived more information from such a careful 
consideration than I had at first expected. 
It was not indeed by a lucky hit, nor by one of those unexpected apparitions 
which, like a revelation, suddenly break upon us and render at once clear and 
comprehensible what had been dark and almost inaccessible before, that I came to 
understand the meaning of those divisions called types, classes, orders, families, gen- 
era, and species, so long admitted in Natural History as the basis of every system, 
and yet so generally considered as mere artificial devices to facilitate our studies. 
For years I had been laboring under the impression that they are founded in 
nature, before I succeeded in finding out upon what principle they were really based. 
I soon perceived, however, that the greatest obstacle in the way of ascertaining 
their true significance lay in the discrepancies among different authors in their use 
and application of these terms. Different naturalists do not call by the same name 
groups of the same kind and the same extent: some call genera what others call 
subgenera; others call tribes, or even families, what are called genera by others; 
1 By way of an example, I would mention the 
mode of reproduction. The formation of the egg in 
Vertebrata; its origin, in all of them, in a more or 
less complicated Graafian vesicle, in which it is 
nursed ; the formation and development of the embryo 
up to a certain period, etc., etc., are so completely 
different from what is observed in any of the Inver- 
tebrata, that the animal kingdom, classified according 
to these facts, would again be divided into two great 
groups, corresponding to the Vertebrata and Inverte- 
brates of Lamarck, or the Flesh- and Gut-Animals of 
Oken, or the Eneima and Aneima of Aristotle, etc. 140 
ESSAY ON CLASSIFICATION. 
Part I. 
even the names of tribe and family have been applied by some to what others 
call sub-genera; some have called families what others have called orders; some 
consider as orders what others have considered as classes; and there are even genera 
of some authors which are considered as classes by others. Finally, in the number 
and limitation of these classes, as well as in the manner in which they are grouped 
together, under general heads, there is found the same diversity of opinion. It is, 
nevertheless, possible, that under these manifold names, so differently applied, groups 
may be designated which may be natural, even if their true relation to one another 
have thus far escaped our attention. 
It is already certain that most, if not all investigators agree in the limitation, 
of some groups at least, under whatever name they may call them, and however 
much they would blame one another for calling them so, or otherwise. I can there- 
fore no longer doubt that the controversy would be limited to definite ques- 
tions, if naturalists could only be led to an agreement respecting the real nature 
of each kind of groups. I am satisfied, indeed, that the most insuperable obstacle 
to any exact appreciation of this subject lies in the fact, that all naturalists, with- 
out exception, consider these divisions, under whatever name they may designate 
them, as strictly subordinate one to the other, in such a manner, that their differ- 
ence is only dependent upon their extent; the class being considered as the more 
comprehensive division, the order as the next extensive, the family as more limited, 
the genus as still more limited, and the species as the ultimate limitation in a 
natural arrangement of living beings, so that all these groups would differ only by 
the quantity of their characters, and not by the quality, as if the elements of 
structure in animals were all of the same kind; as if the form, for instance, was 
an organic element of the same kind as the complication of structure, and as if 
the degree of complication implied necessarily one plan of structure to the exclu- 
sion of another. I trust I shall presently be able to show that it is to a neglect 
of these considerations that we must ascribe the slow progress which has been 
made in the philosophy of classification. 
Were it possible to show that all these groups do not differ in quantity, and 
are not merely divisions of a wider or more limited range, but are based upon 
different categories of characters, genera would be called genera by all, whether 
they differ much or little one from the other, and so would families be called fam- 
ilies, orders be called orders, etc. Could, for instance, species be based upon absolute 
size, genera upon the structure of some external parts of the body, families upon 
the form of the body, orders upon the similarity of the internal structure, or the 
like, it is plain that there could not be two opinions respecting these groups in 
any class of the animal kingdom. But as the problem is not so simple in nature, 
it was not until after the most extensive investigations, that 1 seized the clue to Chap. II. 
BRANCHES OF THE ANIMAL KINGDOM. 
141 
guide me through this labyrinth. I knew, for instance, that though naturalists have 
been disputing, and are still disputing, about species and genera, they all distin- 
guished the things themselves in pretty much the same manner. What A would 
call a species, B called only a variety or a race; but then B might call a sub- 
genus the very same aggregate of individuals which A called a species; or what 
A called a genus was considered by B as a family or an order. Now it was this 
something called no matter how, for which I tried to find out characters which would 
lead all to call it by the same name; thus limiting the practical difficulty in the 
application of the name to a question of accuracy in the observations, and no longer 
allowing it to be an eternal contest about mere nomenclature. 
At this stage of my investigation it struck me, that the character of the writ- 
ings of eminent naturalists might throw some light upon the subject itself. There 
are authors, and among them some of the most celebrated contributors to our 
knowledge in Natural History, who never busied themselves with classification, or 
paid only a passing notice to this subject, whilst they are, by universal consent, 
considered as the most successful biographers of species; such are Buffon, Reau- 
mur, Roesel, Trembley, Smeathman, the two Hubers, Bewick, Wilson, Audubon, 
Naumann, etc. Others have applied themselves almost exclusively to the study of 
genera. Latreille is the most prominent zoologist of this stamp; whilst Linnaeus 
and Jussieu stand highest among botanists for their characteristics of genera, or at 
least for their early successful attempts at tracing the natural limits of genera. Bota- 
nists have thus far been more successful than zoologists in characterizing natural 
families, though Cuvier and Latreille have done a great deal in that same direction 
in Zoology, whilst Linnaeus was the first to introduce orders in the classification of 
animals. As to the higher groups, such as classes and types, and even the orders, 
we find again Cuvier leading the procession, in which have followed all the natu- 
ralists of this century. 
Now let us inquire what these men have done in particular to distinguish them- 
selves especially, either as biographers of species, or as characterizers of genera, of 
families, of orders, of classes, and of types. And should it appear that in each case 
they have been considering their subject from some particular point of view, it strikes 
me that what has been acknowledged unconsciously as constituting the particular emi- 
nence or distinction of these men, might very properly be proclaimed, with grate- 
ful consciousness of their services, as the characteristic of that kind of groups which 
each of them has most successfully illustrated; and I hope every unprejudiced natu- 
ralist will agree with me in this respect. 
As to the highest divisions of the animal kingdom, first introduced by Cuvier 
under the name of embranchements^ (and which we may well render by the good old 
English word branch^ he tells us himself that they are founded upon distinct plans 142 
ESSAY ON CLASSIFICATION. 
Part I. 
of structure, cast, as it were, into distinct moulds or forms.1 Now there can certainly 
be no reason why we should not all agree to designate as types or branches 
all such great divisions of the animal kingdom as are constituted upon a special 
plan,2 if we should find practically that such groups may be traced in nature. 
Those who may not see them may deny their existence; those who recognize 
them may vary in their estimation of their natural limits; but all can, for the 
greatest benefit of science, agree to call any group which seems to them to be 
founded upon a special plan of structure, a type or branch of the animal kingdom; 
and if there are still differences of opinion among naturalists respecting their limits, 
let the discussion upon this point be carried on with the understanding that types 
are to be characterized by different plans of structure, and not by special anatomical 
peculiarities. Let us avoid confounding the idea of plan with that of complication 
of structure, even though Cuvier himself has made this mistake here and there in 
his classification. 
The best evidence I can produce that the idea of distinct plans of structure 
is the true pivot upon which the natural limitation of the branches of the animal 
kingdom is ultimately to turn, lies in the fact that every great improvement, 
acknowledged by all as such, which these primary divisions have undergone, has 
consisted in the removal from among each, of such groups as had been placed 
with them from other considerations than those of a peculiar plan, or in conse- 
quence of a want of information respecting their true plan of structure. Let us 
examine this point within limits no longer controvertible. Neither Infusoria nor 
Intestinal Worms are any longer arranged by competent naturalists among Radiata. 
Why they have been removed, may be considered elsewhere; but it was certainly 
not because they were supposed to agree in the plan of their structure with the 
1 It would lead me too far were I to consider 
here the characteristics of the different kingdoms of 
Nature. I may, however, refer to the work of I. 
Geoffroy St. Hilaire, llistoire naturelie generale 
des regnes organiques, Paris, 1856, 8vo., who has dis- 
cussed this subject recently, though I must object to 
the admission of a distinct kingdom for Man alone. 
2 It is almost superfluous for me to mention here 
that the terms plan, ways and means, or manner in 
which a plan is carried out, complication of structure, 
form, details of structure, ultimate structure, relations 
of individuals, frequently used in the following pages, 
are taken in a somewhat different sense from their 
usual meaning, as is always necessary when new 
views are introduced in a science, and the adoption of 
old expressions, in a somewhat modified sense, is found 
preferable to framing new ones. I trust the value of 
the following discussion will be appreciated by its 
intrinsic merit, tested with a willingness to understand 
what has been my aim, and not altogether by the rela- 
tive degree of precision and clearness with which I 
may have expressed myself, as it is almost impossible, 
in a first attempt of this kind, to seize at once upon 
the form best adapted to carry conviction. I wish 
also to be understood as expressing my views more 
immediately with reference to the animal kingdom, 
as I do not feel quite competent to extend the inquiry 
and the discussion to the vegetable kingdom, though 
I have occasionally alluded to it, as far as my in- 
formation would permit. Chap. II. 
BRANCHES OF THE ANIMAL KINGDOM. 
143 
true Radiata, that Cuvier placed them in that division, but simply because he 
allowed himself to depart from his own principle, and to add another consideration, 
besides the plan of structure, as characteristic of Radiata, - the supposed absence of 
a nervous system, and the great simplicity of structure of these animals; - as if 
simplicity of execution had any necessary connection with the plan of structure. 
Another remarkable instance of the generally approved removal of a class from 
one of the types of Cuvier to another, was the transfer of the Cirripeds from 
among the Mollusks to the branch of Articulata. Imperfect knowledge of the plan 
of structure of these animals was here the cause of the mistake, which was cor- 
rected without any opposition, as soon as they became better known. 
From a comparison of what is stated here respecting the different plans of 
structure, characteristic of the primary divisions of the animal kingdom, with what 
I have to say below about classes and orders, it will appear more fully, that it 
is important to make a distinction between the plan of a structure and the man- 
ner in which that plan is carried out, or the degrees of its complication and its 
relative perfection or simplicity. But even after it is understood that the plan of 
structure should be the leading characteristic of these primary groups, it does not 
yet follow, without further examination, that the four great branches of the animal 
kingdom, first distinguished by Cuvier, are to be considered as the primary divisions 
which Nature points out as fundamental. It will still be necessary, by a careful 
and thorough investigation of the subject, to ascertain what these primary groups 
are; but we shall have gained one point with reference to our systems, - that what- 
ever these primary groups, founded upon different plans, which exist in nature, may 
be, when they are once defined, or whilst they are admitted as the temporary ex- 
pression of our present knowledge, they should be called the branches of the animal 
kingdom, whether they be the Vertebrata, Articulata, Mollusca, and Radiata of Cuvier, 
or the Artiozoaria, Actinozoaria, and Amorphozoaria of Blainville, or the Vertebrata 
and Invertebrata of Lamarck. The special inquiry into this point must be left for 
a special paper. I will only add that I am daily more satisfied, that, in their 
general outlines, the primary divisions of Cuvier are true to nature, and that never 
did a naturalist exhibit a clearer and deeper insight into the most general relations 
of animals than Cuvier, when he perceived, not only that these primary groups are 
founded upon differences in the plan of their structure, but also how they are 
essentially related to one another. 
Though the term type is generally employed to designate the great fundamental 
divisions of the animal kingdom, I shall not use it in future, but prefer for it the 
term branch of the animal kingdom, because the term type is employed in too 
many different acceptations, and quite as commonly to designate any group of any 
kind, or any peculiar modification of structure stamped with a distinct and marked 144 
ESSAY ON CLASSIFICATION. 
Part I. 
character, as to designate the primary divisions of the animal kingdom. We 
speak, for instance, of specific types, generic types, family types, ordinal types, 
classic types, and also of a typical structure. The use of the word type in this 
sense is so frequent on almost every page of our systematic works, in Zoology 
and in treatises of Comparative Anatomy, that it seems to me desirable, in order 
to avoid every possible equivocation in the designation of the most important great 
primary divisions among animals, to call them branches of the animal kingdom, 
rather than types. 
That, however, our systems are more true to nature than they are often sup- 
posed to be, seems to me to be proved by the gradual approximation of scientific 
men to each other, in their results, and in the forms by which they express those 
results. The idea which lies at the foundation of the great primary divisions 
of the animal kingdom is the most general conception possible in connection with 
the plan of a definite creation; these divisions are, therefore, the most comprehensive 
of all, and properly take the lead in a natural classification, as representing the 
first and broadest relations of the different natural groups of the animal kingdom, 
the general formula which they each obey. What we call branches expresses, in 
fact, a purely ideal connection between animals, the intellectual conception which 
unites them in the creative thought. It seems to me that the more we examine 
the true significance of this kind of groups, the more we shall be convinced that 
they are not founded upon material relations. The lesser divisions which succeed 
next are founded upon special qualifications of the plan, and differ one from the 
other by the character of these qualifications. Should it be found that the features 
in the animal kingdom which, next to the plan of structure, extend over the largest 
divisions, are those which determine their rank or respective standing, it would 
appear natural to consider the orders as the second most important category in the 
organization of animals. Experience, however, shows that this is not the case; 
that the manner in which the plan of structure is executed leads to the distinction 
of more extensive divisions (the classes) than those which are based upon the com- 
plication of structure (the orders). As a classification can be natural only as far as 
it expresses real relations observed in nature, it follows, therefore, that classes take 
the second position in a system, immediately under the branches. We shall see 
below that orders follow next, as they constitute naturally groups that are more 
comprehensive than families, and that we are not at liberty to invert their respec- 
tive position, nor to transfer the name of one of these divisions to the other, at 
our own pleasure, as so many naturalists are constantly doing. Chap. II. 
CLASSES OF ANIMALS. 
145 
SECTION II. 
CLASSES OF ANIMALS. 
Before Cuvier had shown that the whole animal kingdom is constructed upon 
four different plans of structure, classes were the highest groups acknowledged in 
the systems of Zoology, and naturalists very early understood upon what this kind 
of division should be founded, in order to be natural, even though in practice 
they did not always perceive the true value of the characters upon which they 
established their standard of relationship. Linnaeus, the first expounder of the 
system of animals, already distinguishes, by anatomical characters, the classes he 
has adopted, though very imperfectly; and ever since, systematic writers have aimed 
at drawing a more and more complete picture of the classes of animals, based 
upon a more or less extensive investigation of their structure. 
Structure, then, is the watchword for the recognition of classes, and an accurate 
knowledge of their anatomy the surest way to discover their natural limits. And 
yet, with this standard before them, naturalists have differed, and differ still greatly, 
in the limits they assign to classes, and in the number of them they adopt. It 
is really strange, that, applying apparently the same standard to the same objects, 
the results of their estimation should so greatly vary; and it was this fact which 
led me to look more closely into the matter, and to inquire whether, after all, 
the seeming unity of standard was not more a fancied than a real one. Structure 
may be considered from many points of view: first, with reference to the plan 
adopted in framing it; secondly, with reference to the work to be done by it, and 
to the ways and means employed in building it up; thirdly, with reference to the 
degrees of perfection or complication it exhibits, which may differ greatly, even 
though the plan be the same, and the ways and means employed in carrying out 
such a plan should not differ in the least; fourthly, with reference to the form 
of the whole structure and its parts, which bears no necessary relation, at all events 
no very close relation, to the degree of perfection of the structure, nor to the 
manner in which its plan is executed, nor to the plan itself, as a comparison 
between Bats and Birds, between Whales and Fishes, or between Holothurians and 
Worms, may easily show; fifthly and lastly, with reference to its last finish, to 
the execution of the details in the individual parts. 
It would not be difficult to show, that the differences which exist among 
naturalists in their limitation of classes have arisen from an indiscriminate con- 
sideration of the structure of animals, in all these different points of view, and an 146 
ESSAY ON CLASSIFICATION. 
Part I. 
equally indiscriminate application of the results obtained, to characterizing classes. 
Those who have not made a proper distinction between the plan of a structure 
and the manner in which that plan is actually executed, have either overlooked 
the importance of the great fundamental divisions of the animal kingdom, or they 
have unduly multiplied the number of these primary divisions, basing their dis- 
tinctions upon purely anatomical considerations, that is to say, not upon differences 
in the character of the general plan of structure, but upon the material develop- 
ment of that plan. Those, again, who have confounded the complication of the 
structure with the ways and means by which life is maintained through any given 
combination of systems of organs, have failed in establishing a proper difference 
between class and ordinal characters, and have again and again raised orders to 
the rank of classes. For we shall see presently, that natural orders must be based 
upon the different degrees of complication of structure, exhibited within the limits 
of the classes, while the classes themselves are characterized by the manner in 
which the plan of the type is carried out, that is to say, by the various com- 
binations of the systems of organs constituting the body of the representatives of 
any of the great types of the animal kingdom; or perhaps, still more distinctly, 
the classes are characterized by the different ways in which life is maintained, and 
the different means employed in establishing these ways. An example will suffice 
to show that this distinction implies a marked difference between class and ordinal 
characters. 
Let us compare the Polyps and Acalephs as two classes, without allowing our- 
selves to be troubled by the different limits assigned to them by different authors. 
Both are constructed upon the same plan, and belong, on that account, to the type 
of Radiata. In establishing this fact, we do not consider the actual structure of 
these animals, whether they have a nervous system or not, whether they have 
organs of senses or not, whether their muscles are striated or smooth, whether 
they have a solid frame or an entirely soft body, whether their alimentary cavity 
has only one opening or two opposite openings, whether it has glandular annexes 
or not, whether the digested food is distributed in the body one way or another, 
whether the undigested materials are rejected through the mouth or not, whether 
the sexes are distinct or not, whether they reproduce themselves only by eggs, or 
by budding also, whether they are simple or not: all we need know, in order to 
refer them to the branch of Radiata, is whether the plan of their structure exhibits 
a general radiated arrangement or not. But, when we would distinguish Polypi, 
Acalephs, and Echinoderms as classes, or rather, when we would ascertain what 
are the classes among Radiata, and how many there are, we must inquire into the 
manner in which this idea of radiation, which lies at the foundation of their plan 
of structure, is actually expressed in all the animals exhibiting such a plan, and Chap. II. 
CLASSES OF ANIMALS. 
147 
we find easily, that while in some (the Polypi) the body exhibits a large cavity, 
divided by radiating partitions into a number of chambers, into which hangs a sac, 
(the digestive cavity,) open below, so as to pour freely the digested food into 
the main cavity, whence it is circulated to and fro in all the chambers, by the 
agency of vibrating cilia; in others, (the Acalephs,) the body is plain and full 
not to be compared to a hollow sac, traversed only in its thickness by radiating 
tubes, which arise from a central cavity, (the digestive cavity,) without a free com- 
munication with one another for their whole length, etc., etc., while in others still, 
(the Echinoderms,) there is a tough or rigid envelope to the body, inclosing a large 
cavity in which are contained a variety of distinct systems of organs, etc. 
Without giving here a full description of these classes, I only wish to show, 
that what truly characterizes them, is not the complication of their structure, (for 
Hydroid Medusae are hardly more complicated in their structure than Polyps,) but 
the manner in which the plan of Radiata is carried out, the ways in which life 
is maintained in these animals, the means applied to this end; in one word, the 
combinations of their structural elements. But the moment we would discern 
what are the orders of these classes, these considerations no longer suffice; their 
structure has to be viewed in a different light; it is now the complication of 
these apparatus which may guide us. Actinarians and Halcyonarians among Polypi, 
as orders, differ, the first by having a larger and usually indefinite number of 
simple tentacles, an equally large number of internal partitions, etc., while in 
Halcyonarians the eight tentacles are lobed and complicated, and all the parts are 
combined in pairs, in definite numbers, etc., differences which establish a dis- 
tinct standing between them in their class, assigning the latter a higher rank than 
the former. 
It follows, then, from the preceding remarks, that classes are to be distinguished 
by the manner in which the plan of their type is executed, by the ways and 
means by which this is done, or, in other words, by the combinations of their 
structural elements, that is to say, by the combinations of the different systems of 
organs building up the body of their representatives. We need not consider here 
the various forms under which the structure is embodied, nor the ultimate details, 
nor the last finish which this structure may exhibit, as a moment's reflection will 
convince any one that neither form nor structural details can ever be characteristic 
of classes. 
There is another point to which I would call attention, respecting the charac- 
teristics of classes. These great divisions, so important in the study of the animal 
kingdom, that a knowledge of their essential features is rightly considered as the 
primary object of all investigations in comparative anatomy, are generally repre- 
sented as exhibiting each some essential modification of the type to which they 148 
ESSAY ON CLASSIFICATION. 
Part 1. 
belong. This view, again, I consider to be a mistaken appreciation of the facts, 
to which Cuvier has already called attention, though his warning has remained 
unnoticed.1 There is in reality no difference in the plan of animals belonging to 
different classes of the same branch. The plan of structure of Polypi is no more 
a modification of that of Acalephae, than that of Acalephae or Echinoderms is a 
modification of the plan of Polyps; the plan is exactly the same in all three; 
it may be represented by one simple diagram, and may be expressed in one single 
word, radiation; it is the manifestation of one distinct, characteristic idea. But 
this idea is exhibited in nature under the most different forms, and expressed in 
different ways, by the most diversified combinations of structural modifications and 
in the most varied relations. In the innumerable representatives of each branch 
of the animal kingdom, it is not the plan that differs, but the manner in which 
this plan is executed. In the same manner as the variations played by a skilful 
artist upon the simplest tune are not modifications of the tune itself, but only 
different expressions of the same fundamental harmony, just so are neither the classes, 
nor the orders, nor the families, nor the genera, nor the species of any great type, 
modifications of its plan, but only its different expressions, the different ways in 
which the fundamental thought embodied in it is manifested in a variety of living 
beings. 
In studying the characteristics of classes we have to deal with structural features, 
while in investigating their relations to the branches of the animal kingdom to 
which they belong, we have only to consider the general plan, the framework, 
as it were, of that structure, not the structure itself. This distinction leads to 
an important practical result. Since, in the beginning of this century, naturalists 
have begun, under the lead of the German physiophilosophers, to compare more 
closely the structure of the different classes of the animal kingdom, points of 
resemblance have been noticed between them which had entirely escaped the atten- 
tion of earlier investigators, structural modifications have been identified, which, at 
first, seemed to exhibit no similarity, so much so, that step by step these com- 
parisons have been extended over the whole animal kingdom, and it has been 
asserted, that, whatever may be the apparent differences in the organization of ani- 
mals, they should be considered as constructed of parts essentially identical. This 
assumed identity of structure has been called homology.2 But the progress of 
science is gradually restricting these comparisons within narrower limits, and it 
appears now, that the structure of animals is homologous only as far as they belong 
to the same branch, so much so, that the study of homologies is likely to afford 
one of the most trustworthy means of testing the natural limits of any of the 
1 Cuvier, Regn. An., 2d edit., p. 48. 
2 See Chap. I., Sect. 5. Chap. II. 
CLASSES OF ANIMALS. 
149 
great types of the animal kingdom. While, however, homologies show the close 
similarity of apparently different structures and the perfect identity of their plan, 
within the same branches of the animal kingdom, yet, they daily exhibit more 
and more striking differences, both in plan and structure, between the branches 
themselves, leading to the suspicion that systems of organs which are generally 
considered as identical in different types, will, in the end, prove essentially different, 
as, for instance, the so-called gills in Fishes, Crustacea, and Mollusks. 
It requires no great penetration to see already that the gills of Crustacea are 
homologous with the tracheae of Insects and the so-called lungs of certain spiders, in 
the same manner as the gills of aquatic Mollusks are homologous with the so-called 
lungs of our air-breathing snails and slugs. Now, until it can be shown that all 
these different respiratory organs are truly homologous, I hold it to be more natural 
to consider the system of respiratory organs in Mollusks, in Articulates, and in Verte- 
brates, as essentially different among themselves, though homologous within the limits 
of each type; and this remark I would extend to all their systems of organs, to their 
solid frame, to their nervous system, to their muscular system, to their digestive 
apparatus, to their circulation, and to their reproductive organs, etc. It would not 
be difficult to show now that the alimentary canal with its glandular appendages, 
in Vertebrata, is formed in an entirely different way from that of Articulates or 
Mollusks, and that it cannot be considered as homologous in all these types. And 
if this be true, we must expect soon an entire reform of our methods of illustrating 
comparative anatomy. 
Finally, it ought to be remembered, in connection with the study of classes as 
well as that of other groups, that the amount of difference existing between any 
two divisions is nowhere the same. Some features in nature seem to be insisted 
upon with more tenacity than others, to be repeated more frequently and more 
widely, and to be impressed upon a larger number of representatives. This 
unequal weight of different groups, so evident everywhere in the animal kingdom, 
ought to make us more cautious in estimating their natural limits, and prevent us 
from assigning an undue value to the differences observed between living beings, 
never overrating apparently great discrepancies, nor underrating seemingly trifling 
variations. The right path, however, can only be ascertained by extensive inves- 
tigations, made with special reference to this point. 
Everybody must know that the males and females of some species differ much 
more one from the other than many species do, and yet the amount of difference 
observed between species is constantly urged, even without a preliminary investi- 
gation, as an argument for distinguishing them. These differences, moreover, are 
not only quantitative, they are to a still greater extent also qualitative. In the 150 
ESSAY ON CLASSIFICATION. 
Part I. 
same manner do genera differ more or less one from the other, even in the same 
family; and such inequality, and not an equable apportionment, is the norm through- 
out nature. In classes, it is not only exhibited in the variety of their forms, but 
also, to an extraordinary extent, in their numbers, as, for instance, in the class of 
Insects compared to that of Worms or Crustacea. The primary divisions of the ani- 
mal kingdom differ in the same manner one from the other. Articulata are by far 
the most numerous branch of the whole animal kingdom; their number exceeding 
greatly that of all other animals put together. Such facts are in themselves sufficient 
to show how artificial classifications must be which admit only the same number 
and the same kind of divisions for all the types of the animal kingdom. 
SECTION III. 
ORDERS AMONG ANIMALS. 
Great as is the discrepancy between naturalists respecting the number and limits 
of classes in the animal kingdom, their disagreement in regard to orders and families 
is yet far greater. These conflicting views, however, do not in the least shake 
my confidence in the existence of fixed relations between animals, determined by 
thoughtful considerations. I would as soon cease to believe in the existence of 
one God, because men worship Him in so many different ways, or because they 
even worship gods of their own making, as distrust the evidence of my own senses 
respecting the existence of a preestablished and duly considered system in nature, 
the arrangement of which preceded the creation of all things that exist. 
From the manner in which orders are generally characterized and introduced 
into our systems, it would seem as if this kind of groups were interchangeable 
with families. Most botanists make no difference even between orders and families, 
and take almost universally the terms as mere synonyms. Zoologists have more 
extensively admitted a difference between them, but while some consider the orders 
as superior, others place families higher; others admit orders without at the same 
time distinguishing families, and vice versa introduce families into their classification 
without admitting orders; others still admit tribes as intermediate groups between 
orders and families. A glance at any general work on Zoology or Botany may 
satisfy the student how utterly arbitrary the systems are in this respect. The 
Rtyne animal of Cuvier exhibits even the unaccountable feature, that while orders Chap. II. 
ORDERS AMONG ANIMALS. 
151 
and families are introduced in some classes,1 only orders are noticed in others,2 
and even some exhibit only a succession of genera under the head of their class, 
without any further grouping among them into orders or families.3 Other classi- 
fications exhibit the most pedantic uniformity of a regular succession in each class, 
of sub-classes, orders, sub-orders, families, sub-families, tribes, sub-tribes, genera, sub- 
genera, divisions, sections, and sub-divisions, sub-sections, etc., but bear upon their 
face, that they are made to suit preconceived ideas of regularity and symmetry in 
the system, and that they are by no means studied from nature. 
To find out the natural characters of orders from that which really exists in 
nature, I have considered attentively the different systems of Zoology in wdiich 
orders are admitted and apparently considered with more care than elsewhere, and 
in particular the Sy sterna Natures of Linnaeus, who first introduced in Zoology that 
kind of groups, and the works of Cuvier, in which orders are frequently charac- 
terized with unusual precision, and it has appeared to me that the leading idea 
prevailing everywhere respecting orders, where these groups are not admitted at 
random, is that of a definite rank among them, the desire to determine the rela- 
tive standing of these divisions, to ascertain their relative superiority or inferiority, 
as the name order, adopted to designate them, already implies. The first order 
in the first class of the animal kingdom, according to the classification of Linnaeus, 
is called by him Primates, expressing, no doubt, his conviction that these beings, 
among which Man is included, rank uppermost in their class. Blainville uses here 
and there the expression of " degrees of organization," to designate orders. It is 
true Lamarck uses the same expression to designate classes. We find, therefore, 
here as everywhere, the same vagueness in the definition of the different kinds of 
groups adopted in our systems. But if we would give up any arbitrary use of 
these terms, and assign to them a definite scientific meaning, it seems to me most 
natural, and in accordance with the practice of the most successful investigators 
of the animal kingdom, to call orders such divisions as are characterized by differ- 
ent degrees of complication of their structure, within the limits of the classes. 
As such I would consider, for instance, the Actinoids and Halcyonoids in the class 
of Polypi, as circumscribed by Dana; the Hydroids, the Discophone, and the Cte- 
1 In the classes Mammalia, Birds, Reptiles, and 
Fishes, Cuvier distinguishes mostly families as well 
as orders. In the class of Mammalia, some orders 
number no families, whilst others are divided into 
tribes instead of families. In the class of Gasteropods, 
Annelids, Intestinal Worms, and Polyps, some of the 
orders only are divided into families, while the larger 
number are not. 
2 The classes Echinoderms, Acalephs, and Infu- 
soria, are divided into orders, but without families. 
3 Such are his classes of Cephalopods, Pteropods, 
Brachiopods, and Cirripeds (Cirrhopods.) Of the Ce- 
phalopods, he says, however, they constitute but one 
order (Regn. An. vol. 3, p. 11), and, p. 22, he calls 
them a family, and yet he distinguishes them as a 
class, p. 8. 152 
ESSAY ON CLASSIFICATION. 
Part I. 
noids among Acalephs; the Crinoids, Asterioids, Echinoids, and Holothuriae among 
Echinoderms; the Bryozoa, Brachiopods, Tunicata, Lamellibranchiata among Acephala; 
the Branchifera and Pulmonata among Gasteropods; the Ophidians, the Saurians, 
and the Chelonians among Reptiles; the Ichthyoids and the Anoura among Amphi- 
bians, etc. 
Having shown in the preceding paragraph that classes rank next to branches, 
it would be proper I should show here that orders are natural groups which stand 
above families in their respective classes; but for obvious reasons I have deferred 
this discussion to the following paragraph, which relates to families, as it will be 
easier for me to show what is the respective relation of these two kinds of groups 
after their special character has been duly considered. 
From the preceding remarks respecting orders it might be inferred that I deny 
all gradation among all other groups, or that I assume that orders constitute neces- 
sarily one simple series in each class. Far from asserting any such thing, I hold 
on the contrary, that neither is necessarily the case. But to explain fully my 
views upon this point, I must introduce here some other considerations. It will 
be obvious, from what has already been said, (and the further illustration of this 
subject will only go to show to what extent this is true,) that there exists an 
unquestionable hierarchy between the different kinds of groups admitted in our 
systems, based upon the different kinds of relationship observed among animals, 
that branches are the most comprehensive divisions, including each several classes, 
that orders are subdivisions of the classes, families subdivisions of orders, genera 
subdivisions of families, and species subdivisions of the genera; but not in the 
sense that each type should necessarily include the same number of classes, nor 
even necessarily several classes, as this must depend upon the manner in which 
the type is carried out. A class, again, might contain no orders,1 if its represent- 
atives presented no different degrees characterized by the greater or less compli- 
cation of their structure; or it may contain many, or few, as these gradations are 
more or less numerous and well marked; but as the representatives of any and 
every class have of necessity a definite form, each class must contain at least one 
family, or many families, indeed, as many as there are systems of forms under 
which its representatives may be combined, if form can be shown to be charac- 
teristic of families. The same is the case with genera and species; and nothing 
is more remote from the truth than the idea that a genus is better defined in 
proportion as it contains a greater number of species, or that it may be necessary 
to know several species of a genus before its existence can be fully ascertained. 
A genus may be more satisfactorily characterized, its peculiarity more fully ascer- 
1 See Chap. I. Sect. 1. Chap. II. 
ORDERS AMONG ANIMALS. 
153 
tained, its limits better defined, when we know all its representatives; but I am 
satisfied that any natural genus may be at least pointed out, however numerous 
its species may be, from the examination of any single one of them. Moreover, 
the number of genera, both in the animal and vegetable kingdom, which contain 
but a single species, is so great that it is a matter of necessity in all these cases 
to ascertain their generic characteristics from that one species. Again, such species 
require to be characterized with as much precision, and their specific characters to 
be described with as much minuteness, as if a host of them, but not yet known, 
existed besides. It is a very objectionable practice among zoologists and botanists, 
to remain satisfied in such cases with characterizing the genus, and perhaps to 
believe, what some writers have actually stated distinctly, that in such cases generic 
and specific characters are identical. 
Such being the natural relations and the subordination of types, classes, orders, 
families, genera, and species, I believe, nevertheless, that neither types, nor classes, 
(orders of course not at all,) nor families, nor genera, nor species have the same 
standing when compared among themselves. But this does not in the least inter- 
fere with the prominent features of orders, for the relative standing of types, or 
classes, or families, or genera, or species does not depend upon the degrees of 
complication of their structures as that of orders does, but upon other features, 
as I will now show. The four great types or branches of the animal kingdom, 
characterized as they are by four different plans of structure, will each stand higher 
or lower, as the plan itself bears a higher or lower character, and that this may 
be the case we need only compare Vertebrata and Radiata.1 The different classes 
of one type will stand higher or lower, as the ways in which and the means with 
which, the plan of the type to which they belong is carried out, are of a higher 
or lower nature. Orders in any or all classes are of course higher or lower 
according to the degree of perfection of their representatives, or according to the 
complication or simplicity of their structure. Families may stand higher or lower 
as the peculiarities of their form are determined by modifications of more or less 
important systems of organs. Genera may stand higher or lower as the structural 
peculiarities of the parts constituting the generic characteristics exhibit a higher 
or lower grade of development. Species, lastly, may stand one above the other, 
in the same genus, according to the character of their relations to the surrounding 
world, or that of their representatives to one another. These remarks must 
make it plain that the respective rank of groups of the same kind among them- 
selves must be determined by the superior or inferior grade of those features upon 
1 I must leave out the details of such comparisons, 
as a mere mention of the point suffices to suggest them; 
moreover, any text-book of comparative anatomy 
may furnish the complete evidence to that effect. 154 
ESSAY ON CLASSIFICATION. 
Part I. 
which they are themselves founded; while orders alone are strictly defined by the 
natural degrees of structural complications exhibited within the limits of the 
classes. 
As to the question, whether orders constitute necessarily one simple series in 
their respective classes, I would say, that this must depend upon the character 
of the class itself, or the manner in which the plan of the type is carried out 
within the limits of the class. If the class is homogeneous, that is, if it is not 
primarily subdivided into sub-classes, the orders will, of course, form a single series; 
but if some of its organic systems are developed in a different way from the others, 
there may be one or several parallel series, each subdivided into gradated orders. 
This can, of course, only be determined by a much more minute study of the 
characteristics of classes than has been made thus far, and mere guesses at such 
an internal arrangement of the classes into series, as those proposed by Kaup or 
Fitzinger, can only be considered as the first attempts towards an estimation of 
the relative value of the intermediate divisions which may exist between the classes 
and their orders. 
Oken and the physiophilosophers generally have taken a different view of orders. 
Their idea is, that orders represent, in their respective classes, the characteristic 
features of the other types of the animal kingdom. As Oken's Intestinal or Gelatin- 
ous animals are characterized by a single system of organs, the intestine, they 
contain no distinct orders, but each class has three tribes, corresponding to the 
three classes of this type, which are Infusoria, Polypi, and Acalephs. The tribes of 
the class of Infusoria, are Infusoria proper, Polypoid Infusoria, and Acalephoid Infu- 
soria; the tribes of the class of Polypi, are Infusorial Polypi, Polypi proper, and 
Acalephoid Polypi; the tribes of the class Acalephs, are Infusorial Acalephs, Polypoid 
Acalephs, and Acalephs proper. But the classes of Mollusks which are said to be 
characterized by two systems of organs, the intestine and the vascular system, 
contain each two orders, one corresponding to the Intestinal animals, the other to 
the type of Mollusks, and so Acephala are divided into the order of Gelatinous 
Acephala and that of Molluscoid Acephala, and the Gasteropods and Cephalopods 
in the same manner into two orders each. The Articulata are considered as repre- 
senting three systems of organs, the intestinal, the vascular, and the respiratory 
systems; hence their classes are divided each into three orders. For instance, the 
Worms contain an order of Gelatinous Worms, one of Molluscoid Worms, one of 
Annulate Worms, and the same orders are adopted for Crustacea and Insects. Verte- 
brata are said to represent five systems, the three lower ones being the intestine, the 
vessels, and the respiratory organs, the two higher the flesh (that is, bones, muscles, 
and nerves) and the organs of senses; hence, five orders in each class of this 
type, as, for example, Gelatinous Fishes, Molluscoid Fishes, Entomoid Fishes, Carnal Chap. II. 
FAMILIES. 
155 
Fishes, and Sensual Fishes, and so also in the classes of Reptiles, Birds, and 
Mammalia.1 
I have entered into so many details upon these vagaries of the distinguished 
German philosopher, because these views, however crude, have undoubtedly been 
suggested by a feature of the animal kingdom, which has thus far been too little 
studied: I mean the analogies which exist among animals, besides their true affinities, 
and which cross and blend, under modifications of strictly homological structures, 
other characters which are only analogical. But it seems to me that the subject 
of analogies is too little known, the facts bearing upon this kind of relationship 
being still too obscure, to be taken as the basis of such important groups in the 
animal kingdom as the orders are, and I would insist upon considering the complica- 
tion or gradation of structure as the feature which should regulate their limitation, 
if under order we are to understand natural groups expressing the rank, the relative 
standing, the superiority or inferiority of animals in their respective classes. Of 
course, groups thus characterized cannot be considered as mere modifications of the 
classes, being founded upon a special category of features. 
SECTION IV. 
FAMILIES. 
Nothing is more indefinite than the idea of form, as applied by systematic 
writers, in characterizing animals. Here, it means a system of the most different 
figures having a common character, as, for instance, when it is said of Zoophytes 
that they have a radiated form; there, it indicates any outline which circumscribes 
the body of animals, when, for instance, animal forms are alluded to in general, 
instead of designating them simply as animals; here, again, it means the special 
figure of some individual species. There is in fact no group of the animal king- 
dom, however extensive or however limited, from the branches down to the species, 
in which the form is not occasionally alluded to as characteristic. Speaking of Articu- 
lates, C. E. v. Baer characterizes them as the type with elongated forms; Mollusks 
are to him the type with massive forms; Radiates that with peripheric symmetry; 
Vertebrates that with double symmetry, evidently taking their form in its widest 
sense as expressing the most general relations of the different dimensions of the 
1 See further developments upon this subject in 
Oken's Naturphilosophie, and in his Allgemeine 
Naturgeschichte, vol. 4, p. 582. Compare also the 
following chapter. 156 
ESSAY ON CLASSIFICATION. 
Part I. 
body to one another. Cuvier speaks of form in general with reference to these 
four great types as a sort of mould, as it were, in which the different types 
would seem to have been cast. Again, form is alluded to in characterizing orders; 
for instance, in the distinction between the Brachyourans and the Macrourans among 
Crustacea, or between the Saurians, the Ophidians, and the Chelonians. It is men- 
tioned as a distinguishing feature in many families, ex. gr. the Cetacea, the Bats, 
etc. Some genera are separated from others in the same family on the ground 
of differences of form; and in almost every description of species, especially when 
they are considered isolatedly, the form is described at full length. Is there not, 
in this indiscriminate use of the term of form, a confusion of ideas, a want of 
precision in the estimation of what ought to be called form and what might be 
designated by another name? It seems to me to be the case. In the first place, 
when form is considered as characteristic of Radiata or Articulata, or any other 
of the great types of the animal kingdom, it is evident that it is not a definite 
outline and well-determined figure which is meant, but that here the word form 
is used as synonym for plan. Who, for instance, would describe the tubular body of 
an Holothuria as characterized by a form similar to that of the Euryale, or that of 
an Echinus as identical with that of an Asterias? And who does not see that, as 
far as the form is concerned, Ilolothuriae resemble Worms much more than they 
resemble any other Echinoderm, though, as far as the plan of their structure is 
concerned, they are genuine Radiates, and have nothing to do with the Articu- 
lates ? 
Again, a superficial glance at any and all the classes of the animal kingdom 
is sufficient to show that each contains animals of the most diversified forms. 
What can be more different than Bats and Whales, Herons and Parrots, Frogs and 
Sirens, Eels and Turbots, Butterflies and Bugs, Lobsters and Barnacles, Nautilus 
and Cuttlefishes, Slugs and Conchs, Clams and compound Asidians, Pentacrinus and 
Spatangus, Beroe and Physalia, Actinia and Gorgonia ? And yet they belong respec- 
tively to the same class, as they are coupled here: Bats and Whales together, 
etc. It must be obvious, then, that form cannot be a characteristic element of 
classes, if we would understand any thing definite under that name. 
But form has a definite meaning understood everywhere, when applied to well- 
known animals. We speak, for instance, of the human form; an allusion to the 
form of a horse or that of a bull conveys at once a distinct idea; everybody would 
acknowledge the similarity of form of the horse and ass, and knows how to distin- 
guish them by their form from dogs or cats, or from seals and porpoises. In this 
definite meaning, form corresponds also to what we call figure when speaking of 
men and women, and it is when taken in this sense, that I would now consider 
the value of forms as characteristic of different animals. We have seen that form Chap. II. 
FAMILIES. 
157 
cannot be considered as a character of branches, nor of classes; let us now 
examine, further, whether it is a character of species. A rapid review of some of 
the best known types of the animal kingdom, embracing well-defined genera with 
many species, will at once show that this cannot be the case, for such species do 
not generally show the least difference in their forms. Neither the many species 
of Squirrels, nor the true Mice, nor the Weasels, nor the Bears, nor the Eagles, 
nor the Falcons, nor the Sparrows, nor the Warblers, nor the genuine Woodpeckers, 
nor the true Lizards, nor the Frogs, nor the Toads, nor the Skates, nor the Sharks 
proper, nor the Turbots, nor the Soles, nor the Eels, nor the Mackerels, nor the 
Sculpins, nor the genuine Shrimps, nor the Crawfishes, nor the Hawkmoths, nor 
the Geometers, nor the Dorbugs, nor the Spring-Beetles, nor the Tapeworms, 
nor the Cuttlefishes, nor the Slugs, nor the true Asterias, nor the Sea-Anemones, 
could be distinguished among themselves, one from the other, by their form only. 
There may be differences in the proportions of some of their parts, but the pattern 
of every species belonging to well-defined natural genera is so completely identi- 
cal that it will never afford specific characters. There are genera in our system 
which, as they now stand, might be alluded to as examples contrary to this state- 
ment ; but such genera are still based upon very questionable features, and are 
likely to be found in the end to consist of unnatural associations of heterogeneous 
species: at all events, all recent improvements in Zoology have gone to Emit 
genera gradually more and more in such a manner, that the species belonging to 
each have shown successively less and less difference in form, until they have 
assumed, in that respect, the most homogeneous appearance. Are natural genera 
any more to be distinguished by their form one from the other ? Is there any 
appreciable difference in the general form, - I say purposely general form, because 
a more or less prominent nose, larger or smaller ears, longer or shorter claws, 
etc., do not essentially modify the form, - is there any real difference in the general 
form between the genera of the most natural families? Do, for instance, the 
genera of Ursina, the Bears, the Badger, the Wolverines, the Raccoons, differ in form? 
Do the Phocoidae, the Delphinoidae, the Falconinae, the Turdinae, the Fringillince, 
the Picinm, the Scolopacinae, the Chelonioidm, the Geckonina, the Colubrina, the 
Sparoidse, the Elateridae, the Pyralidoidae, the Echinoidae, etc., differ any more among 
themselves ? Certainly not; though to some extent, there are differences in the 
form of the representatives of one genus when compared to those of another genus; 
but when rightly considered, these differences appear only as modifications of the 
same type of forms. Just as there are more or less elongated ellipses, so do we 
find the figure of the Badgers somewhat more contracted than that of either the 
Bears, or the Raccoons, or the Wolverines, that of the Wolverines somewhat more 
elongated than that of the Raccoons; but the form is here as completely typical 158 
ESSAY ON CLASSIFICATION. 
Part I. 
as it is among the Viverrina, or among the Canina, or ajnong. the Bradypodidas, 
or among the Delphinoidae, etc., etc. We must, therefore, exclude form from the 
characteristics of natural genera, or at least introduce it only as a modification of 
the typical form of natural families. 
Of all the natural groups in the animal kingdom there remain then only families 
and orders, for the distinction of which form can apply as an essential criterion. 
But these two kinds of groups are just those upon which zoologists are least 
agreed, so that it may not be easy to find a division which all naturalists 
wrould agree to take as an example of a natural order. Let us, however, do our 
best to settle the difficulty and suppose, for a moment, that what has been said 
above respecting the orders is well founded, that orders are natural groups charac- 
terized by the degree of complication of their structure, and expressing the respec- 
tive rank of these groups in their class, then we shall find less difficulty in 
pointing out some few groups which could be generally considered as orders. I 
suppose most naturalists would agree, for instance, that among Reptiles the Chelo- 
nians constitute a natural order; that among Fishes, Sharks and Skates constitute 
an order also; and if any one wrould urge the necessity of associating also the 
Cyclostomes with them, it would only the better serve my purposes. Ganoids, even 
circumscribed within narrower limits than those I had assigned to them, and 
perhaps reduced to the extreme limits proposed for them by J. Muller, I am 
equally prepared to take as an example, though I have in reality still some objec- 
tions to this limitation, which, however, do not interfere with my present object. 
Decapods, among Crustacea, I suppose everybody would also admit as an order, 
and I do not care here wdiat other families are claimed besides Decapods to com- 
plete the highest order of Crustacea. Among Acephala, I trust Bryozoa, Tunicata, 
Brachiopods, and Lamellibranchiata would be also very generally considered to be 
natural orders. Among Echinoderms, I suppose Crinoids, Asterioids, Echinoids, and 
Ilolothurioids would be conceded also as such natural orders; among Acalephs the 
Beroids, and perhaps also Discophorse and Hydroids; while among the Polypi, the 
Halcyonoids constitute a very natural order when compared with the Actinoids. 
Let us now consider these orders with reference to the characteristic forms they 
include. The forms of the genuine Testudo, of Trionyx, and of Chelonia are very 
different, one from the other, and yet few orders are so wrell circumscribed as that 
of Chelonians. The whole class of Fishes scarcely exhibits greater differences than 
those observed in the forms of the common Sharks, the Sawfishes, the common 
Skates, and the Torpedo, not to speak of the Cyclostomes and Myxinoids, if these 
families were also considered as members of the order of Placoids. Ganoids cannot 
be circumscribed within narrower limits than those assigned to them by J. Muller, 
and yet this order, thus limited, contains forms as heterogeneous as the Sturgeons, Chap. II. 
FAMILIES. 
159 
the Lepidosteus, the Polypterus, the Amia, and a host of extinct genera and families, 
not to speak of those families I had associated with them and which Prof. Muller 
would have removed, which, if included among Ganoids, wrould add still more 
heteromorphous elements to this order. Among Decapods, we need only remember 
the Lobsters and Crabs to be convinced that it is not similarity of form which 
holds them so closely together as a natural order. How heterogeneous Bryozoa, 
Brachiopods, and Tunicata are among themselves, as far as their form is concerned, 
everybody knows who has paid the least attention to these animals. 
Unless, then, form be too vague an element to characterize any kind of natural 
groups in the animal kingdom, it must constitute a prominent feature of families. 
I have already remarked, that orders and families are the groups upon which 
zoologists are least agreed, and to the study and characterizing of which they have 
paid least attention. Does this not arise simply from the fact, that, on the one 
hand, the difference between ordinal and class characters has not been understood, 
and only assumed to be a difference of degree; and, on the other hand, that the 
importance of the form, as the prominent character of families, has been entirely 
overlooked ? For, though so few natural families of animals are well characterized, 
or characterized at all, we cannot open a modern treatise upon any class of 
animals without finding the genera more or less naturally grouped together, under 
the heading of a generic name with a termination in idee or ince indicating family 
and sub-family distinctions; and most of these groups, however unequal in absolute 
value, are really natural groups, though far from designating always natural families, 
being as often orders or sub-orders, as families or sub-families. Yet they indicate 
the facility there is, almost without study, to point out the intermediate natural 
groups between the classes and the genera. This arises, in my opinion, from the 
fact, that family resemblance in the animal kingdom is most strikingly expressed 
in the general form, and that form is an element which falls most easily under 
our perception, even when the observation is made superficially. But, at the same 
time, form is most difficult to describe accurately, and hence the imperfection of 
most of our family characteristics, and the constant substitution for such characters 
of features which are not essential to the family. To prove the correctness of 
this view, I would only appeal to the experience of every naturalist. When we 
see new animals, does not the first glance, that is, the first impression made upon 
us by their form, give us at once a very correct idea of their nearest relation- 
ship ? We perceive, before examining any structural character, whether a Beetle 
is a Carabicine, a Longicorn, an Elaterid, a Curculionid, a Chrysomeline; whether 
a Moth is a Noctuelite, a Geometrid, a Pyralid, etc.; whether a bird is a Dove, 
a Swallow, a Humming-bird, a Woodpecker, a Snipe, a Heron, etc., etc. But before 
we can ascertain its genus, we have to study the structure of some characteristic 160 
ESSAY ON CLASSIFICATION. 
Part I. 
parts; before we can combine families into natural groups, we have to make a 
thorough investigation of their whole structure, and compare it with that of other 
families. So form is characteristic of families; and I can add, from a careful investi- 
gation of the subject for several years past, during which I have reviewed the whole 
animal kingdom with reference to this and other topics connected with classifica- 
tion, that form is the essential characteristic of families.1 I do not mean the mere 
outline, but form as determined by structure; that is to say, that families cannot 
be well defined, nor circumscribed within their natural limits, without a thorough 
investigation of all those features of the internal structure which combine to deter- 
mine the form. 
The characteristic of the North American Chelonians which follows, may serve 
as an example how this subject is to be treated. I will only add here, that how- 
ever easy it is at first, from the general impression made upon us by the form 
of animals, to obtain a glimpse of what may fairly be called families, few inves- 
tigations require more patient comparisons than those by which we ascertain 
the natural range of modifications of any typical form, and the structural features 
upon which it is based. Comparative anatomy has so completely discarded every 
thing that relates to Morphology; the investigations of anatomists lean so uniformly 
towards a general appreciation of the connections and homologies of the organic 
systems which go to build up the body of animals, that for the purpose of under- 
standing the value of forms and their time foundation, they hardly ever afford any 
information, unless it be here and there a consideration respecting teleological rela- 
tions. 
Taking for granted, that orders are natural groups characterized by the com- 
plication of their structure, and that the different orders of a class express the 
different degrees of that complication; taking now further for granted, that families 
are natural groups characterized by their form as determined by structural pecu- 
liarities, it follows that orders are the superior kind of division, as we have seen 
that the several natural divisions which are generally considered as orders, contain 
each several natural groups, characterized by different forms, that is to say, con- 
stituting as many distinct families. 
After this discussion it is hardly necessary to add, that families cannot by any 
means be considered as modifications of the orders to which they belong, if orders 
are to be characterized by the degrees of complication of their structure, and families 
1 These investigations, which have led to most 
interesting results, have delayed thus far the publi- 
cation of the systematic part of the Principles of 
Zoology, undertaken in common with my friend, 
Dr. A. A. Gould, and which I would not allow to 
appear before I could revise the whole animal king- 
dom in this new light, in order to introduce as much 
precision as possible in its classification. Chap. II. 
GENERA. 
161 
by their forms. I would also further remark, that there is one question relating 
to the form of animals, which I have not touched here, and which it is still more 
important to consider in the study of plants, namely, the mode of association of 
individuals into larger or smaller communities, as we observe them, particularly 
among Polyps and Acalephs. These aggregations have not, as far as their form 
is concerned, the same importance as the form of the individual animals of which 
they are composed, and therefore seldom afford trustworthy family characters. But 
this point may be more appropriately considered in connection with the special 
illustration of our Hydroids, to which my next volume is to be devoted. 
I have stated above, that botanists have defined the natural families of plants 
with greater precision than zoologists those of animals; I have further remarked 
also, that most of them make no distinction between orders and families. This 
may be the result of the peculiar character of the vegetable kingdom, which is 
not built upon such entirely different plans of structure as are animals of different 
branches. On the contrary, it is possible to trace among plants a certain gradation 
between their higher and lower types more distinctly than among animals, even 
though they do not, any more than animals, constitute a simple series. It seems 
to me, nevertheless, that if Cryptogams, Gymnosperms, Monocotyledons, and Dico- 
tyledons can be considered as branches of the vegetable kingdom, analogous to 
Radiata, Mollusks, Articulata, and Vertebrata among animals, such divisions as Fungi, 
Algae, Lichens, Mosses, Hepaticae, and Ferns in the widest sense, may be taken as 
classes. Diatomaceae, Confervae, and Fuci may then be considered as orders; Mosses 
and Hepaticae as orders; Equisetaceae, Ferns proper, Hydropterids, and Lycopodiaceae 
as orders also; as they exhibit different degrees of complication of structure, while 
their natural subdivisions, which are more closely allied in form or habitus, may 
be considered as families; natural families among plants having generally as distinct 
a port, as families among animals have a distinct form. We need only remember 
the Palms, the Coniferae, the Umbelliferm, the Composite, the Leguminosae, the Lab- 
iatae, etc., as satisfactory examples of this kind. 
SECTION V. 
GENERA. 
Linnaeus already knew very well that genera exist in nature, though what he 
calls genera constitute frequently groups to which we give at present other names, 
as we consider many of them as families; but it stands proved by his writings 162 
ESSAY ON CLASSIFICATION. 
Part I. 
that lie had fully satisfied himself of the real existence of such groups, for he 
says distinctly in his Phitosophia Botanica, sect. 169, "Scias characterem non con- 
stituere genus, sed genus characterem. Characterem fluere e genere, non genus 
e charactere. Characterem non esse, ut genus fiat, sed ut genus noscatur." 
It is surprising that notwithstanding such clear statements, which might have 
kept naturalists awake respecting the natural foundation of genera, such loose ideas 
have become prevalent upon this subject, that at present the number of inves- 
tigators who exhibit much confidence in the real existence of their own generic 
distinctions is very limited. And as to what genera really are, the want of pre- 
cision of ideas appears still greater. Those who have considered the subject at 
all seem to have come to the conclusion that genera are nothing but groups 
including a certain number of species agreeing in some more general features 
than those which distinguish species; thus recognizing no difference between generic 
and specific characters as such, as a single species may constitute a genus, when- 
ever its characters do not agree with the characters of other species, and many 
species may constitute a genus, because their specific characters agree to a certain 
extent among themselves.1 Far from admitting such doctrines, 1 hope to be able 
to show that, however much or however little species may differ among themselves 
as species, yet they may constitute a natural genus, provided their respective generic 
characters are identical. 
I have stated before, that in order to ascertain upon what the different groups 
adopted in our systems are founded, I consulted the works of such writers as are 
celebrated in the annals of science for having characterized with particular felicity 
any one kind of these groups, and I have mentioned Latreille as prominent among 
zoologists for the precision with which he has defined the genera of Crustacea 
and Insects, upon which he has written the most extensive work extant.2 An 
anecdote which I have often heard repeated by entomologists who knew Latreille 
well, is very characteristic as to the meaning he connected with the idea of genera. 
At the time he was preparing the work just mentioned, he lost no opportunity 
of obtaining specimens, the better to ascertain from nature the generic peculiarities 
of these animals, and he used to apply to the entomologists for contributions to his 
collection. It was not show specimens he cared to obtain, any would do, for he 
used to say he wanted them only "to examine their parts." Have we not here 
a hint, from a master, to teach us what genera are and how they should be 
characterized? Is it not the special structure of some part or other, which charac- 
1 Spring, Ueber die naturhistorischen Begriffe 
von Gattung, Art und Abart, Leipzig, 1838, 1 vol. 
2 Latreille, Genera Crustaceorum und Insect- 
orum, Paris et Argent. 1806-1809, 4 vols. 8vo. Chap. II. 
SPECIES. 
163 
terizes genera ? Is it not the finish of the organization of the body, as worked 
out in the ultimate details of structure, which distinguishes one genus from another? 
Latreille, in expressing the want he felt with reference to the study of genera, 
has given us the key-note of their harmonious relations to one another. Genera 
are most closely allied groups of animals, differing neither in form, nor in com- 
plication of structure, but simply in the ultimate structural peculiarities of some 
of their parts; and this is, I believe, the best definition which can be given of 
genera. They are not characterized by modifications of the features of the fami- 
lies, for we have seen that the prominent trait of family difference is to be found 
in a typical form; and genera of the same family may not differ at all in form. Nor 
are genera merely a more comprehensive mould than the species, embracing a wide 
range of characteristics; for species in a natural genus should not present any 
structural differences, but only such as express the most special relations of their 
representatives to the surrounding world and to each other. Genera, in one word, 
are natural groups of a peculiar kind, and their special distinction rests upon the 
ultimate details of their structure. 
SECTION VI. 
SPECIES. 
It is generally believed that nothing is easier than to determine species, and 
that of all the degrees of relationship which animals exhibit, that which consti- 
tutes specific identity is the most clearly defined. An unfailing criterion of specific 
identity is even supposed to exist in the sexual connection which so naturally 
brings together the individuals of the same species in the function of reproduc- 
tion. But I hold that this is a complete fallacy, or at least a petitio principii, not 
admissible in a philosophical discussion of wThat truly constitutes the characteristics 
of species. I am even satisfied that some of the most perplexing problems involved 
in the consideration of the natural limits of species would have been solved long 
ago, had it not been so generally urged that the ability and natural disposition 
of individuals to connect themselves in fertile sexual intercourse was of itself 
sufficient evidence of their specific identity. Without alluding to the fact that every 
new case of hybridity1 is an ever-returning protest against such an assertion, and 
1 Wiegman, Gekrbnte Preisschrift uber die Bas- 
tarderzeugung im Pflanzenreich, Braunschweig, 1828, 
8vo. - Braun, (A.,) Ueber die Erscheinung der Ver- 
jiingung in der Natur, Freiburg, 1849, 4to. - Mor- 
ton, (S. G.,) Essay on Hybridity, Amer. Jour., 
1847. - Additional Observations on Hybridity in 
Animals and on some collateral subjects, Charleston 
Med. Journ., 1850. 164 
ESSAY ON CLASSIFICATION. 
Part I. 
without entering here into a discussion respecting the possibility or practicability 
of setting aside this difficulty by introducing the consideration of the limited fer- 
tility of the progeny of individuals of different species, 1 will only remark, 
that as long as it is not proved that all the varieties of dogs, and of any others 
of our domesticated animals, and of our cultivated plants, are respectively derived 
from one unmixed species, and as long as doubts can be entertained respecting 
the common origin of all races of men from one common stock, it is not logical 
to admit that sexual connection resulting even in fertile offspring is a trustworthy 
evidence of specific identity. 
To justify this assertion, I would only ask, where is the unprejudiced naturalist 
who in our days would dare to maintain: 1st, that it is proved that all the 
domesticated varieties of sheep, of goats, of bulls, of llamas, of horses, of dogs, 
of fowls, etc., are respectively derived from one common stock; 2d, that the 
supposition that these varieties have originated from the complete amalgamation of 
several primitively distinct species is out of the question; and 3d, that varieties 
imported from distant countries and not before brought together, such as the 
Shanghae fowl, for instance, do not completely mingle 2 Where is the physiologist 
who can conscientiously affirm that the limits of the fertility between distinct 
species are ascertained with sufficient accuracy to make it a test of specific identity? 
And who can say that the distinctive characters of fertile hybrids and of unmixed 
breeds are sufficiently obvious to enable anybody to point out the primitive feat- 
ures of all our domesticated animals, or of all our cultivated plants ? As long 
as this cannot be done, as long as the common origin of all races of men, and 
of the different animals and plants mentioned above, is not proved, while their 
fertility with one another is a fact which has been daily demonstrated for thou- 
sands of years, as long as large numbers of animals are hermaphrodites, never 
requiring a connection with other individuals to multiply their species, as long as 
there are others which multiply in various ways without sexual intercourse, it is 
not justifiable to assume that those animals and plants are unmixed species, and 
that sexual fecundity is the criterion of specific identity. Moreover, this test can 
hardly ever have any practical value in most cases of the highest scientific inter- 
est. It is never resorted to, and, as far as I know, has never been applied with 
satisfactory results to settle any doubtful case. It has never assisted any anxious 
and conscientious naturalist in investigating the degree of relationship between 
closely allied animals or plants living in distant regions or in disconnected geo- 
graphical areas. It will never contribute to the solution of any of those difficult 
cases of seeming difference or identity between extinct animals and plants found 
in different geological formations. In all critical cases, requiring the most minute 
accuracy and precision, it is discarded as unsafe, and of necessity questionable. 
Accurate science must do without it, and the sooner it is altogether discarded, the Chap. II. 
SPECIES. 
165 
better. But, like many relics of past time, it is dragged in as a sort of theo- 
retical bugbear, and exhibited only now and then to make a false show in discus- 
sions upon the question of the unity of origin of mankind. 
There is another fallacy connected with the prevailing ideas about species to 
which I would also allude: the fancy that species do not exist in the same way 
in nature as genera, families, orders, classes, and types. It is actually maintained 
by some that species are founded in nature in a manner different from these groups; 
that their existence is, as it were, more real, whilst that of the other groups is 
considered as ideal, even when it is admitted that these groups have themselves a 
natural foundation. 
Let us consider this point more closely, as it involves the whole question of 
individuality. I wish, however, not to be understood as undervaluing the impor- 
tance of sexual relations as indicative of the close ties which unite, or may unite, 
the individuals of the same species. I know as well as any one to what extent 
they manifest themselves in nature, but I mean to insist upon the undeniable fact 
that these relations are not so exclusive as those naturalists would represent them, 
who urge them as an unfailing criterion of specific identity. I would remind those 
who constantly forget it, that there are animals which, though specifically distinct 
do unite sexually, which do produce offspring, mostly sterile, it is true, in some 
species, but fertile to a limited extent in others, and in others even fertile to an 
extent which it has not yet been possible to determine. Sexual connection is the 
result, or rather one of the most striking expressions of the close relationship 
established in the beginning between individuals of the same species, and by no 
means the cause of their identity in successive generations. When first created, 
animals of the same species paired because they were made one for the other; 
they did not take one another in order to build up their species, which had full 
existence before the first individual produced by sexual connection was born. 
This view of the subject acquires greater importance in proportion as it becomes 
more apparent that species did not originate in single pairs, but were created in 
large numbers, in those numeric proportions which constitute the natural harmonies 
between organized beings. It alone explains the possibility of the procreation 
of Hybrids, as founded upon the natural relationship of individuals of closely 
allied species, which may become fertile with one another, the more readily as they 
differ less, structurally. 
To assume that sexual relations determine the species it should further be shown 
that absolute promiscuousness of sexes among individuals of the same species is the 
prevailing characteristic of the animal kingdom, while the fact is, that a large num- 
ber even of animals, not to speak of Man, select their mate for life and rarely 
have any intercourse with others. It is a fact known to every farmer, that differ- 166 
ESSAY ON CLASSIFICATION. 
Part I. 
ent breeds of the same species are less inclined to mingle than individuals of the 
same breed. For my own part, I cannot conceive how moral philosophers, who 
urge the unity of origin of Man as one of the fundamental principles of their 
religion, can at the same time justify the necessity which it involves of a sexual 
intercourse between the nearest blood relations of that assumed first and unique 
human family, when such a connection is revolting even to the savage. Then again, 
there are innumerable species in which vast numbers of individuals are never 
developed sexually, others in which sexual individuals appear only now and then 
at remote intervals, while many intermediate generations are produced without any 
sexual connection, and others still which multiply more extensively by budding 
than by sexual generation. I need not again allude here to the phenomena of 
alternate generation, now so well known among Acalephs and Worms, nor to 
the polymorphism of many other types. Not to acknowledge the significance of 
such facts, would amount to the absurd pretension, that distinctions and definitions, 
introduced in our science during its infancy, are to be taken as standards for 
our appreciation of the phenomena in nature, instead of framing and remodelling 
our standards, according to the laws of nature, as our knowledge extends. It is, 
for instance, a specific character of the Horse and the Ass to be able to con- 
nect sexually with each other, and thus to produce an offspring different from that 
which they bring forth among themselves. It is characteristic of the Mare, as 
the representative of its species, to bring forth a Mule with the Jackass, and of 
the Stallion to procreate Hinnies with the She-ass. It is equally characteristic of 
them to produce still other kinds of halfbreeds with the Zebra, the Daw, etc. And 
yet in face of all these facts, which render sexual reproduction, or at least pro- 
miscuous intercourse among the representatives of the same species, so questionable 
a criterion of specific identity, there are still naturalists who would represent it as 
an unfailing test, only that they may sustain one single position, that all men are 
derived from one single pair. 
These facts, with other facts which go to show more extensively every day the 
great probability of the independent origin of individuals of the same species in 
disconnected geographical areas, force us to remove from the philosophic definition 
of species the idea of a community of origin, and consequently, also, the idea of 
a necessary genealogical connection. The evidence that all animals have originated 
in large numbers is growing so strong, that the idea that every species existed in 
the beginning in single pairs, may be said to be given up almost entirely by 
naturalists. Now if this is the case, sexual derivation does not constitute a neces- 
sary specific character, even though sexual connection be the natural process of 
their reproduction and multiplication. If we are led to admit as the beginning of 
each species, the simultaneous origin of a large number of individuals, if the same Chap. II. 
SPECIES. 
167 
species may originate at the same time in different localities, these first repre- 
sentatives of each species, at least, were not connected by sexual derivation; and as 
this applies equally to any first pair, this fancied test criterion of specific identity 
must at all events be given up, and with it goes also the pretended real exist- 
ence of the species, in contradistinction from the mode of existence of genera, 
families, orders, classes, and types; for what really exists are individuals, not species. 
We may at the utmost consider individuals as representatives of species, but no one 
individual nor any number of individuals represent its species only, without repre- 
senting also at the same time, as we have seen above (Sect. I. to V.), its genus, its 
family, its order, its class, its type. 
Before attempting to prove the whole of this proposition, I will first con- 
sider the characters of the individual animals. Their existence is scarcely limited 
as to time and space within definite and appreciable limits. No one nor all of 
them represent fully, at any particular time, their species; they are always only the 
temporary representatives of the species, inasmuch as each species exists longer in 
nature than any of its individuals. All the individuals of any or of all species 
now existing are only the successors of other individuals which have gone before, 
and the predecessors of the next generations; they do not constitute the species, 
they represent it. The species is an ideal entity, as much as the genus, the family, 
the order, the class, or the type; it continues to exist, while its representatives 
die, generation after generation. But these representatives do not simply repre- 
sent what is specific in the individual, they exhibit and reproduce in the same 
manner, generation after generation, all that is generic in them, all that charac- 
terizes the family, the order, the class, the branch, with the same fulness, the 
same constancy, the same precision. Species then exist in nature in the same 
manner as any other groups, they are quite as ideal in their mode of existence 
as genera, families, etc., or quite as real. But individuals truly exist in a differ- 
ent way; no one of them exhibits at one time all the characteristics of the species, 
even though it be hermaphrodite, neither do any two represent it, even though 
the species be not polymorphous, for individuals have a growth, a youth, a mature 
age, an old age, and are bound to some limited home during their lifetime. 
It is true species are also limited in their existence; but for our purpose, we can 
consider these limits as boundless, inasmuch as we have no means of fixing their 
duration, either for the past geological ages, or for the present period, whilst 
the short cycles of the life of individuals are easily measurable quantities. Now 
as truly as individuals, while they exist, represent their species for the time being, 
and do not constitute them, so truly do these same individuals represent at the 
same time their genus, their family, their order, their class, and their type, the 
characters of which they bear as indelibly as those of the species. 168 
ESSAY ON CLASSIFICATION. 
Part I. 
As representatives of Species, individual animals bear the closest relations to one 
another; they exhibit definite relations also to the surrounding elements, and their 
existence is limited within a definite period. 
As* representatives of Genera, these same individuals have a definite and specific 
ultimate structure, identical with that of the representatives of other species. 
As representatives of Families, these same individuals have a definite figure exhibit- 
ing, with similar forms of other genera, or for themselves, if the family contains 
but one genus, a distinct specific pattern. 
As representatives of Orders, these same individuals stand in a definite rank when 
compared to the representatives of other families. 
As representatives of Classes, these same individuals exhibit the plan of structure 
of their respective type in a special manner, carried out with special means and 
in special ways. 
As representatives of Branches, these same individuals are all organized upon a dis- 
tinct plan, differing from the plan of other types. 
Individuals then are the bearers, for the time being, not only of specific char- 
acteristics, but of all the natural features in which animal life is displayed in all 
its diversity. 
Viewing individuals in this light, they resume all their dignity; they are no 
longer absorbed in the species to be for ever its representatives, without ever being 
any thing for themselves. On the contrary, it becomes plain, from this point of view, 
that the individual is the worthy bearer, for the time being, of all the riches of 
nature's wealth of life. This view further teaches us how we may investigate, not 
only the species in the individual, but the genus also, the family, the order, the 
class, the type, as indeed naturalists have at all times proved in practice, whilst 
denying the possibility of it in theory. 
Having thus cleared the field of what does not belong therein, it now remains 
for me to show what in reality constitutes species, and how they may be dis- 
tinguished with precision within their natural limits. 
If we would not exclude from the characteristics of species any feature which is 
essential to it, nor force into it any one which is not so, we must first acknowledge 
that it is one of the characters of species to belong to a given period in the 
history of our globe, and to hold definite relations to the physical conditions then 
prevailing, and to animals and plants then existing. These relations are manifold, 
and are exhibited: 1st, in the geographical range natural to any species, as well 
as in its capability of being acclimated in countries where it is not primitively 
found; 2d, in the connection in which they stand to the elements around them, 
when they inhabit either the water, or the land, deep seas, brooks, rivers and 
lakes, shoals, flat, sandy, muddy, or rocky coasts, limestone banks, coral reefs, swamps, Chap. II. 
SPECIES. 
169 
meadows, fields, dry lands, salt deserts, sandy deserts, moist land, forests, shady groves, 
sunny hills, low regions, plains, prairies, high table-lands, mountain peaks, or the 
frozen barrens of the Arctics, etc.; 3d, in their dependence upon this or that kind 
of food for their sustenance; 4th, in the duration of their life; 5th, in the mode 
of their association with one another, whether living in flocks, small companies, or 
isolated; 6th, in the period of their reproduction; 7th, in the changes they undergo 
during their growth, and the periodicity of these changes in their metamorphosis; 
8th, in their association with other beings, which is more or less close, as it 
may only lead to a constant association in some, whilst in others it amounts 
to parasitism; 9th, specific characteristics are further exhibited in the size animals 
attain, in the proportions of their parts to one another, in their ornamentation, 
etc., and all the variations to which they are liable. 
As soon as all the facts bearing upon these different points have been fully 
ascertained, there can remain no doubt respecting the natural limitation of species; 
and it is only the insatiable desire of describing new species from insufficient data 
which has led to the introduction in our systems of so many doubtful species, 
which add nothing to our real knowledge, and only go to swell the nomenclature 
of animals and plants already so intricate. 
Assuming then, that species cannot always be identified at first sight, that it 
may require a long time and patient investigations to ascertain their natural limits; 
assuming further, that the features alluded to above are among the most promi- 
nent characteristics of species, we may say, that species are based upon well 
determined relations of individuals to the world around them, to their kindred, and 
upon the proportions and relations of their parts to one another, as well as upon their 
ornamentation. Well digested descriptions of species ought, therefore, to be com- 
parative; they ought to assume the character of biographies, and attempt to trace 
the origin and follow the development of a species during its whole existence. 
Moreover, all the changes which species may undergo in course of time, especially 
under the fostering care of man, in the state of domesticity and cultivation, belong 
to the history of the species; even the anomalies and diseases to which they are 
subject, belong to their cycle, as well as their natural variations. Among some 
species, variation of color is frequent, others never change, some change periodi- 
cally, others accidentally; some throw off certain ornamental appendages at regular 
times, the Deers their horns, some Birds the ornamental plumage they wear in 
the breeding season, etc. All this should be ascertained for each, and no species 
can be considered as well defined and satisfactorily characterized, the whole history 
of which is not completed to the extent alluded to above. The practice prevailing 
since Linnaaus of limiting the characteristics of species to mere diagnoses, has led 
to the present confusion of our nomenclature, and made it often impossible to 170 
ESSAY ON CLASSIFICATION. 
Part I. 
ascertain what were the species the authors of such condensed descriptions had 
before them. But for the tradition which has transmitted, generation after gener- 
ation, the knowledge of these species among the cultivators of science in Europe, 
this confusion would be still greater; but for the preservation of most original 
collections it would be inextricable. In countries, which, like America, do not enjoy 
these advantages, it is often hopeless to attempt critical investigations upon doubtful 
cases of this kind. One of our ablest and most critical investigators, the lamented 
Dr. Harris, has very forcibly set forth the difficulties under which American 
naturalists labor in this respect, in the Preface to his Report upon the Insects 
Injurious to Vegetation. 
SECTION VII. 
OTHER NATURAL DIVISIONS AMONG ANIMALS. 
Thus far I have considered only those kinds of divisions which are introduced 
in almost all our modern classifications, and attempted to show that these groups 
are founded in nature and ought not to be considered as artificial devices, invented 
by man to facilitate his studies. Upon the closest scrutiny of the subject, I find 
that these divisions cover all the categories of relationship which exist among 
animals, as far as their structure is concerned. 
Branches or types are characterized by the plan of their structure, 
Classes, by the manner in which that plan is executed, as far as ways and means 
are concerned, 
Orders, by the degrees of complication of that structure, 
Families, by their form, as far as determined by structure, 
Genera, by the details of the execution in special parts, and 
Species, by the relations of individuals to one another and to the world in 
which they live, as well as by the proportions of their parts, their ornamenta- 
tion, etc. 
And yet there are other natural divisions which must be acknowledged in a 
natural zoological system; but these are not to be traced so uniformly in all 
classes as the former, - they are in reality only limitations of the other kinds of 
divisions. 
A class in which one system of organs may present a peculiar development, 
while all the other systems coincide, may be subdivided into sub-classes; for instance, 
the Marsupialia when contrasted with the Placental Mammalia. The characters Chap. II. 
OTHER NATURAL DIVISIONS. 
171 
upon which such a subdivision is founded, are of the kind upon which the class 
itself is based, but do not extend to the whole class. An order may embrace 
natural groups, of a higher value than families, founded upon ordinal characters, 
which may yet not determine absolute superiority or inferiority, and therefore not 
constitute for themselves distinct orders; as the characters upon which they are 
founded, though of the kind which determines orders, may be so blended as to 
determine superiority in one respect, while with reference to some other features 
they may indicate inferiority. Such groups are called sub-orders. The order of 
Testudinata, which I shall consider more in detail in the second part of this volume, 
may best illustrate this point, as it contains two natural sub-orders. A natural 
family may exhibit such modifications of its characteristic form, that upon these 
modifications subdivisions may be distinguished, which have been called sub-families 
by some authors, tribes or legions by others. In a natural genus, a number of 
species may agree more closely than others in the particulars which constitute 
the genus and lead to the distinction of sub-genera. The individuals of a species, 
occupying distinct fields of its natural geographical area, may differ somewhat from 
one another, and constitute varieties, etc. 
These distinctions have long ago been introduced into our systems, and every 
practical naturalist, who has made a special study of any class of the animal king- 
dom, must have been impressed with the propriety of acknowledging a large number 
of subdivisions, to express all the various degrees of affinity of the different members 
of any higher natural group. Now, while I maintain that the branches, the classes, 
the orders, the families, the genera, and the species are groups established in nature 
respectively upon different categories, and while I feel prepared to trace the natural 
limits of these groups by the characteristic features upon which they are founded, 
I must confess at the same time that I have not yet been able to discover the 
principle which obtains in the limitation of their respective subdivisions. All I 
can say is, that all the different categories considered above, upon which branches, 
classes, orders, families, genera, and species are founded, have their degrees, and upon 
these degrees sub-classes, sub-orders, sub-families, and sub-genera have been established. 
For the present, these subdivisions must be left to arbitrary estimations, and we 
shall have to deal with them as well as we can, as long as the principles which 
regulate these degrees in the different kinds of groups are not ascertained. I 
hope, nevertheless, that such arbitrary estimations are for ever removed from our 
science, as far as the categories themselves are concerned. 
Thus far, inequality of weight seems to be the standard of the internal valua- 
tion of each kind of group; and this inequality extends to all groups, for even 
within the branches there are classes more closely related among themselves 
than others: Polypi and Acalephs, for instance, stand nearer to one another than 172 
ESSAY ON CLASSIFICATION. 
Part I. 
to Echinoderms; Crustacea and Insects are more closely allied to one another than 
to Worms, etc. Upon such degrees of relationship between the classes, within 
their respective branches, the so-called sub-types have been founded, and these differ- 
ences have occasionally been exaggerated so far as to give rise to the establishment 
of distinct branches. Upon similar relations between the branches, sub-kingdoms 
have also been distinguished, but I hardly think that such far-fetched combinations 
can be considered as natural groups; they seem to me rather the expression of 
a relation arising from the weight of their whole organization, as compared with 
that of other groups, than the expression of a definite relationship. 
SECTION VIII. 
SUCCESSIVE DEVELOPMENT OF CHARACTERS. 
It has been repeated, again and again, that the characters distinguishing the 
different types of the animal kingdom were developed in the embryo in the suc- 
cessive order of their importance: first the structural features of their respective 
branches, next the characters of the class, next those of the order, next those 
of the family, next those of the genus, and finally those of the species. This 
assertion has met with no direct opposition; on the contrary, it seems to have been 
approved almost without discussion, and to be generally taken for granted now. 
The importance of the subject requires, however, a closer scrutiny; for if Embry- 
ology is to lead to great improvements in Zoology, it is necessary, at the outset, 
to determine well what kind of information we may expect it to furnish to its 
sister science. Now I would ask if, at this day, zoologists know with sufficient 
precision what are typical, class, ordinal, family, generic, and specific characters, to 
be justified in maintaining that, in the progress of embryonic growth, the features 
which become successively prominent correspond to these characters and in the 
order of their subordination ? I doubt it. I will say more: I am sure there is 
no such understanding about it among them, for if there was, they would already 
have perceived that this assumed coincidence, between the subordination of natural 
groups among full-grown animals and the successive stages of growth during their 
embryonic period of life, does not exist in nature. It is true, there are certain 
features in the embryonic development which may suggest the idea of a progress 
from a more general typical organization to its ultimate specialization, but it nowhere 
proceeds in that stereotyped order of succession, nor indeed even in a general way, 
in the manner thus assumed. Chap. II. 
SUCCESSION OF CHARACTERS. 
173 
Let us see whether it is not possible to introduce more precision in this matter. 
Taking for granted that what I have said about the characteristics of the natural 
groups in the animal kingdom is correct, that we have, 1st, four great typical 
branches of the animal kingdom, characterized by different plans of structure; 
2d, classes, characterized by the ways in which and the means with which these 
plans of structure are executed; 3d, orders, characterized by the degrees of simplicity 
or complication of that structure; 4th, families, characterized by differences of form, 
or by the structural peculiarities determining form; 5th, genera, characterized by 
ultimate peculiarities of structure in the parts of the body; Gth, species, charac- 
terized by relations and proportions of parts among themselves, and of the indi- 
viduals to one another and to the surrounding mediums; we reach, finally, the 
individuals, which, for the time being, represent not only the species with all 
their varieties, and variations of age, sex, size, etc., but also the characteristic features 
of all the higher groups. We have thus, at one end of the series, the most com- 
prehensive categories of the structure of animals, while at the other end we meet 
individual beings. Individuality on one side, the most extensive divisions of the 
animal kingdom on the other. Now, to begin our critical examination of the 
progress of life in its successive manifestations with the extremes, is it not plain, 
from all we know of Embryology, that individualization is the first requirement 
of all reproduction and multiplication, and that an individual germ, (or a number 
of them,) an ovarian egg, or a bud, is first formed and becomes distinct as an 
individual from the body of the parent, before it assumes either the characters 
of its great type or those of its class, order, etc. ? This fact is of great significance, 
as showing the importance of individuality in nature. Next, it is true, we perceive 
generally the outlines of the plan of structure, before it becomes apparent in 
what manner that plan is to be carried out; the character of the type is marked 
out, in its most general features, before that of the class can be recognized with 
any degree of precision. Upon this fact, we may base one of the most important 
generalizations in Embryology. 
It has been maintained, in the most general terms, that the higher animals 
pass during their development through all the phases characteristic of the inferior 
classes. Put in this form, no statement can be further from the truth, and yet 
there are decided relations within certain limits, between the embryonic stages of 
growth of higher animals and the permanent characters of others of an inferior 
grade. Now the fact mentioned above, enables us to mark with precision the limits 
within which these relations may be traced. As eggs, in their primitive condi- 
tion, animals do not differ one from the other; but as soon as the embryo has 
begun to show any characteristic features, it presents such peculiarities as dis- 
tinguish its type. It cannot, therefore, be said that any animal passes through 174 
ESSAY ON CLASSIFICATION. 
Part I. 
phases of development, which are not included within the limits of its own type; 
no Vertebrate is, or resembles, at any time an Articulate, no Articulate a Mollusk, 
no Mollusk a Radiate, and vice versa. Whatever correlations between the young of 
higher animals and the perfect condition of inferior ones may be traced, they are 
always limited to representatives of the same great types; for instance, Mammalia 
and Birds, in their earlier development, exhibit certain features of the lower classes 
of Vertebrates, such as the Reptiles or Fishes; Insects recall the Worms in some 
of their earlier stages of growth, etc., but even this requires qualifications to 
which we shall have to refer hereafter. However, thus much is already evident, 
that no higher animal passes through phases of development recalling all the lower 
types of the animal kingdom, but only such as belong to its own branch. What 
has been said of the infusorial character of young embryos of Worms, Mollusks, 
and Radiates, can no longer stand before a serious criticism, because, in the first 
place, the animals generally called Infusoria cannot themselves be considered as a 
natural class; and in the second place, those to which a reference is made in this 
connection, are themselves free-moving embryos.1 
With the progress of growth and in proportion as the type of an animal 
becomes more distinctly marked, in its embryonic state, the plan of structure appears 
also more distinctly in the peculiarities of that structure, that is to say, in the 
ways in which and the means by which the plan, only faintly indicated at first, 
is to be carried out and become prominent, and by this the class character is 
pointed out. For instance, a wormlike insect larva will already show, by its tracheae, 
that it is to be an Insect and not to remain a Worm, as it at first appears to 
be; but the complications of that special structure, upon which the orders of 
the class of Insects are based, do not yet appear; this is perfected only at a late 
period in the embryonic life. At this stage, we frequently notice already a remark- 
able advance of the features characteristic of the families over those characteristic of 
the order; for instance, young Hemiptera, young Orthoptera may safely be referred 
to their respective families, from the characteristics they exhibit before they show 
those peculiarities which characterize them as Hemiptera or as Orthoptera; young 
Fishes may be known as members of their respective families before the charac- 
ters of their orders are apparent, etc. 
It is very obvious why this should be so. With the progress of the develop- 
ment of the structure, the general form is gradually sketched out, and it has 
already reached many of its most distinctive features, before all the complications 
of the structure which characterize the orders have become apparent; and as form 
characterizes essentially the families, we see here the reason why the family type 
1 See above, Chap. I., Sect. 18, p. 75. Chap. II. 
SUCCESSION OF CHARACTERS. 
175 
may be fully stamped upon an animal before its ordinal characters are developed. 
Even specific characters, as far as they depend upon the proportions of parts and 
have on that ground an influence in modifying the form, may be recognized long 
before the ordinal characters are fully developed. The Snapping-Turtle, for instance, 
exhibits its small crosslike sternum, its long tail, its ferocious habits even before it 
leaves the egg, before it breathes through lungs, before its derm is ossified to form 
a bony shield, etc.; nay, it snaps with its gaping jaws at any thing brought 
near, though it be still surrounded by its amnios and allantois, and its yolk still 
exceeds in bulk its whole body.1 The calf assumes the form of the bull before 
it bears the characteristics of the hollow-horned Ruminants; the fawn exhibits all 
the peculiarities of its species before those of its family are unfolded. 
With reference to generic characters, it may be said that they are scarcely 
ever developed in any type of the animal kingdom, before the specific features 
are for the most part fully sketched out, if not completely developed. Can there 
be any doubt that the human embryo belongs to the genus Homo, even before it 
has cut a tooth? Is not a kitten, or a puppy distinguishable as a cat or a dog, 
before the claws and teeth tell their genus? Is this not true also of the Lamb, 
the Kid, the Colt, the Rabbits, and the Mice, of most Birds, most Reptiles, most 
Fishes, most Insects, Mollusks and Radiates? And wThy should this be? Simply, 
because the proportions of parts, which constitute specific characters, are recog- 
nizable before their ultimate structural development, which characterizes genera, is 
completed. 
It seems to me that these facts are likely to influence the future progress 
of Zoology, in enabling us gradually to unravel more and more distinctly, the 
features which characterize the different subordinate groups of the animal king- 
dom. The views I have expressed above of the respective value and the promi- 
nent characteristics of these different groups, have stood so completely the test in 
this analysis of their successive appearance, that I consider this circumstance as 
adding to the probability of their correctness. 
But this has another very important bearing, to which I have already alluded 
in the beginning of these remarks. Before Embryology can furnish the means of 
settling some of the most perplexing problems in Zoology, it is indispensable to 
ascertain first what are typical, classic, ordinal, family, generic, and specific charac- 
ters; and as long as it could be supposed that these characters appear necessarily 
1 Pr. M. v. Neu-Wied quotes as a remarkable 
fact, that the Chelonara serpentina bites as soon as it 
is hatched. I have seen it snapping in the same 
fierce manner as it does when full-grown, at a time 
it was still a pale, almost colorless embryo, wrapped 
up in its foetal envelopes, with a yolk larger than 
itself hanging from its sternum, three months before 
hatching. 176 
ESSAY ON CLASSIFICATION. 
Part I. 
during the embryonic growth, in the order of their subordination, there was no 
possibility of deriving from embryological monographs, that information upon this 
point, so much needed in Zoology, and so seldom alluded to by embryologists. 
Again, without knowing what constitutes truly the characters of the groups named 
above, there is no possibility of finding out the true characters of a genus of 
which only one species is known, of a family which contains only one genus, etc., 
and for the same reason no possibility of arriving at congruent results with refer- 
ence to the natural limitations of genera, families, orders, etc., without which we 
cannot even begin to build up a permanent classification of the animal kingdom; 
and still less, hope to establish a solid basis for a general comparison between 
the animals now living and those which have peopled the surface of our globe 
in past geological ages. 
It is not accidentally I have been led to these investigations, but by necessity. 
As often as I tried to compare higher or more limited groups of animals of the 
present period with those of former ages, or early stages of growth of higher living 
animals with full-grown ones of lower types, I was constantly stopped in my 
progress by doubts as to the equality of the standards I was applying, until I 
made the standards themselves the object of direct and very extensive investiga- 
tions, covering indeed a much wider ground than would appear from these remarks, 
for, upon these principles, I have already remodelled, for my own convenience, nearly 
the whole animal kingdom, and introduced in almost every class very unexpected 
changes in the classification. 
I have already expressed above1 my conviction that the only true system is 
that which exists in nature, and as, therefore, no one should have the ambition 
of erecting a system of his own, I will not even attempt now to present these 
results in the shape of a diagram, but remain satisfied to express my belief, that 
all we can really do is, at best, to offer imperfect translations in human language 
of the profound thoughts, the innumerable relations, the unfathomable meaning of 
the plan actually manifested in the natural objects themselves; and I should con- 
sider it as my highest reward should I find, after a number of years, that I had 
helped others on in the right path. 
1 See Chap. I., Sect. 1, p. 7-9 Chap. II. 
CONCLUSIONS. 
177 
SECTION IX. 
CONCLUSIONS. 
The importance of such an investigation as the preceding, must be obvious to 
every philosophical investigator. As soon as it is understood that all the different 
groups introduced into a natural system may have a definite meaning; as soon 
as it can be shown that each exhibits a definite relation among living beings, 
founded in nature, and no more subject to arbitrary modifications than any other 
law expressing natural phenomena; as soon as it is made plain that the natural 
limits of all these groups may be ascertained by careful investigations, the interest 
in the study of classification or the systematic relationship existing among all 
organized beings, which has almost ceased to engage the attention of the more 
careful original investigators, will be revived, and the manifold ties which link 
together all animals and plants, as the living expression of a gigantic conception, 
carried out in the course of time, like a soul-breathing epos, will be scrutinized 
anew, determined with greater precision, and expressed with increasing clearness 
and propriety. Fanciful and artificial classifications will gradually lose their hold 
upon a better informed community; scientific men themselves will be restrained 
from bringing forward immature and premature investigations; no characteristics of 
new species will have a claim upon the notice of the learned, which has not been 
fully investigated and compared with those most closely allied to it; no genus 
will be admitted, the structural peculiarities of which are not clearly and distinctly 
illustrated; no family will be considered as well founded, which shall not exhibit 
a distinct system of forms intimately combined and determined by structural rela- 
tions ; no order will appear admissible, which shall not represent a well-marked 
degree of structural complication; no class will deserve that name, which shall 
not appear as a distinct and independent expression of some general plan of struc- 
ture, carried out in a peculiar way and with peculiar means; no type will be 
recognized as one of the fundamental groups of the animal kingdom, which shall 
not exhibit a plan of its own, not convertible into another. No naturalist will 
be justified in introducing any one of these groups into our systems without show- 
ing : 1st, that it is a natural group; 2d, that it is a group of this or that kind, 
to avoid, henceforth, calling families groups that may be genera, families groups that 
may be orders, classes or types groups that may be orders or classes; 3d, that the 
characters by which these groups may be recognized are in fact respectively specific, 178 
ESSAY ON CLASSIFICATION. 
Part I. 
generic, family, ordinal, classic, or typical characters, so that our works shall no 
longer exhibit the annoying confusion, which is to be met almost everywhere, of 
generic characters in the diagnoses of species, or of family and ordinal characters 
in the characteristics of classes and types.1 
It may perhaps be said, that all this will not render the study of Zoology 
more easy. I do not expect that it will; but if an attentive consideration of what 
I have stated in the preceding pages respecting classification, should lead to a 
more accurate investigation of all the different relations existing among animals, 
and between them and the world in which they live, I shall consider myself 
as having fully succeeded in the object I have had in view from the beginning, 
in this inquiry. Moreover, it is high time that certain zoologists, who would call 
themselves investigators, should remember, that natural objects, to be fully under- 
stood, require more than a passing glance; they should imitate the example of 
astronomers, who have not become tired of looking into the relations of the few 
members of our solar system to determine, with increased precision, their motions, 
their size, their physical constitution, and keep in mind that every organized 
being, however simple in its structure, presents to our appreciation far more com- 
plicated phenomena, within our reach, than all the celestial bodies put together; 
they should remember, that as the great literary productions of past ages attract 
ever anew the attention of scholars, who can never feel that they have exhausted 
the inquiry into their depth and beauty, so the living works of God, which it is 
the proper sphere of Zoology to study, would never cease to present new attractions 
to them, should they proceed to the investigation with the right spirit. Their 
studies ought, indeed, inspire every one with due reverence and admiration for such 
wonderful productions. 
The subject of classification in particular, which seems to embrace apparently 
so limited a field in the science of animals, cannot be rightly and fully under- 
stood without a comprehensive knowledge of all the topics alluded to in the 
preceding pages. 
1 As I do not wish to be personal, I will refrain 
from quoting examples to justify this assertion. I 
would only request those who care to be accurate, to 
examine critically almost any description of species, 
any characterization of genera, of families, of orders, 
of classes, and of types, to satisfy themselves that 
characters of the same kind are introduced almost 
indiscriminately to distinguish all these groups. CHAPTER THIRD. 
NOTICE OF THE PRINCIPAL SYSTEMS OF ZOOLOGY. 
SECTION I. 
GENERAL REMARKS UPON MODERN SYSTEMS. 
Without attempting to give an historical account of the leading features of all 
zoological systems, it is proper that I should here compare critically the practice 
of modern naturalists with the principles discussed above. With this view, it 
would hardly be necessary to go back beyond the publication of the " Animal 
Kingdom," by Cuvier, were it not that Cuvier is still represented, by many naturalists, 
and especially by Ehrenberg,1 and some other German zoologists, as favoring the 
division of the whole animal kingdom into two great groups, one containing the 
Vertebrates, and the other all the remaining classes, under the name of Inverte- 
brates, while in reality it was he, who first, dismissing his own earlier views, 
introduced into the classification of the animal kingdom that fourfold division which 
has been the basis of all improvements in modern Zoology. He first showed that 
animals differ, not only by modifications of one and the same organic structure, 
but are constructed upon four different plans of structure, forming natural, distinct 
groups, which he called Radiata, Articulata, Mollusca, and Vertebrata. 
It is true, that the further subdivisions of these leading groups have under- 
gone many changes since the publication of the "Regne Animal." Many smaller 
groups, even entire classes, have been removed from one of his " embranchments " 
to another; but it is equally true, that the characteristic idea which lies at the 
bottom of these great divisions was first recognized by him, the greatest zoologist 
of all times. 
1 Ehrenberg, (C. G.,) Die Corallenthiere des rothen Meeres, Berlin, 1834, 4to., p. 30. 180 
ESSAY ON CLASSIFICATION. 
Part I. 
The question which I would examine here in particular, is not whether the 
circumscription of these great groups was accurately defined by Cuvier, whether 
the minor groups referred to them truly belong there or elsewhere, nor how far 
these divisions may be improved within their respective limits, but whether there 
are four great fundamental groups in the animal kingdom, based upon four differ- 
ent plans of structure, and neither more nor less than four. This question is 
very seasonable, since modern zoologists, and especially Siebold, Leuckart, and Vogt 
have proposed combinations of the classes of the animal kingdom into higher groups, 
differing essentially from those of Cuvier. It is but justice to Leuckart to say 
that he has exhibited, in the discussion of this subject, an acquaintance with the 
whole range of Invertebrata,1 which demands a careful consideration of the changes 
he proposes, as they are based upon a critical discrimination of differences of great 
value, though I think he overrates their importance. The modifications intro- 
duced by Vogt, on the contrary, appear to me to be based upon entirely unphysio- 
logical principles, though seemingly borrowed from that all important guide, Em- 
bryology. 
The divisions adopted by Leuckart are: Protozoa, (though he does not enter 
upon an elaborate consideration of that group,) Coelenterata, Echinodermata, Vermes, 
Arthropoda, Mollusca, and Vertebrata. The classification adopted, many years before, 
by Siebold, in his text-book of comparative anatomy, is nearly the same, except 
that Mollusks follow the Worms, that Coelenterata and Echinoderms are united 
into one group, and that the Bryozoa are left among the Polyps. 
Here we have a real improvement upon the classification of Cuvier, inasmuch 
as the Worms are removed from among the Radiates, and brought nearer the 
Arthropods, an improvement however, which, so far as it is correct, has already 
been anticipated by many naturalists, since Blainville and other zoologists long 
ago felt the impropriety of allowing them to remain among Radiates, and have 
been induced to associate them more or less closely with Articulates. But I 
believe the union of Bryozoa and Rotifera with the Worms, proposed by Leuckart, 
to be a great mistake; as to the separation of Coelenterata from Echinoderms, I 
consider it as an exaggeration of the difference which exists between Polyps and 
Acalephs on the one hand, and Echinoderms on the other. 
The fundamental groups adopted by Vogt,2 are: Protozoa, Radiata, Vermes, Mol- 
lusca, Cephalopoda, Articulata, and Vertebrata, an arrangement which is based solely 
upon the relations of the embryo to the yolk, or the absence of eggs. But, as 
1 Leuckart, (R.,) Ueber die Morphologic und die 
Verwandtshaftsverhaltnisse der wirbellosen Thiere, 
Braunschweig, 1848, 1 vol., 8vo. 
2 Vogt, (Carl,) Zoologische Briefe. Naturge- 
schichte der lebenden und untergegangenen Thiere. 
Frankfurt a. M., 1851; vol. 1, p. 70. Chap. III. 
MODERN SYSTEMS. 
181 
I have already stated, this is an entirely unphysiological principle, inasmuch as it 
assumes a contrast between the yolk and the embryo, within limits which do not 
exist in nature. The Mammalia, for instance, which are placed, like all other Verte- 
brata, in the category of the animals in which there is an opposition between the 
embryo and the yolk, are as much formed of the whole yolk as the Echinoderms 
or Mollusks. The yolk undergoes a complete segmentation in Mammalia, as well as 
in Radiates or Worms, and most Mollusks; and the embryo when it makes its 
appearance no more stands out from the yolk, than the little Starfish stands 
out from its yolk. These simple facts, known since Sars and Bischoff published 
their first observations, twenty years ago, is in itself sufficient to show that the 
whole principle of classification of Vogt is radically wrong. 
Respecting the assertion, that neither Infusoria nor Rhizopoda produce any eggs, 
I shall have more to say presently. As to the arrangement of the leading groups, 
Vertebrata, Articulata, Cephalopoda, Mollusca, Vermes, Radiata, and Protozoa in 
Vogt's system, it must be apparent to every zoologist conversant with the natural 
affinities of animals, that a classification which interposes the whole series of Mollusks 
between the types of Articulata and Worms, cannot be correct. A classification 
based, like this, solely upon the changes which the yolk undergoes, is not likely 
to be the natural expression of the manifold relations existing between all animals. 
Indeed, no system can be true to nature, which is based upon the consideration 
of a single part, or a single organ. 
After these general remarks, I have only to show more in detail, why I believe 
that there are only four great fundamental groups in the animal kingdom, neither 
more nor less. 
With reference to Protozoa, first, it must be acknowledged that, notwithstanding 
the extensive investigation of modern writers upon Infusoria and Rhizopoda, the 
true nature of these beings is still very little known. The Rhizopoda have been 
wandering from one end of the series of Invertebrata to the other, without finding 
a place generally acknowledged as expressing their true affinities. The attempt 
to separate them from all the classes with which they have been so long associated, 
and to place them with the Infusoria in one distinct branch, appears to me as 
mistaken as any of the former arrangements, for I do not even consider that their 
animal nature is yet proved beyond a doubt, though I have myself once sug- 
gested the possibility of a definite relation between them and the lowest Gaste- 
ropods. Since it has been satisfactorily ascertained that the Corallines are genuine 
Algae, which contain more or less lime in their structure, and since there is hardly 
any group among the lower animals and lower plants, which does not contain 
simple locomotive individuals, as well as compound communities, either free or adher- 
ing to the soil, I do not see that the facts known at present preclude the possibility 182 
ESSAY ON CLASSIFICATION. 
Part I. 
of an association of the Rhizopods with the Alga?.1 This would almost seem natural, 
when we consider that the vesicles of many Fuci contain a viscid, filamentous 
substance, so similar to that protruded from the body of the Rhizopods, that the 
most careful microscopic examination does not disclose the slightest difference in its 
structure from that which mainly forms the body of Rhizopods. The discovery 
by Schultze2 of what he considers as the germinal granules of these beings, by no 
means settles this question, though we have similar ovoid masses in Alga?, and 
though, among the latter, locomotive forms are also very numerous. 
With reference to the Infusoria, I have long since expressed my conviction that 
they are an unnatural combination of the most heterogeneous beings. A large 
number of them, the Desmidiea? and Volvocinse, are locomotive Algae. Indeed, 
recent investigations seem to have established beyond all question, the fact, that 
all the Infusoria Anentera of Ehrenberg are Algae. The Enterodela, however, are 
true animals, but belong to two very distinct types, for the Vorticellidae differ 
entirely from all others. Indeed, they are, in my opinion, the only independent 
animals of that group, and so far from having any natural affinity with the other 
Enterodela, I do not doubt that their true place is by the side of Bryozoa, 
among Mollusks, as I shall attempt to show presently. Isolated observations which 
I have been able to make upon Paramecium, Opalina, and the like, seem to me 
sufficient to justify the assumption that they disclose the true nature of the 
bulk of this group. I have seen, for instance, a Planaria lay eggs out of which 
Paramecium were born, which underwent all the changes these animals are known to 
undergo up to the time of their contraction into a chrysalis state; while the Opalina 
is hatched from Distoma eggs. I shall publish the details of these observations 
on another occasion. But if it can be shown that two such types as Paramecium 
and Opalina are the progeny of Worms, it seems to me to follow, that all the 
Enterodela, with the exception of the Vorticellidaa, must be considered as the 
embryonic condition of that host of Worms, both parasitic and free, the meta- 
morphosis of which is still unstudied. In this connection, I might further remark, 
that the time is not long past when Cercaria was also considered as belonging 
to the class of Infusoria, though at present no one doubts that it belongs to 
the cycle of Distoma; and the only link in the metamorphosis of that genus which 
was not known is now supplied, since, as I have stated above, the embryo which 
is hatched from the egg laid by the perfect Distoma is found to be Opalina. 
All this leads to the conclusion, that a division of the animal kingdom to be 
called Protozoa, differing from all other animals in producing no eggs, does not 
exist in nature, and that the beings which have been referred to it have now 
1 Comp. Chap. I., Sect. 18, p. 75. 
2 Schultze, (M. S.,) Polythalamien, q. a.; p. 24. Chap. III. 
MODERN SYSTEMS. 
183 
to be divided, and scattered, partly among plants, in the class of Algae, and partly 
among animals, in the classes of Acephala, (Vorticellae,) of Worms, (Paramecium and 
Opalina,) and of Crustacea (Rotifera); Vorticellae being genuine Bryozoa and there- 
fore Acephalous Mollusks, while the beautiful investigations of Dana and Leydig 
have proved the Rotifera to be genuine Crustacea, and not Worms. 
The great type of Radiata, taking its leading features only, was first recognized 
by Cuvier, though he associated with it many animals which do not properly 
belong to it. This arose partly from the imperfect knowledge of those animals 
at the time, but partly also from the fact that he allowed himself, in this instance, 
to deviate from his own principle of classification, according to which types are 
founded upon special plans of structure. With reference to Radiata, he departed, 
indeed, from this view, so far as to admit, besides the consideration of their peculiar 
plan, the element of simplicity of their structure as an essential feature in the 
typical character of these animals, in consequence of which he introduced five classes 
among Radiata: the Echinoderms, Intestinal Worms, Acalephs, Polypi, and Infusoria. 
In opposition to this unnatural association, I need not repeat here, what I have 
already stated of the Infusoria, when considering the case of Protozoa; neither is it 
necessary to urge again the propriety of removing the Worms from among Radiata, 
and connecting them with Articulata. There would thus remain only three classes 
among Radiates, - Polypi, Acalephs, and Echinoderms, - which, in my opinion, con- 
stitute really three natural classes in this great division, inasmuch as they exhibit 
the three different ways in which the characteristic plan of the type, radiation, 
is carried out, in distinct structures. 
Since it can be shown that Echinoderms are, in a general way, homologous 
in their structure with Acalephs and Polypi, it must be admitted that these classes 
belong to one and the same great type, and that they are the only representa- 
tives of the branch of Radiata, assuming of course that Bryozoa, Corallime, Sponges, 
and all other foreign admixtures have been removed from among Polyps. Now, 
it is this Cuvierian type of Radiata, thus freed of all its heterogeneous elements, 
which Leuckart undertakes to divide into two branches, each of which he considers 
coequal with Worms, Articulates, Mollusks, and Vertebrates. He was undoubtedly 
led to this exaggeration of the difference existing between Echinoderms on one 
side and Acalephs and Polypi on the other, by the apparently greater resemblance 
of Medusae and Polypi,1 and perhaps still more by the fact, that so many genuine 
Acalephs, such as the Hydroids, including Tubularia, Sertularia, Campanularia, etc., 
are still comprised by most zoologists in the class of Polypi. 
1 We see here clearly how the consideration of 
anatomical differences which characterize classes has 
overridden the primary feature of branches, their 
plan, to exalt a class to the rank of a branch. 184 
ESSAY ON CLASSIFICATION. 
Part I. 
But since the admirable investigations of J. Muller have made us familiar with 
the extraordinary metamorphosis of Echinoderms, and since the Ctenophorm and 
the Siphonophorm have also been more carefully studied by Grube, Leuckart, 
Kblliker, Vogt, Gegenbaur, and myself, the distance which seemed to separate Echino- 
derms from Acalephs disappears entirely, for it is no exaggeration to say, that 
were the Pluteus-like forms of Echinoderms not known to be an early stage in 
the transformation of Echinoderms, they would find as natural a place among 
Ctenophorae, as the larvae of Insects among Worms. I therefore maintain, that 
Polypi, Acalephs, and Echinoderms constitute one indivisible primary group of the 
animal kingdom. The Polypoid character of young Medusa? proves this as plainly 
as the Medusoid character of young Echinoderms. 
Further, nothing can be more unnatural than the transfer of Ctenophorae to 
the type of Mollusks which Vogt has proposed, for Ctenophorae exhibit the closest 
homology with the other Medusae, as I have shown in my paper on the Beroid 
Medusae of Massachusetts. The Ctenophoroid character of young Echinoderms 
establishes a second connection between Ctenophorae and the other Radiata, of as 
great importance as the first. We have thus an anatomical link to connect the 
Ctenophorae with the genuine Medusae, and an embryological link to connect them 
with the Echinoderms. 
The classification of Radiata may, therefore, stand thus: - 
1st Class: Polypi; including two orders, the Actinoids and the Ilalcyo- 
noids, as limited by Dana. 
2d Class: Acalephae; with the following orders: Hydroids, (including Sipho- 
nophorae,) Discophorae, and Ctenophorae. 
3d Class: Echinoderms; with Crinoids, Asteroids, Echinoids, and Holothu- 
rioids, as orders. 
The natural limits of the branch of Mollusks are easily determined. Since the 
Cirripeds have been removed to the branch of Articulata, naturalists have generally 
agreed to consider, with Cuvier, the Cephalopods, Pteropods, Gasteropods, and 
Acephala as forming the bulk of this type, and the discrepancies between modern 
investigators have mainly resulted from the views they have taken respecting the 
Bryozoa, which some consider still as Polyps, while others would unite them with 
the Worms, though their affinity with the Mollusks seems to me to have been 
clearly demonstrated by the investigations of Milne-Edwards. Vogt is the only 
naturalist -who considers the Cephalopoda "as built upon a plan entirely peculiar;1 
though he does not show in what this peculiarity of plan consists, but only mentions 
the well-known anatomical differences which distinguish them from the other classes 
1 Vogt, (C.,) Zoologisclie Briefe, q. a.; vol. 1, p. 361. Chap. HI. 
185 
MODERN SYSTEMS. 
of the branch of Mollusks. These differences, however, constitute only class charac- 
ters and exhibit in no way a different plan. It is, indeed, by no means difficult 
to homologize all the systems of organs of the Cephalopods with those of the 
other Mollusks, and with this evidence, the proof is also furnished that the Cepha- 
lopods constitute only a class among the Mollusks. 
As to the differences in the development of the Cephalopods and the other 
Mollusks, the type of Vertebrata teaches us that partial and total segmentation 
of the yolk are not inconsistent with unity of type, as the eggs of Mammalia and 
Cyclostomata undergo a total segmentation, while the process of segmentation is 
more or less limited in the other classes. In Birds, Reptiles, and Selachians, the 
segmentation is only superficial; in Batrachians, and most Fishes, it is much deeper; 
and yet no one would venture to separate the Vertebrata into several distinct 
branches on that account. With reference to Bryozoa, there can be no doubt, 
that their association with Polypi or with Worms is contrary to their natural 
affinities. The plan of their structure is in no way radiate; it is, on the con- 
trary, distinctly and essentially bilateral; and as soon as their close affinities with 
the Brachiopods, alluded to above,1 are fully understood, no doubt will remain of 
their true relation to Mollusks. As it is not within the limits of my plan to 
illustrate here the characters of all the classes of the animal kingdom, I will only 
state further, that the branch of Mollusks appears to me to contain only three 
classes, as follows: - 
1st Class: Acephala; wifh four orders, Bryozoa, including the Vorticelhe, Bra- 
chiopods, Tunicata, and Lamellibranchiata. 
2d Class: Gasteropoda; with three orders, Pteropoda, Heteropoda, and Gas- 
teropoda proper. 
3d Class: Cephalopoda; with two orders, Tetrabranchiata and Dibranchiata. 
The most objectionable modification introduced in the general classification of 
the animal kingdom, since the appearance of Cuvier's Regne Animal, seems to 
me to be the establishment of a distinct branch, now very generally admitted 
under the name of Vermes, including the Annulata, the Helminths, the Rotifera, 
and as Leuckardt would have it, the Bryozoa also. It was certainly an improve- 
ment upon Cuvier's system, to remove the Helminths from the type of Radiates, 
but it was at the same time as truly a retrograde step to separate the Annelides 
from the branch of Articulata. The most minute comparison does not lead to the 
discovery of a distinct plan of structure, uniting all these animals into one natural 
primary group. What holds them together and keeps them at a distance2 from 
other groups is not a common plan of structure, but a greater simplicity in their 
1 Chap. I., Sect. 18, p. 72. 
2 Chap. IL, Sect. 7, p. 171, 172. 186 
ESSAY ON CLASSIFICATION. 
Part I. 
organization.1 In bringing these animals together, naturalists make again the same 
mistake which Cuvier committed, when he associated the Helminths with the 
Radiates, only in another way and upon a greater scale.2 The Bryozoa are as it 
were depauperated Mollusks, as Aphanes and Alchemilla are depauperated Rosacece. 
Rotifera are in the same sense the lowest Crustacea; while Helminths and Annelides 
constitute together the lowest class of Articulata. This class is connected by the 
closest homology with the larval states of Insects; the plan of their structure is 
identical, and there exists between them only such structural differences as con- 
stitute classes.3 Moreover, the Helminths are linked to the Annelides in the same 
manner as the apodal larvae of Insects are to the most highly organized cater- 
pillars. It may truly be said that the class of Worms represents, in perfect animals, 
the embryonic states of the higher Articulata. The two other classes of this 
branch are the Crustacea and the Insects, respecting the limits of which, as much 
has already been said above,4 as is necessary to state here. 
The classification of the branch of Articulata may, therefore, stand thus: - 
1st Class: Worms; with three orders, Trematods, (including Cestods, Planariae, 
and Leeches,) Nematoids, (including Acanthocephala and Gordiacei,) and Annelides. 
2d Class: Crustacea; with four orders, Rotifera, Entomostraca, (including 
Cirripeds,) Tetradecapods, and Decapods. 
3d Class: Insects; with three orders, Myriapods, Arachnids, and Insects 
proper. 
There is not a dissenting voice among anatomists respecting the natural limits 
of the Vertebrata, as a branch of the animal kingdom. Their character, however, 
does not so much consist in the structure of their backbone or the presence of 
a dorsal cord, as in the general plan of that structure, which exhibits a cavity 
above and a cavity below a solid axis. These two cavities are circumscribed by 
complicated arches, arising from the axis, which are made up of different systems 
of organs, the skeleton, the muscles, vessels, and nerves, and include, the upper 
one the centres of the nervous system, the lower one the different systems of 
organs by which assimilation and reproduction are carried on. 
The number and limits of the classes of this branch are not yet satisfactorily 
ascertained. At least, naturalists do not all agree about them. For my part, I 
believe that the Marsupialia cannot be separated from the Placental Mammalia, 
as a distinct class, since we observe, within the limits of another type of Verte- 
brata, the Selachians, which cannot be subdivided into classes, similar differences in 
the mode of development to those which exist between the Marsupials and the other 
1 See above, Chap. I., Sect. 18, p. 74-78. 
2 Compare Chap. II., Sect. 1, p. 142. 
8 Compare Chap. II., Sect. 2, p. 145. 
4 Compare Chap. I., Sect. 18, p. 78-80. Chap. III. 
EARLY ATTEMPTS. 
187 
Mammalia. But I hold, at the same time, with other naturalists, that the Batrachia 
must be separated, as a class, from the true Reptiles, as the characters which distin- 
guish them are of the kind upon which classes are founded. I am also satisfied 
that the differences which exist between the Selachians, (the Skates, Sharks, and 
Chimserae,) are of the same kind as those which distinguish the Amphibians from 
the Reptiles proper, and justify, therefore, their separation, as a class, from the 
Fishes proper. I consider also the Cyclostomes as a distinct class, for similar 
reasons; but I am still doubtful whether the Ganoids should be separated also from 
the ordinary Fishes. This, however, cannot be decided until their embryological 
development has been thoroughly investigated, though I have already collected data 
which favor this view of the case. Should this expectation be realized, the branch 
of Vertebrata would contain the following classes: - 
1st Class: Myzontes; with two orders, Myxinoids and Cyclostomes. 
2d Class: Fishes proper; with two orders, Ctenoids and Cycloids. 
3d Class: Ganoids; with three orders, Coelacanths, Acipenseroids, and Sauroids; 
and doubtful, the Siluroids, Plectognaths, and Lophobranches. 
4th Class: Selachians; with three orders, Chimaeras, Galeodes, and Batides. 
5th Class: Amphibians; with three orders, Caeciliae, Ichthyodi, and Anura. 
6th Class: Reptiles; with four orders, Serpentes, Saurii, Rhizodontes, and 
Testudinata. 
7th Class: Birds; with four orders, Natatores, Grallas, Rasores, and Insessores, 
(including Scansores and Accipitres.) 
8th Class: Mammalia; with three orders, Marsupialia, Herbivora, and Car- 
nivora. 
I shall avail myself of an early opportunity to investigate more fully how 
far these groups of Vertebrata exhibit such characters as distinguish classes, and I 
submit my present impressions upon this subject, rather as suggestions for further 
researches, than as matured results. 
SECTION II. 
EARLY ATTEMPTS TO CLASSIFY ANIMALS. 
So few American naturalists have paid special attention to the classification 
of the animal kingdom in general, that I deem it necessary to allude to the 
different principles which, at different times, have guided zoologists in their attempts 
to group animals according to their natural affinities. This will appear the more 188 
ESSAY ON CLASSIFICATION. 
Part I. 
acceptable, I hope, since few of our libraries contain even the leading works of 
our science, and many zealous students are thus prevented from attempting to study 
what has thus far been done. 
Science has begun, in the introduction of names, to designate natural groups 
of different value with the same vagueness which still prevails in ordinary lan- 
guage in the use of class, order, genus, family, species; taking them either as 
synonyms or substituting one for the other at random. Linnaeus was the first 
to urge upon naturalists precision in the use of four kinds of groups in natural 
history, which he calls classes, orders, genera, and species. 
Aristotle, and the ancient philosophers generally, distinguished only two kinds 
of groups among animals, ytvog and (genus and species.) But the term genus 
had a most unequal meaning, applying at times indiscriminately to any extensive 
group of species, and designating even what we now call classes as well as any 
other minor group. In the sense of class, it is taken in the following case: 
Zt/oj Si yivo$, oiov oQvi&a, xdi (Arist. Hist. Anim., Lib. I., Chap. I.;) while tiSog is 
generally used for species, as the following sentence shows: xai egtlv dSq Tti.tiw i^vcov 
xdi oqviOw, though it has occasionally also a wider meaning. The sixth chapter of 
the same book, is the most important in the whole work of Aristotle upon this 
subject, as it shows to how many different kinds of groups the term jAos is applied. 
Here, he distinguishes between ym; and ytr^ wdla and yivo^ shortly, rivy St 
piyioTa twv "Qdojv, tig it Siaioehat Talika tuS' tOTiv • tv piv oqvI&wv, tv S' iy&vwv, d).).o St xigovg. 
slUo Si yivog tau to tcov oGToctxoSdficov Tdv St i.omcov ovx tart rd yivrt ptydi.a • ov yaQ 
ntQititi nolld tlSri tv tiSog,.... rd S' tyti [itv, dl/' dvmvvfia. This is further insisted upon anew: 
too St ytvovg rat TtT^anoSav xdi ^wcotoxwv e'iSi] [itv slot noild, dvdwpa St. Here tiSog has 
evidently a wider meaning than our term species, and the accurate Scaliger translates 
it by genus medium, in contradistinction to ytvog, which he renders by genus summum. 
EiSog, however, is generally used in the same sense as now, and Aristotle already 
considers fecundity as a specific character, when he says, of the Hemionos, that 
it is called so from its likeness to the Ass, and not because it is of the same 
species, for he adds, they copulate and propagate among themselves: di xai.ovvTai 
ijfuovot Si ofioioTqra, ovx ovoat dni-dg to ai'TO dSog • xdi yd(t o^evovrat xdi ytvvdvTai t^ d).).i}MV. In 
another passage it applies, however, to a group exactly identical with our modern 
genus Equus: inti Igtiv tv ti yivog xdi ini Toig t/ovoi yaiTnv, XoiyovQOig xalovfiivotg, oiov innco xdi 
ovw xdi OQti xai yivvip xdi two) xdi Toig iv xalovgivatg ^fuovoig. 
Aristotle cannot be said to have proposed any regular classification. He speaks 
constantly of more or less extensive groups, under a common appellation, evidently 
considering them as natural divisions; but he nowhere expresses a conviction that 
these groups may be arranged methodically so as to exhibit the natural affinities 
of animals. Yet he frequently introduces his remarks respecting different animals Chap. III. 
PERIOD OF LINNAEUS. 
189 
in such an order and in such connections as clearly to indicate that he knew their 
relations. When speaking of Fishes, for instance, he never includes the Selachians. 
After Aristotle, the systematic classification of animals makes no progress for 
two thousand years, until Linnaeus introduces new distinctions and assigns a more 
precise meaning to the terms class, {genus summum,) order, {genus intermedium,') genus, 
{genus proximum,) and species, the two first of which are introduced by him for the 
first time as distinct groups, under these names, in the system of Zoology. 
SECTION III. 
PERIOD OF LINNJEUS. 
When looking over the "Systema Naturae" of Linnaeus, taking as the standard 
of our appreciation even the twelfth edition, which is the last he edited himself, 
it is hardly possible, in our day, to realize how great was the influence of that 
work upon the progress of Zoology.1 And yet it acted like magic upon the age, 
and stimulated to exertions far surpassing any thing that had been done in pre- 
ceding centuries. Such a result must be ascribed partly to the circumstance that 
he was the first man who ever conceived distinctly the idea of expressing in a 
definite form, what he considered to be a system of nature, and partly also to 
the great comprehensiveness, simplicity, and clearness of his method. Discarding 
in his system every thing that could not easily be ascertained, he for the first time 
divided the animal kingdom into distinct classes, characterized by definite features; 
he also for the first time introduced orders into the system of Zoology besides 
genera and species, which had been vaguely distinguished before.2 And though 
he did not even attempt to define the characteristics of these different kinds of 
groups, it is plain, from his numerous writings, that he considered them all as 
subdivisions of a successively more limited value, embracing a larger or smaller 
number of animals, agreeing in more or less comprehensive attributes. He expresses 
1 To appreciate correctly the successive improve- 
ments of the classification of Linnaeus, we need only 
compare the first edition of the " Systema Naturae," 
published in 1735, with the second, published in 1740, 
the sixth published in 1748, the tenth published in 
1758, and the twelfth published in 1766, as they are 
the only editions he revised himself. The third is 
only a reprint of the first, the fourth and fifth are 
reprints of the second; the seventh, eighth, and ninth 
are reprints of the sixth; the eleventh is a reprint of 
the tenth; and the thirteenth, published after his 
death, by Gmelin, is a mere compilation, deserving 
little confidence. 
2 See above, Sect. 2, p. 188. The ytvrj [ifyiova 
of Aristotle correspond, however, to the classes of 
Linnaeus; the 7 A?/ peyd).a to his orders. 190 
ESSAY ON CLASSIFICATION. 
Part I. 
his views of these relations between classes, orders, genera, species, and varieties, 
by comparisons, in the following manner: -1 
Classis. 
Genus summum. 
Provinciae. 
Legiones. 
Ordo. 
Genus intermedium. 
Territoria. 
Cohortes. 
Genus. 
Genus proximum. 
Paroeciae. 
Manipuli. 
Species. 
Species. 
Pagi. 
Contubernia. 
Varietas. 
Individuum. 
Domicilium. 
Miles. 
His arrangement of the animal kingdom is presented in the following diagram, 
compiled from the twelfth edition, published in 1766. 
CLASSIFICATION OF LINNEUS. 
Cl. 1. Mammalia. Ord. Primates, Bruta, Ferae, Glires, Pecora, Belluae, Cete. 
Cl. 2. A v e s. Ord. Accipitres, Picae, Anseres, Grallae, Gallinae, Passeres. 
Cl. 3. Amphibia. Ord. Reptiles, Serpentes, Nantes. 
Cl. 4. Pisces. Ord. Apodes, Jugulares, Thoracici, Abdominales. 
Cl. 5. Insecta. Ord. Coleoptera, Hemiptera, Lepidoptera, Neuroptera, Hymenoptera, Diptera, 
Aptera. 
Cl. 6. Vermes. Ord. Intestina, Mollusca, Testacea, Lithophyta, Zoophyta. 
In the earlier editions, up to the tenth, the class of Mammalia was called 
Quadrupedia, and did not contain the Cetaceans, which were still included among 
the Fishes. There seems never to have existed any discrepancy among naturalists 
respecting the natural limits of the class of Birds, since it was first characterized 
by Linnaeus, in a manner which excluded the Bats and referred them to the class 
of Mammalia. In the early editions of the " Systema Naturae," the class of Reptiles 
embraces the same animals as in the systems of the most recent investigators; 
but since the tenth edition, it has been encumbered with the addition of the 
cartilaginous and semicartilaginous Fishes, a retrograde movement suggested by some 
inaccurate observations of Dr. Garden. The class of Fishes is very well limited 
in the early editions of the Systema, with the exception of the admission of the 
Cetaceans, (Plagiuri,) which were correctly referred to the class of Mammalia, in 
the tenth edition. In the later editions, however, the Cyclostoms, Plagiostoms, 
Chimaera?, Sturgeons, Lophioids, Discoboli, Gymnodonts, Scleroderms, and Lopho- 
branches are excluded from it and referred to the class of Reptiles. The class 
of Insects,2 as limited by Linnaeus, embraces not only what are now considered as 
1 See Systema Naturae, 12th edit., p. 13. 
2 Aristotle divides this group more correctly than 
Linnaeus, as he admits already two classes, (/aw; 
pfyuytd) among them, the Malacostraca, (Crustacea,) 
and the Entoma, (Insects.) Hist. Anim., Chap. VI. 
He seems also to have understood correctly the 
natural limits of the classes of Mammalia and Rep- 
tiles, for he distinguishes the Viviparous and Ovipa- 
rous Quadrupeds, and nowhere confounds Fishes with 
Reptiles. Ibid. Chap. III. 
191 
PERIOD OF LINNAEUS. 
Insects proper, but also the Myriapods, the Arachnids, and the Crustacea; it 
corresponds more accurately to the division of Arthropoda of modern systematists. 
The class of Worms, the most heterogeneous of all, includes besides all Radiata 
or Zoophytes and the Mollusks of modern writers, also the Worms, intestinal and 
free, the Cirripeds, and one Fish, (Myxine.) It was left for Cuvier1 to introduce 
order in this chaos. 
Such is, with its excellences and short-comings, the classification which has given 
the most unexpected and unprecedented impulse to the study of Zoology. It is 
useful to remember how lately even so imperfect a performance could have so 
great an influence upon the progress of science, in order to understand why it is 
still possible that so much remains to be done in systematic Zoology. Nothing, 
indeed, can be more instructive to the student of Natural History, than a careful 
and minute comparison of the different editions of the " Systema Naturae " of 
Linnaeus, and of the works of Cuvier and other prominent zoologists, in order to 
detect the methods by which real progress is made in our science. 
Since the publication of the " Systema Naturae " up to the time when Cuvier 
published the results of his anatomical investigations, all the attempts at new classi- 
fications were, after all, only modifications of the principles introduced by Linnaeus 
in the systematic arrangement of animals. Even his opponents labored under the 
influence of his master spirit, and a critical comparison of the various systems 
which were proposed for the arrangement of single classes or of the whole animal 
kingdom shows that they were framed according to the same principles, namely, 
under the impression that animals were to be arranged together into classes, orders, 
genera, and species, according to their more or less close external resemblance. 
No sooner, however, had Cuvier presented to the scientific world his extensive 
researches into the internal structure of the whole animal kingdom, than naturalists 
vied with one another in their attempts to remodel the whole classification of 
animals, establishing new classes, new orders, new genera, describing new species, 
and introducing all manner of intermediate divisions and subdivisions under the 
name of families, tribes, sections, etc. Foremost in these attempts was Cuvier 
himself, and next to him Lamarck. It has, however, often happened that the 
divisions introduced by the latter under new names, were only translations into 
a more systematic form of the results Cuvier had himself obtained from his dis- 
sections and pointed out in his " Legons sur 1'anatomie compare," as natural divisions, 
but without giving them distinct names. Cuvier himself beautifully expresses the 
1 It would be injustice to Aristotle not to mention 
that he understood already the relations of the animals 
united in one class by Linnaeus, under the name of 
Worms, better than the great Swedish naturalist. 
Speaking, for instance, of the great genera or classes, 
he separates correctly the Cephalopods from the 
other Mollusks, under the name of Malakia. Hist. 
Anim., Lib. I., Chap. VI. 192 
ESSAY ON CLASSIFICATION. 
Part I. 
influence which his anatomical investigations had upon Zoology, and how the 
improvements in classification have contributed to advance comparative anatomy, 
when he says, in the preface to the " Regne Animal," page vi.: "Je dus done, et 
cette obligation me prit un temps considerable, je dus faire marcher de front 
1'anatomie et la zoologie, les dissections et le classement; chercher dans mes pre- 
mieres remarques sur 1'organisation, des distributions meilleures; m'en servir pour 
arriver a des remarques nouvelles; employer encore ces remarques a perfectionner 
les distributions; faire sortir enfin de cette fecondation mutuelle des deux sciences 
Pune par Pautre, un systeme zoologique propre a servir d ' introducteur et de guide 
dans le champ de 1'anatomie, et un corps de doctrine anatomique propre a servir 
de developpement et d'explication au systeme zoologique." 
Without entering into a detailed account of all that was done in this period 
towards improving the system of Zoology, it may suffice to say, that before the 
first decade of this century had passed, more than twice as many classes as Linnaeus 
adopted had been characterized in this manner. These classes are: the Mollusks, 
Cirripeds, Crustacea, Arachnids, Annelids, Entozoa, (Intestinal Worms,) Zoophytes, 
Radiata, Polyps, and Infusoria. Cuvier1 admitted at first only eight classes, Dumeril2 
nine, Lamarck3 eleven and afterwards fourteen. The Cephalopoda, Gasteropoda, and 
Acephala, first so named by Cuvier, are in the beginning considered by him as 
orders only in the class of Mollusks; the Echinoderms also, though for the first 
time circumscribed by him within their natural limits, constitute only an order of 
the class of Zoophytes, not to speak of the lowest animals, which, from want of 
knowledge of their internal structure, still remain in great confusion. In this rapid 
sketch of the farther subdivisions which the classes Insecta and Worms of Linnaeus 
have undergone under the influence of Cuvier, I have not, of course, alluded to 
the important contributions made to our knowledge of isolated classes, by special 
writers, but limited my remarks to the works of those naturalists who have con- 
sidered the subject upon the most extensive scale. 
Thus far, no attempt had been made to combine the classes among themselves 
into more comprehensive divisions, under a higher point of view, beyond that of 
dividing the whole animal kingdom into Vertebrata and Invertebrata, a division 
which corresponds to that of Aristotle, into eraipa and avatpa. All efforts 
were rather directed towards establishing a natural series, from the lowest Infusoria 
up to Man; which, with many, soon became a favorite tendency, and ended by 
being presented as a scientific doctrine by Blainville. 
1 Cuvier, (G.,) Tableau elementaire de 1'Histoire 
naturelle des Animaux, Paris, 1798, 1 vol. 8vo. 
2 Dumeril, (A. M. C.,) Zoologie analytique, etc., 
Paris, 1806, 1 vol. 8vo. 
3 Lamarck, (J. B. de,) Systeme des Animaux 
sans'Vertebres ou Tableau general, etc., Paris, 1801, 
1 vol. 8vo. - Histoire naturelie des Animaux sans 
Vertebres, etc.. Paris, 1815-1822, 7 vote. 8vo. Chap. III. 
PERIOD OF CUVIER. 
193 
SECTION IV. 
PERIOD OF CUVIER, AND ANATOMICAL SYSTEMS. 
The most important period in the history of Zoology begins, however, with the 
year 1812, when Cuvier laid before the Academy of Sciences in Paris the results 
of his investigations upon the more intimate relations of certain classes of the 
animal kingdom to one another,1 which had satisfied him that all animals are con- 
structed upon four different plans, or, as it were, cast in four different moulds. 
A more suggestive view of the subject never was presented before to the appre- 
ciation of investigators; and, though it has by no means as yet produced all the 
results which certainly are to flow from its further consideration, it has already led 
to the most unquestionable improvements which classification in general has made 
since the days of Aristotle, and, if I am not greatly mistaken, it is only in as 
far as that fundamental principle has been adhered to that the changes proposed 
in our systems, by later writers, have proved a real progress, and not as many retro- 
grade steps. 
This great principle, introduced into our science by Cuvier, is expressed by him 
in these memorable words: "Si 1'on considere le regne animal d'apres les prin- 
cipes que nous venons de poser, en se debarrassant des prejuges etablis sur les 
divisions anciennement admises, en n'ayant egard qu'a 1'organisation et a la nature 
des animaux, et non pas a leur grandeur, a leur utilite, au plus ou moins de 
connaissance que nous en avons, ni a toutes les autres circonstances accessoires, on 
trouvera qu'il existe quatre formes principales, quatre plans generaux, si 1'on peut 
s'exprimer ainsi, d'apres lesquels tous les animaux semblent avoir ete modeles et 
dont les divisions ulterieures, de quelque titre que les naturalistes les aient deco- 
rees, ne sont que des modifications assez legeres fondees sur le developpement ou 
1'addition de quelques parties, qui ne changent rien a 1'essence du plan." 
It is therefore incredible to me how, in presence of such explicit expressions, 
Cuvier can be represented, as he is still occasionally, as favoring a division of 
the animal kingdom into Vertebrata and Invertebrata.2 Cuvier, moreover, was the 
first to recognize practically the inequality of all the divisions he adopts in his 
system; and this constitutes further a great and important step, even though he 
may not have found the correct measure for all his groups. For we must remem- 
ber that at the time he wrote, naturalists were bent upon establishing one con- 
1 Ann. du Museum d'Histoire Naturelie, vol. xix., 
Paris, 1812. 
2 Ehrenberg, (C. G.,) Die Corallenthiere des 
rothen Meeres, Berlin, 1834, 4to., p. 30, note. 194 
ESSAY ON CLASSIFICATION. 
Part I. 
tinual uniform series to embrace all animals, between the links of which it was 
supposed there were no unequal intervals. The watchword of their school was: 
Natura non facit saltum. They called their system la chaine des etres. 
The views of Cuvier led him to the following arrangement of the animal 
kingdom: - 
CLASSIFICATION OF CUVIER.1 
First Branch. Animalia Vertebrata. 
Cl. 1. Mammalia. Orders'. Bimana, Quadrumana, Carnivora, Marsupialia, Rodentia, Eden- 
tata, Pachydermata, Ruminantia, Cetacea. 
Cl. 2. Birds. Ord. Accipitres, Passeres, Scansores, Gallina?, Grallae, Palmipedes. 
Cl. 3. R e p t i 1 i a. Ord. Chelonia, Sauria, Ophidia, Batrachia. 
Cl. 4. Fishes. 1st Series: Fishes proper. Ord. Acanthopterygii; - Abdominales, Sub- 
brachii, Apodes ; - Lophobranchii, Plectognathi; 2d Series : Chondropterygii. 
Ord. Sturiones, Selachii, Cyclostomi.2 
Second Branch. Animalia Mollusca. 
Cl. 1. Cephalopoda. No subdivisions into orders or families. 
Cl. 2. Pteropoda. No subdivisions into orders or families. 
Cl. 3. Gasteropoda. Ord. Pulmonata, Nudibranchia, Inferobranchia, Tectibranchia, Hetero- 
poda, Pectinibranchia, Tubulibranchia, Scutibranchia, Cyclobranchia. 
Cl. 4. A c e p h a 1 a . Ord. Testacea, Tunicata. 
Cl. 5. B r a c h i o p o d a. No subdivisions into orders or families. 
Cl. 6. C i r r h o p o d a. No subdivisions into orders or families. 
Third Branch. Animalia Articulata. 
Cl. 1. Annelides. Ord. Tubicolae, Dorsibranchiae, Abranchiae. 
Cl. 2. Crustacea. 1 sf Section : M a 1 a c o s t r a c a. Ord. Decapoda, Stomapoda, Amphipoda, 
Laemodipoda, Isopoda. 2d Section: Entomostraca. Ord. Branchiopoda, Poecilopoda, 
Trilobitse. 
Cl. 3. Arachnides. Ord. Pulmonariae, Tracheariae. 
Cl. 4. Insects. Ord. Myriapoda, Thysanura, Parasita, Suctoria, Coleoptera, Orthoptera, 
Hemiptera, Neuroptera, Hymenoptcra, Lepidoptera, Rhipiptera, Diptera. 
Fourth Branch. Animalia Radi ata. 
Cl. 1. Echinoderms. Ord. Pedicellata, Apoda. 
Cl. 2. Intestinal Worms. Ord. Nematoidea, (inch Epizoa and Entozoa,) Parenchymatosa. 
Cl. 3. Acalephae. Ord. Simplices, Hydrostatic®. 
Cl. 4. Polypi. (Including Anthozoa, Hydroids, Bryozoa, Corallime, and Spongiae.) Ord. 
Carnosi, Gelatinosi, Polypiarii. 
Cl. 5. Infusoria. Ord. Rotifera and Ilomogenea, (including Polygastrica and some Algae.) 
1 Le Regno animal distribue d'aprcs son organisation, Paris, 
1829, 2de edit. 5 vols. 8vo. The classes of Crustacea, Arach- 
nids, and Insects have been elaborated by Latreille. For the 
successive modifications the classification of Cuvier has under- 
gone, compare his Tableau elementaire, q. a., p. 192, his paper, 
q. a., p. 193, and the first edition of the Regno animal, published 
in 1817, in 4 vols. 8vo. 
2 Comp. Regn. Anim., 2de edit., 2d vol., p. 128 and 383. Chap. III. 
PERIOD OF CUVIER. 
195 
When we consider the zoological systems of the past century, that of Lin- 
naeus, for instance, and compare them with more recent ones, that of Cuvier, for 
example, we cannot overlook the fact, that even when discoveries have added little 
to our knowledge, the subject is treated in a different manner; not merely in 
consequence of the more extensive information respecting the internal structure of 
animals, but also respecting the gradation of the higher groups. 
Linnaeus had no divisions of a higher order than classes. Cuvier introduced, 
for the first time, four great divisions, which he called "embranchemens" or branches, 
under which he arranged his classes, of which he admitted three times as many as 
Linnaeus had done. 
Again, Linnaeus divides his classes into orders; next, he introduces genera, and 
finally, species; and this he does systematically in the same gradation through all 
classes, so that each of his six classes is subdivided into orders, and these into 
genera with their species. Of families, as now understood, Linnaeus knows nothing. 
The classification of Cuvier presents no such regularity in its framework. In 
some classes he proceeds, immediately after presenting their characteristics, to the 
enumeration of the genera they contain, without grouping them either into orders 
or families. In other classes, he admits orders under the head of the class, and 
then proceeds to the characteristics of the genera, while in others still, he admits 
under the class not only orders and families, placing always the family in a sub- 
ordinate position to the order, but also a number of secondary divisions which 
he calls sections, divisions, tribes, etc., before he reaches the genera and species. 
With reference to the genera again, we find marked discrepancies in different 
classes. Sometimes a genus is to him an extensive group of species, widely differ- 
ing one from the other, and of such genera he speaks as "grands genres;" others 
are limited in their extent, and contain homogeneous species without farther sub- 
divisions, while still others are subdivided into what he calls sub-genera, and this 
is usually the case with his " great genera." 
The gradation of divisions with Cuvier varies then with his classes, some classes 
containing only genera and species, and neither orders nor families nor any other 
subdivision. Others contain orders, families, and genera, and besides these, a variety 
of subdivisions of the most diversified extent and significance. This remarkable 
inequality between all the divisions of Cuvier is, no doubt, partly owing to the 
state of Zoology and of zoological museums at the time he wrote, and to his 
determination to admit into his work only such representatives of the animal 
kingdom as he could to a greater or less extent examine anatomically for him- 
self ; but it is also partly to be ascribed to his conviction, often expressed, that 
there is no such uniformity or regular serial gradation among animals as many 
naturalists attempted to introduce into their classifications. 196 
ESSAY ON CLASSIFICATION. 
Part I. 
CLASSIFICATION OF LAMARCK. 
Histoire naturelie des Animaux sans vertebres, etc., Paris, 1815-1822, 7 vols. 8vo. - A second edition with notes has been pub- 
lished by Messrs. DesIIayes and Milne-Edwards, Paris, 1835-1843, 10 vols. 8vo.-For the successive modifications this classi- 
fication has undergone, see also : Systeme des animaux sans vertebres, etc., Paris, 1801, 8vo.-Philosophic zoologique, etc., Paris, 
1809, 2 vols. 8vo. - Extrait du Cours de Zoologie du Museum d'Histoire naturelie, etc., Paris, 1812, 8vo. 
INVERTEBRATA. 
I. Apathetic Animals. 
Cl. 1. Infusoria. Ord. Nuda, Appendiculata. 
Cl. 2. Polypi. Ord. Ciliati (Rotifera), Denudati (Hydroids), 
Vaginati (Anthozoa and Bryozoa), and Natantes (Crinoids, 
and some Halcyonoids.) 
Cl. 3. R ad i a r i a. Ord. Mollia (Acalephas), Echinoderms, (includ- 
ing Holothuriae and Actiniae.) 
Cl. 4. Tunicata. Ord. Bothryllaria (Compound Ascidians), 
Ascidia, (Simple Ascidians.) 
Cl. 5. V e r in e s . Ord. Molies and Rigiduli (Intestinal Worms and 
Gordius), Hispiduli (Nais), Epizoariae (Epizoa, Lernaeans.) 
Do not feel, and move 
only by their excited irri- 
tability. No brain, nor 
elongated medullary mass ; 
no senses ; forms varied ; 
rarely articulations. 
Il. Sensitive Animals. 
Feel, but obtain from 
their sensations only per- 
ceptions of objects, a sort 
of simple ideas, which they 
are unable to combine to 
obtain complex ones. No 
vertebral column ; a brain 
and mostly an elongated 
medullary mass ; some dis- 
tinct senses; muscles at- 
tached under the skin; 
form symmetrical, the parts 
being in pairs. 
Cl. 6. Insects. (Hexapods.) Ord. Aptera, Diptera, Hemiptera, 
Lepidoptera, Hymenoptera, Nevroptera, Orthoptera, Cole- 
optera. 
Cl. 7. Arachnids. Ord. Antennato-tracheales (Thysanura and 
Myriapoda), Exantennato-tracheales and Exantennato-bran- 
chiales (Arachnids proper.) 
Cl. 8. Crustacea. Ord. Heterobranchia (Branchipoda, Isopoda, 
Amphipoda, Stomapoda) and Homobranchia (Decapoda.) 
Cl. 9. Annelids. Ord. Apoda, Antennata, Sedentaria. 
Cl. 10. Cirripeds. Ord. Sessilia and Pedunculata. 
Cl. 11. Conchifera. Ord. Dimyaria, Monomyaria. 
Cl. 12. Mollusks. Ord. Pteropoda, Gasteropoda, Trachelipoda, 
Cephalopoda, Heteropoda. 
VERTEBRATA. 
III. Intelligent Animals. 
Cl. 13. Fishes. 
Cl. 14. Reptiles. 
Cl. 15. Birds. 
Cl. 16. Mammalia. 
Feel; acquire preservable ideas; perform with them oper- 
ations by which they obtain others; are intelligent in different 
degrees. A vertebral column; a brain and a spinal marrow; 
distinct senses; the muscles attached to the internal skeleton; 
form symmetrical, the parts being in pairs. 
It is not easy to appreciate correctly the system of Lamarck, as it combines 
abstract conceptions with structural considerations, and an artificial endeavor to 
arrange all animals in continuous series. The primary subdivision of the animal 
kingdom into Invertebrata and Vertebrata1 corresponds, as I have stated above, to 
1 See, above, Chap. 2, Sect. 1, p. 138. Chap. III. 
PERIOD OF CUVIER. 
197 
that of Anaima and Enaima of Aristotle. The three leading groups designated 
under the name of Apathetic, Sensitive, and Intelligent animals, are an imitation 
of the four branches of Cuvier; but, far from resting upon such a definite idea 
as the divisions of Cuvier, which involve a special plan of structure, they are 
founded upon the assumption that the psychical faculties of animals present a serial 
gradation, which, when applied as a principle of classification, is certainly not admis- 
sible. To say that neither Infusoria, nor Polypi, nor Radiata, nor Tunicata, nor 
Worms feel, is certainly a very erroneous assertion. They manifest sensations quite 
as distinctly as many of the animals included in the second type which are called 
Sensitive. And as to the other assertion, that they move only by their excited 
irritability, we need only watch the Starfishes to be satisfied that their motions 
are determined by internal impulses and not by external excitation. Modern inves- 
tigations have shown that most of them have a nervous system, and many even 
organs of senses. 
The Sensitive animals are distinguished from the third type, the Intelligent 
animals, by the character of their sensations. It is stated, in respect to the Sensi- 
tive animals, that they obtain from their sensations only perceptions of objects, a 
sort of simple ideas which they are unable to combine so as to derive from 
them complex ones, while the Intelligent animals are said to obtain ideas which 
they may preserve, and to perform with them operations by which they arrive 
at new ideas. They are said to be Intelligent. Even now, fifty years after 
Lamarck made those assertions, I doubt whether it is possible to distinguish in 
that way between the sensations of the Fishes, for instance, and those of the 
Cephalopods. It is true, the structure of the animals called Sensitive and Intelli- 
gent by Lamarck differs greatly, but a large number of his Sensitive animals are 
constructed upon the same plan as many of those he includes among the Apathetic; 
they embrace, moreover, two different plans of structure, and animal psychology 
is certainly not so far advanced as to afford the least foundation for the distinc- 
tions here introduced. 
Even from his own point of view, his arrangement of the classes is less perfect 
than he might have made it, as the Annelids stand nearer to the Worms than 
the Insects, and are very inferior to them. Having failed to perceive the value 
of the idea of plan, and having substituted for it that of a more or less com- 
plicated structure, Lamarck unites among his Apathetic animals, Radiates (the Polypi 
and Radiaria) with Mollusks, (the Tunicata,) and with Articulates (the Worms.) 
Among the Sensitive animals, he unites Articulates (the Insects, Arachnids, Crus- 
tacea, Annelids, and Cirripeds) with Mollusks (the Conchifera, and the Mollusks 
proper.) Among the Intelligent animals, he includes the ancient four classes of 
Vertebrates, the Fishes, Reptiles, Birds, and Mammalia. 198 
ESSAY ON CLASSIFICATION. 
Part I. 
CLASSIFICATION OF DE BLAINVILLE.1 
1. Sub-Kingdom. Artiomorpha or Artiozoaria. Form bilateral. 
First Type: Osteozoaria. (Vertebrata.) 
Sub-Type : Vivipara. 
Cl. 1. Pi lifer a, or Mammifera. 1st. Monadelphya. 2d. Didelphya. 
Sub-Type: Ovipara. 
Cl. 2. Pennifera, or Aves. 
Cl. 3. Squamifera, or Reptilia. 
Cl. 4. Nudipellifera,or Amphibia. 
Cl. 5. P i n n i f e r a, or Pisces. 
Anosteozoaria. 
Second Type: Entomozoaria. (Articulata.) 
Cl. 6. H e x a p o d a. (Insecta proprie sic dicta.) 
Cl. 7. Octopoda. (Arachnida.) 
Cl. 8. Decapoda. (Crustacea, Decapoda, and Limulus.) 
Cl. 9. Ileteropoda. (Squilla, Entomostraca, and Epizoa.) 
Cl. 10. Tetradecapoda. (Amphipoda and Isopoda.) 
Cl. 11. Myriapoda. 
Cl. 12. Chaetopoda. (Annelides.) 
Cl. 13. Apo da. (Hirudo, Cestoidea, Ascaris.) 
Third Type : Malentozoaria. 
Cl. 14. Nematopoda. (Cirripedia.) 
Cl. 15. P o 1 y p 1 a x i p h o r a. (Chiton.) 
Fourth Type: Malacozoaria. (Mollusca.) 
Cl. 16. C e p h al o ph o ra. Dioica, (Cephalopoda and Gasteropoda, p. p.) Herma- 
phrodita and Monoica (Gasteropoda reliqua.) 
Cl. 17. Ace ph al o pho ra. Palliobranchia (Brachiopoda), Lamellibranchia (Acephala), 
Ileterobranchia (Ascidia?.) 
2. Sub-Kingdom. Actinomorpha or Actinozoaria. Form radiate. 
Cl. 18. Annelidaria, or Gastrophysaria (Sipunculus, etc.) 
Cl. 19. C e r a t o d e r ni a r i a. (Echinodermata.) 
Cl. 20. Arachnodermaria. (Acalephae.) 
Cl. 21. Zoantharia. (Actiniae.) 
Cl. 22. Polypi a ria. (Polypi tentaculis simplicibus), (Anthozoa and Bryozoa.) 
Cl. 23. Zoophytaria. (Polypi tentaculis compositis), (Halcyonoidea.) 
3. Sub-Kingdom. Heteromorpha or Heterozoaria. Form irregular. 
Cl. 24. Spongiaria. (Spongiae.) 
Cl. 25. Monadaria. (Infusoria.) 
Cl. 26. Dendrolitharia. (Corallinae.) 
The classification of de Blainville resembles those of Lamarck and Cuvier much 
more than a diagram of the three would lead us to suppose. The first of these 
systems is founded upon the idea that the animal kingdom forms one gradated 
1 De 1'Organisation des Animaux, Paris, 1822, 1 vol. 8vo. Chap. HI. 
PERIOD OF CUVIER. 
199 
series; only that de Blainville inverts the order of Lamarck, beginning with the 
highest animals and ending with the lowest. With that idea is blended, to some 
extent, the view of Cuvier, that animals are framed upon different plans of structure; 
but so imperfectly has this view taken hold of de Blainville, that instead of 
recognizing at the outset these great plans, he allows the external form to be 
the leading idea upon which his primary divisions are founded, and thus he divides 
the animal kingdom into three sub-kingdoms: the first, including his Artiozoaria, 
with a bilateral form; the second, his Actinozoaria, with a radiated form, and the 
third, his Heterozoaria, with an irregular form (the Sponges, Infusoria, and Corallines.) 
The plan of structure is only introduced as a secondary consideration, upon which he 
establishes four types among the Artiozoaria: 1st. The Osteozoaria, corresponding to 
Cuvier's Vertebrata; 2d. The Entomozoaria, corresponding to Cuvier's Articulata; 
3d. The Malentozoaria, which are a very artificial group, suggested only by the 
necessity of establishing a transition between the Articulata and Mollusca; 4th. 
The Malacozoaria, corresponding to Cuvier's Mollusca. The second sub-kingdom, 
Actinozoaria, corresponds to Cuvier's Radiata, while the third sub-kingdom, Hetero- 
zoaria, contains organized beings which for the most part do not belong to the 
animal kingdom. Such at least are his Spongiaria and Dendrolitharia, whilst his 
Monodaria answer to the old class of Infusoria, about which enough has already 
been said above. It is evident, that what is correct in this general arrangement 
is borrowed from Cuvier; but it is only justice to de Blainville to say, that in the 
limitation and arrangement of the classes, he has introduced some valuable improve- 
ments. Among Vertebrata, for instance, he has, for the first time, distinguished 
the class of Amphibia from the true Reptiles. He was also the first to remove 
the Intestinal Worms from among the Radiata to the Articulata; but the establish- 
ment of a distinct type for the Cirripedia and Chitons was a very mistaken con- 
ception. Notwithstanding some structural peculiarities, the Chitons are built essen- 
tially upon the same plan as the Mollusks of the class Gasteropoda, and the 
investigations, made not long after the publication of de Blainville's system, have left 
no doubt that Cirripedia are genuine Crustacea. The supposed transition between 
Articulata and Mollusks, which de Blainville attempted to establish with his type of 
Malentozoaria, certainly does not exist in nature. 
If we apply to the classes of de Blainville the test introduced in the preceding 
chapter, it will be obvious that his Decapoda, Heteropoda, and Tetradecapoda par- 
take more of the character of orders than of that of classes, whilst among Mol- 
lusks, his class Cephalophora certainly includes two classes, as he has himself acknowl- 
edged in his later works. Among Radiata his classes Zoantharia, Polypiaria, and 
Zoophytaria partake again of the character of orders and not of those of classes. 
One greit objection to the system of de Blainville is, the useless introduction of so 200 
ESSAY ON CLASSIFICATION. 
Part I. 
many new names for groups which had already been correctly limited and well 
named by his predecessors. Ue had, no doubt, a desirable object in view in doing 
this, - he wished to remove some incorrect names; but he extended his reform 
too far when he undertook to change those also which did not suit his system. 
CLASSIFICATION OF EHRENBERG. 
The characteristics of the following twenty-eight classes of animals, with a twenty-ninth for Man alone, 
are given more fully in the Transactions of the Academy of Berlin for 1836, in the paper q. a., p. 138. 
1st Cycle: Nations. Mankind, constituting one distinct class, is characterized by the equable development of 
all systems of organs, in contradistinction of the 
2d Cycle: Animals, which are considered as characterized by the prominence of single systems. These are 
divided into: 
A. Myeloneura. 
I. Nutrientia. Warm-blooded Vertebrata, taking 
care of their young. 
Cl. 1. Mammalia. 
Cl. 2. Birds. 
II. Orpiianozoa. Cold-blooded Vertebrata, taking 
no care of their young. 
Cl. 3. Amphibia. 
CL 4. Pisces. 
B. Ganglioneura. 
A. Sphygmozoa, Cordata. 
Circulation marked by a heart or pulsating vessels. 
III. Articulata. Real articulation, marked by 
rows of ganglia and their ramifications. 
Cl. 5. I n s e c t a. 
Cl. 6. Araehnoidea. 
Cl. 7. Crustacea (including Entomostraca, 
Cirripedia, and Lern®a.) 
Cl. 8. Ann ulata. (The genuine Annelids 
exclusive of Nais.) 
Cl. 9. S om a t o tom a. (Naidina.) 
IV. Mollusca. No articulation. Ganglia dis- 
persed. 
Cl. 10. Cephalopoda. 
Cl. 11. Pteropoda. 
Cl. 12. Gasteropoda. 
Cl. 13. A c e p h a 1 a. 
Cl. 14. Brachiopoda. 
Cl. 15. Tunicata. (Ascidi® simplices.) 
Cl. 16. Aggregata. (Ascidi® composit®.) 
B. Asphycta, Vasculosa. 
Vessels without pulsation. 
V. Tubulata. No real articulation. Intestine, a 
simple sac or tube. 
Cl. 17. Bryozoa. 
Cl. 18. Di morph® a. (Hydroids.) 
Cl. 19. Tur bellaria. (Rhabdocoela: De- 
rostoma, Turbella, Vortex.) 
Cl. 20. Nematoidea. (Entozoa, with sim- 
ple intestine ; also Gordius and Anguillula.) 
Cl. 21. Rotatoria. 
Cl. 22. Echinoidea. (Echinus, Holothuria, 
Sipunculus.) 
VI. Racemifera. Intestine divided, or forked, ra- 
diating, dendritic, or racemose. 
Cl. 23. Asteroidea. 
Cl. 24. Acalephae. 
Cl. 25. Anthozoa. 
Cl. 26. Irematodea. (Entozoa with rami- 
fied intestine, also Cercaria.) 
Cl. 27. Complanata. (Dendrocoela: Pla- 
naria, etc.) 
Cl. 28. Polygastrica. 201 
Chap. III. 
ANATOMICAL SYSTEMS. 
The system of Zoology, published by Ehrenberg in 1836, presents many new 
views in almost all its peculiarities. The most striking of its features is the prin- 
ciple laid down, that the type of development of animals is one and the same 
from Man to the Monad, implying a complete negation of the principle advocated 
by Cuvier, that the four primary divisions of the animal kingdom are characterized 
by different plans of structure. It is very natural that Ehrenberg, after having 
illustrated so fully and so beautifully as he did, the natural history of so many 
organized beings, which up to the publication of his investigations were generally 
considered as entirely homogeneous, after having shown how highly organized and 
complicated the internal structure of many of them is, after having proved the 
fallacy of the prevailing opinions respecting their origin, should have been led to 
the conviction that there is, after all, no essential difference between these animals, 
which were then regarded as the lowest, and those which were placed at the 
head of the animal creation. The investigator, who had just revealed to the 
astonished scientific world the complicated systems of organs which can be traced 
in the body of microscopically small Rotifera, must have been led irresistibly to the 
conclusion that all animals are equally perfect, and have assumed, as a natural con- 
sequence of the evidence he had obtained, that they stand on the same level with one 
another, as far as the complication of their structure is concerned. Yet the diagram 
of his own system shows, that he himself could not resist the internal evidence of 
their unequal structural endowment Like all other naturalists, he places Mankind 
at one end of the animal kingdom, and such types as have always been considered 
as low, at the other end. 
Man constitutes, in his opinion, an independent cycle, that of nations, in contra- 
distinction to the cycle of animals, which he divides into Myeloneura, those with ner- 
vous marrow (the Vertebrata,) and Ganglioneura, those with ganglia (the Invertebrata.) 
The Vertebrata he subdivides into Nidnentia, those which take care of their young, 
and Orphanozoa, those which take no care of their young, though this is not strictly 
true, as there are many Fishes and Reptiles which provide as carefully for their 
young as some of the Birds and Mammalia, though they do it in another way. 
The Invertebrata are subdivided into Spliygmozoa, those which have a heart or 
pulsating vessels, and Asphycta, those in which the vessels do not pulsate. These 
two sections are further subdivided: the first, into Articulata with real articulations 
and rows of ganglia, and Mollusks without articulation and with dispersed ganglia; 
the second, into Tubulata with a simple intestine, and Racemifera with a branching 
intestine. These characters, which Ehrenberg assigns to his leading divisions, imply 
necessarily the admission of a gradation among animals. He thus negatives, in 
the form in which he expresses the results of his investigations, the very principle 
he intends to illustrate by his diagram. The peculiar view of Ehrenberg, that 202 
ESSAY ON CLASSIFICATION. 
Part I. 
all animals are equal in the perfection of their organization, might be justified, if 
it was qualified so as to imply a relative perfection, adapted in all to the end 
of their special mode of existence. As no one observer has contributed more 
extensively than Ehrenberg to make known the complicated structure of a host 
of living beings, which before him were almost universally believed to consist of 
a simple mass of homogeneous jelly, such a view would naturally be expected 
of him. But this qualified perfection is not what he means. He does not wish 
to convey the idea that all animals are equally perfect in their way, for he states 
distinctly that " Infusoria have the same sum of systems of organs as Man," and 
the whole of his system is intended to impress emphatically this view. The separa- 
tion of Man from the animals, not merely as a class but as a still higher division, 
is especially maintained upon that ground. 
The principle of classification adopted by Ehrenberg is purely anatomical; the idea 
of type is entirely set aside, as is shown by the respective position of his classes. 
The Myeloneura, it is true, correspond to the branch of Vertebrata, and the 
Sphygmozoa to the Articulata and Mollusca; but they are not brought together 
on the ground of the typical plan of their structure, but because the first have 
a spinal marrow and the other a heart or pulsating vessels with or without articula- 
tions of the body. In the division of Tubulata, it is still more evident how the 
plan of their structure is disregarded, as that section embraces Radiata, (the 
Echinoidea and the Dimorphsea,) Mollusca, (the Bryozoa,) and Articulata, (the 
Turbellaria, the Nematoidea, and the Rotatoria,) which are thus combined simply 
on the ground that they have vessels which do not pulsate, and that their intestine 
is a simple sac or tube. The Racemifera contain also animals constructed upon 
different plans, united on account of the peculiar structure of the intestine, which 
is either forked or radiating, dendritic or racemose. 
The limitation of many of the classes proposed by Ehrenberg is quite objec- 
tionable, when tested by the principles discussed above. A large proportion of them 
are, indeed, founded upon ordinal characters only, and not upon class characters. 
This is particularly evident with the Rotatoria, the Somatotoma, the Turbellaria, the 
Nematoidea, the Trematodea, and the Complanata, all of which belong to the branch 
of Articulata. The Tunicata, the Aggregata, the Brachiopoda, and the Bryozoa are 
also only orders of the class Acephala. Before Echinoderms had been so exten- 
sively studied as of late, the separation of the Echinoidea from Asteroidea might 
have seemed justifiable; at the present day, it is totally inadmissible. Even 
Leuckart, who considers the Echinoderms as a distinct branch of the animal king- 
dom, insists upon the necessity of uniting them as a natural group. As to the 
Dimorphsea, they constitute a natural order of the class Acalephse, which is generally 
known by the name of Hydroids. Chap. III. 
ANATOMICAL SYSTEMS. 
203 
CLASSIFICATION OF BURMEISTER. 
The following diagram is compiled from the author's Geschichte der Schopfung, Leipzig, 1843, 1 vol. 8vo. 
Type I. Irregular Animals. 
1st Subtype. Cl. 1. Infusoria. 
Type II. Regular Animals. 
2d Subtype. Cl. 2. Polypina. Ord. Bryozoa, Anthozoa. 
3d Subtype. Cl. 3. R a d i a t a. Ord. Acalephie, Echinodermata, Scytodermata. 
Type III. Symmetrical Animals. 
4th Subtype. Cl. 4. M o 11 u s c a. Ord. Perigymna (Tunicata) ; Cormopoda (Acephala) ; Brachio- 
poda, Cephalophora (Pteropoda and Gasteropoda) ; Cephalopoda. 
5th Subtype. Arthrozoa. 
Cl. 5. Vermes. Ord. Helminthes, Trematodes, and Annulati. 
Cl. 6. Crustacea. 1°. Ostracoderma. Ord. Prothesmia (Cirripedia, Siphono- 
stoma, and Rotatoria); Aspidostraca (Entomostraca: Lophyropoda, Phyllopoda, 
Piecilopoda, Trilobitae.) 2°. Malacostraca. Ord. Thoracostraca (Podoph- 
thalma) ; and Arthrostraca, (Edriophthalma.) 
Cl. 7. Arachnoda. Ord. Myriapoda, Arachnidae. 
Cl. 8. Insecta. Ord. Rhynchota, Synistata, Antliata, Piezata, Glossata, Eleutherata. 
6th Subtype. Osteozoa. (Vertebrata.) 
Cl. 9. Pisces. 
Cl. 10. Amphibia. 
Cl. 11. Aves. 
Cl. 12. Mammalia. 
The general arrangement of the classification of Burmeister recalls that of 
de Blainville; only that the order is inverted. His three types correspond to the 
three subkingdoms of de Blainville: the Irregular Animals to the Heterozoaria, the 
Regular Animals to the Actinozoaria, and the Symmetrical Animals to the Artiozo- 
aria; while his subtypes of the Symmetrical Animals correspond to the types de 
Blainville admits among his Artiozoaria, with this important improvement, however, 
that the Malentozoaria are suppressed. Burmeister reduces, unhappily, the whole 
branch of Mollusks to one single class. The Arthrozoa, on the contrary, in the 
investigation of which Burmeister has rendered eminent service to science, are pre- 
sented in their true light. In his special works,1 his classification of the Articulata 
is presented with more details. I have no doubt that the correct views he entertains 
respecting the standing of the Worms in the branch of Articulata are owing to his 
extensive acquaintance with the Crustacea and Insects, and their metamorphoses. 
1 These works are : Beitrage zur Naturgeschichte 
der Rankenfusser, (Cirripedia,) Berlin, 1834, 1 vol. 
4to. - Handbuch der Entomologie, Berlin, 1832-47, 
5 vols. 8vo.; Engl, by W. E. Shuckard, London, 
1836. - Die Organisation der Trilobiten, aus ihren 
lebenden Verwandten entwickelt, Berlin, 1843, 1 vol. 
4to.; Engl, by the Ray Society, London, 1847, 
1 vol. fol. 204 
ESSAY ON CLASSIFICATION. 
Part I. 
CLASSIFICATION OF OWEN. 
The following diagram is compiled from R. Owen's Lectures on the Comparative Anatomy and 
Physiology of the Invertebrate Animals, 2d edit., London, 1855, 1 vol. 8vo. 
Province. Vertebrata. Myelencephala. (Owen.) 
Cl. Mammalia. 
Cl. Aves. 
Cl. R e p t i 1 i a. 
The classes Mammalia, Aves, and Reptilia are not yet included in the second volume 
of the "Lectures," the only one relating to Vertebrata thus far published. 
Cl. Pisces. Ord. Dermopteri, Malacopteri, Pharyngognathi, Anacanthini, Acanthopteri, Plectognathi, 
Lophobrancliii, Ganoidei, Protopteri, Holocephali, Plagiostomi. 
Province. Articulata. Homogangliata. (Owen.) 
Cl. Arachnid a. Ord. Dermophysa, Trachearia, Pulmotrachearia, and Pulmonaria. 
Cl. I n s e c t a. Subclass: M yr i a p o d a. Ord. Chilognatha and Chilopoda. Subclass: II e x a p o d a. 
Ord. Aptera, Diptera, Lepidoptera, Hymenoptera, Homoptera, Strepsiptera, Nevroptera, Orthop- 
tera, and Coleoptera. 
Cl. Crustacea. Subclass: Entomostraca. Ord. Trilobites, Xiphosura, Phyllopoda, Cladocera, 
Ostracopoda, Copepoda. Subclass: M a 1 aco s t r ac a. 1°. Edriophthalma. Ord. Lsemodipoda, 
Isopoda, Amphipoda. 2°. Podophthahna. Ord. Stomapoda, Decapoda. 
Cl. E p i z o a. Ord. Cephaluna, Brachiuna, and Onchuna. 
Cl. Annellata. Ord. Suctoria, Terricola, Errantia, Tubicola. 
Cl. C i r r i p e d i a. Ord. Thoracica, Abdoniinalia, and Apoda. 
Province. Mollusca. Heterogangliata. (Owen.) 
Cl. Cephalopoda. Ord. Tetrabranchiata and Dibranchiata. 
Cl. Gasteropoda. A. Monoecia: Ord. Apneusta (Roll.), Nudibranchiata, Inferobranchiata, 
Tectibranchiata, Pulmonata. B. Dice ci a. Ord. Nucleobranchiata, Tubulibranchiata, Cyclo- 
branchiata, Scutibranchiata, and Pectinibranchiata. 
Cl. Pteropoda. Ord. Thecosomata and Gymnosomata. 
Cl. Lamellibranchiata. Ord. Monomyaria and Dimyaria. 
Cl. Brach iopod a. Only subdivided into families. 
Cl. T u n i c a t a. Ord. Saccobranchiata and Taeniobranchiata. 
Subprovince. Radiaria.1 
Cl. Echinoderm ata. Ord. Crinoidea, Asteroidea, Echinoidea, Ilolothurioidea, and Sipunculoidea. 
Cl. Bryozoa. Only subdivided into families. 
Cl. Anthozoa. Only subdivided into families. 
Cl. Acalephae. Ord. Puhnograda, Ciliograda, and Physograda. 
Cl. Hydro zoa. Only subdivided into families. 
Subprovince. Entozoa. 
Cl. Coelelmintha. Ord. Gordiacea, Nematoidea, and Onchophora. 
Cl. Sterelmintha. Ord. Taenioidea, Trematoda, Acanthocephala. - Turbellaria. 
Subprovince. Infusoria. 
Cl. Rotifer a. Only subdivided into families. 
Cl. Polygastria. Ord. Astoma, Stomatoda. - Rhizopoda. 
1 In the first edition of the work quoted above, published 
in 1843, the three subprovinces, Radiaria, Entozoa, and Infu- 
soria are considered as one subkingdom called Radiata, in 
contradistinction of the subkingdoms, Mollusca, Articulata, 
and Vertebrata, and that subkingdom is subdivided into two 
groups, Nematoneura and Acrita. Chap. HL 
ANATOMICAL SYSTEMS. 
205 
The classification with which Owen1 introduces his " Lectures on Comparative 
Anatomy" is very instructive, as showing, more distinctly than other modern systems, 
the unfortunate ascendency which the consideration of the complication of structure 
has gained of late over the idea of plan. His provinces, it is true, correspond 
in the main to the branches of Cuvier, with this marked difference, however, that 
he does not recognize a distinct province of Radiata coequal with those of Mollusca, 
Articulata, and Vertebrata, but only admits Radiaria as a subprovince on a level 
with Entozoa and Infusoria. Here, the idea of simplicity of structure evidently 
prevails over that of plan, as the subprovinces Radiaria, Entozoa, and Infusoria 
embrace, besides true Radiata, the lowest types of two other branches, Mollusks 
and Articulates. On the other hand, his three subprovinces correspond to the 
first three types of von Siebold; the Infusoria2 of Owen embracing the same 
animals as the Protozoa of Siebold, his Entozoa3 the same as the Vermes, and his 
Radiaria the same as the Zoophyta, with the single exception that Owen refers 
the Annellata to the province of Articulata, whilst Siebold includes them among 
his Vermes. Beyond this the types of Mollusca and Articulata (Arthropoda) of 
the two distinguished anatomists entirely agree. The position assigned by Owen 
to the provinces Articulata and Mollusca, not one above the other, but side by 
side with one another,4 is no doubt meant to express his conviction, that the com- 
plication of structure of these two types does not justify the idea that either 
of them stands higher or lower than the other; and this is perfectly correct. 
Several groups, established by previous writers as families or orders, are here 
admitted as classes. His class Epizoa, which is not to be confounded with that 
established by Nitzsch under the same name, corresponds exactly to the family 
called Lernees by Cuvier. His class Hydrozoa answers to the order Hydroida of 
Johnston, and is identical with the class called Dimorph^a by Ehrenberg. His 
class Cielelmintha corresponds to the order of Intestinaux Cavitaires established 
1 I have given precedence to the classification 
of Owen over those of von Siebold and Stannius, 
Milne-Edwards, Leuckart, etc., because the first edi- 
tion of the " Lectures on Comparative Anatomy " 
was published in 1843; but in estimating its features, 
as expressed in the preceding diagram, it should be 
borne in mind that, in the first edition, the classes 
alone are considered, and that the orders and families 
were only added to the second edition in 1855. I 
mention this simply to prevent the possibility of 
being understood as ascribing to Owen all those sub- 
divisions of the classes, which he admits, and which 
do not appear in the systems considered before his. 
2 The Rhizopoda are considered as a group 
coequal to Rotifera and Polygastria, on p. 16 of 
the " Lectures," but on p. 59, they stand as a sub- 
order of Polygastria. 
8 The Turbellaria are represented as an inde- 
pendent group, on p. 16, and referred as a suborder 
to the Trematoda, on p. 118. 
4 From want of room, I have been compelled, 
in reproducing the classification of Owen in the 
preceding diagram, to place his provinces Articulata 
and Mollusca one below the other upon my page ; 
according to his views, they should stand on a level, 
side by side with one another. 206 
ESSAY ON CLASSIFICATION. 
Part I. 
by Cuvier, with the addition of Gordius; while his class Sterelmintha has the 
same circumscription as the order Intestinaux Parenchymateux of Cuvier. Generally 
speaking, it should not be understood that the secondary divisions mentioned by the 
different authors, whose systems I have analyzed here, were established by them. 
They are frequently borrowed from the results obtained by special investigators of 
isolated classes. But it would lead me too far, to enter here into a discussion 
of all these details. 
This growing resemblance of the modern systems of Zoology is a very favorable 
sign of our times. It would, indeed, be a great mistake to assume, that it is solely 
owing to the influence of different authors upon one another; it is, on the con- 
trary, to a very great extent, the result of our better acquaintance with Nature. 
When investigators, at all conversant with the present state of our science, must 
possess nearly the same amount of knowledge, it is self-evident that their views 
can no longer differ so widely as they did when each was familiar only with 
a part of the subject. A deeper insight into the animal kingdom must, in the 
end, lead to the conviction that it is not the task of zoologists to introduce order 
among animals, but that their highest aim should be simply to read the natural 
affinities which exist among them, so that the more nearly our knowledge embraces 
the whole field of investigation, the more closely will our opinions coincide. 
As to the value of the classes adopted by Owen, I may further remark that 
recent investigations, of which he might have availed himself, have shown that the 
Cirripedia and his Epizoa are genuine Crustacea, and that the Entozoa can no 
longer be so widely separated from the Annellata as in his system. With reference 
to the other classes, I refer the reader to my criticism of older systems, and to 
the first section of this Chapter. 
It is a great satisfaction for me to find that the views I have advocated in 
the preceding sections, respecting the natural relations of the leading groups of 
the animal kingdom, coincide so closely with the classification of that distinguished 
zoologist, Milne-Edwards, lately presented by him as the expression of his present 
views of the natural affinities of animals. He is the only original investigator 
who has recently given his unqualified approbation to the primary divisions first 
proposed by Cuvier, admitting, of course, the rectifications among the group of 
secondary rank, rendered necessary by the progress of science, to which he has 
himself so largely contributed. 
As to the classes adopted by Milne-Edwards, I have little to add to what I 
have already stated before, with reference to other classifications. Though no 
longer overruling the idea of plan, that of complication of structure has still too 
much influence with Milne-Edwards, inasmuch as it leads him to consider as classes, 
groups of animals which differ only in degree, and are therefore only orders. Chap. III. 
ANATOMICAL SYSTEMS. 
207 
Such are, no doubt, his classes of Molluscoids and those of Worms, besides the 
Myriapods and Arachnids. Respecting the Fishes, I refer to my remarks in the 
first section (p. 187) of this Chapter. 
CLASSIFICATION OF MILNE-EDWARDS. 
The following diagram is drawn from the author's Cours elementaire d'Histoire naturelie, Paris, 1855, 
1 vol. 12mo., 7th edit., in which he has presented the results of his latest investigations upon the classifica- 
tion of the Vertebrata and Articulata; the minor subdivisions of the Worms, Mollusks, and Zoophytes, 
however, are not considered in this work.1 
I. Osteozoaria, or Vertebrata. 
Subbranch. Allantoidians. 
Cl. Mammalia. 1°. Monodelphya. a. Propria. Ord. Bimana, 
Quadrumana, Cheiroptera, Insectivora, Rodentia, Edentata, Carni- 
vora, Amphibia, Pachydermata, Ruminantia. b. Pisciformia. Ord. 
Cetacea. 2°. Didelphya. Ord. Marsupialia, Monotremata. 
Cl. Birds. Ord. Rapaces, Passeres, Scansores, Gallin®, 
Grail®, and Palmipedes. 
Cl. Reptiles. Ord. Chelonia, Sauria, Ophidia. 
Subbranch. An all ant oi di an s. 
Cl. Batrachians. Ord. Anura, 
Urodela, Perennibranchia, C®cili®. 
Cl. Fishes. 1°. Ossei. Ord. Acan- 
thopterygii, Abdominales, Subbrachii, 
Apodes, Lophobranchii, and Plectog- 
nathi. 2°. Chondropterygii. Ord. Stu- 
riones, Selachii, and Cyclostomi. 
II. Entomozoa, or Annellata 
Subbranch. Arthropoda. 
Cl. I n s e c t a. Ord. Coleoptera, Orthoptera, Nevroptera, Hymenoptera, 
Lepidoptera, Hemiptera, Diptera, Rhipiptera, Anoplura, and Thysanura. 
Cl. Myriapoda. Ord. Chilognatha and Chilopoda. 
Cl. Arachnids. Ord. Pulmonaria and Trachearia. 
Cl. Crustacea. 1°. Podophthalmia. Ord. Decapoda and Stomapoda. 
2°. Edriophthalma. Ord. Amphipoda, L®modipoda, and Isopoda. 3°. Bran- 
chiopoda. Ord. Ostrapoda, Phyllopoda, and Trilobit®. 4°. Entomostraca. Ord. 
Copepoda, Cladocera, Siphonostoma, Lern®ida, Cirripedia. 5°. Xiphosura. 
Subbranch. Vermes. 
Cl. Annelids. 
Cl. Helminths. 
Cl. Turbellaria. 
Cl. Cestoidea. 
Cl. Rotatoria. 
HI. Malacozoaria, or Mollusca. 
Subbranch. Mollusks proper. 
Cl. Cephalopods. 
Cl. Pteropods. 
Cl. Gasteropods. 
Cl. Acephala. 
Subbranch. Mo lluscoids 
Cl. T u n i c a t a. 
Cl. B r y o z o a. 
IV. Zoophytes. 
Subbranch. R a di ar i a, or R a di at a 
Cl. Echinoderms. 
Cl. Ac alephs. 
Cl. Corallaria, or Polypi. 
Subbranch. Sarcodaria. 
Cl. Infusoria. 
Cl. Spongiaria. 
1 Consult, for these, his recent papers upon Polyps, Mollusks, and Crustacea, in the Ann. des Sc. Nat. 208 
ESSAY ON CLASSIFICATION. 
Part I 
CLASSIFICATION OF VON SIEBOLD AND STANNIUS. 
This classification is adopted in the following work: Siebold, (C. Th. v.,) and Stannius, (II.,) Lehrbuch 
der vergleichenden Anatomie, Berlin, 1845, 2 vols. 8vo. A second edition is now in press. 
EVERTEBRATA. 
I. Protozoa 
Cl. 1. Infusoria. Ord. Astoma and Stomatoda. 
Cl. 2. R h i z o p o d a. Ord. Monosomatia and Polysomatia. 
II. ZOOI'HYTA. 
Cl. 3. Polypi. Ord. Anthozoa and Bryozoa. 
Cl. 4. Acalephae. Ord. Siphonophora, Discophora, Ctenophora. 
Cl. 5. E chinode rm ata. Ord. Crinoidea, Asteroidea, Echinoidea, Holothurioidea, and 
Sipunculoidea. 
III. Vermes. 
Cl. 6. II e 1 m in t h e s. Ord. Cystici, Ces- 
todes, Trematodes, Acanthocephali, 
Gordiacei, Nematodes. 
Since the publication of the work quoted above, Sie- 
bold has introduced most important improvements in the 
classification of the Worms, and greatly increased our 
knowledge of these animals. 
Cl. 7. Turbellarii. Ord. Rhabdococli, Dendrocoeli. 
Cl. 8. R o t a t o r i i. Not subdivided into orders. 
Cl. 9. Annulati. Ord. Apodes and Chaetopodes. 
IV. Mollusca. 
Cl. 10. Acephala. Ord. Tunicata, Brachiopoda, Lamellibranchia. 
Cl. 11. Cephalophora, Meek., (Gasteropoda.) Ord. Pteropoda, Ileteropoda, Gasteropoda, 
Cl. 12. Cephalopoda. Not subdivided into orders. 
V. Arthropoda. 
Cl. 13. Crustacea. Ord. Cirripedia, Siphonostoma, Lophyropoda, Phyllopoda, Poecilopoda. 
Laemodipoda, Isopoda, Amphipoda, Stomapoda, Decapoda, Myriapoda. 
Cl. 14. A r a c h n i d a . Orders without names. 
Cl. 15. Insecta. a. Ametabola. Ord. Aptera. b. Hemimetabola; Ord. He- 
miptera, Orthoptera. c. II o 1 o in e t a b o 1 a . Ord. Diptera, Lepidoptera, Hymenop- 
tera, Strepsiptera, Nevroptera, and Coleoptera. 
VERTEBRATA. 
VI. Vertebrata. 
Cl. 1G. Pisces. Subclasses: 1st. Leptocardii. 2d. Marsipobran chii. 3d. 
E 1 a s m o b r a n c h i i; Ord. Holocephali, Plagiostomi. 4th. G a n o i d e i; Ord. 
Chrondrostei, Ilolostei. 5th. Teleostei; Ord. Acanthopteri, Anacanthini, Pharyn- 
gognathi, Physostomi, Plectognathi, Lophobranchii. 6th. Dipnoi. 
Cl. 17. Reptilia. Subclasses: 1st. Dipnoa; Ord. Urodela, Batrachia, Gymnophiona. 
2d. Mo n o p noa : a. Streptostylica ; Ord. Ophidia, Sauria. b. Monimostylica; Ord. 
Chelonia, Crocodila. 
Cl. 18. Aves. 
Cl. 19. Mammalia. 
The subdivisions of the classes Pisces and Reptilia are taken from the sec- 
ond edition, published in 1854-1856, in which J. Muller's arrangement of the 
Fishes is adopted; that of the Reptiles is partly Stannius's own. The 
classes Aves and Mammalia, and the first volume of the second edition, are 
not yet out. Chap. III. 
ANATOMICAL SYSTEMS. 
209 
The most original feature of the classification of von Siebold is the adoption 
of the types Protozoa and Vermes, in the sense in which they are limited here. 
The type of Worms has grown out of the investigations of the helminthologists, 
who, too exclusively engaged with the parasitic Worms, have overlooked their rela- 
tions to the other Artic ulata. On the other hand, the isolation in which most ento- 
mologists have remained from the zoologists in general, has no doubt had its share in 
preventing an earlier thorough comparison of the Worms and the larval conditions of 
Insects, without which the identity of type of the Worms, Crustacea, and Insects 
can hardly be correctly appreciated. Concerning the classes1 adopted by von Sie- 
bold and Stannius, I have nothing to remark that has not been said already. 
CLASSIFICATION OF R. LEUCKART. 
The classification of Leuckart is compiled from the following work: Leuckart, (R.,) Ueber die Mor- 
phologic und die Verwandtschaftsverhaltnisse der wirbellosen Thiere, Braunschweig, 1848, 1 vol. 8vo. 
I. Coelenterata, Lkt. 
Cl. 1. Polypi. Ord. Anthozoa and Cylicozoa (Lucernaria.) 
Cl. 2. Acalephae. Ord. Discophorae and Ctenophorae. 
II. Echinodermata, Lkt. 
Cl. 3. Pelmatozoa, Lkt. Ord. Cystidea and Crinoidea. 
Cl. 4. Actinozoa, Latr. Ord. Echinida and Asterida. 
Cl. 5. Scytodermata, Brmst. Ord. Holothuriae and Sipunculida. 
III. Vermes. 
Cl. 6. Anenterati, Lkt. Ord. Cestodes and Acanthocephali. (Helminthes, Burnt.) 
Cl. 7. Apo des, Lkt. Ord. Nemertini, Turbellarii, Trematodes, and Hirudinei. (Trematodes, Burnt.) 
Cl. 8. C i 1 i a t i, Lkt. Ord. Bryozoa and Rotiferi. 
Cl. 9. Annelides. Ord. Nematodes, Lumbricini, and Branchiati. (Annulati, Burnt., excl. Ne- 
mertinis et Hirudineis.) 
IV. Arthropoda. 
Cl. 10. Crustacea. Ord. Entomostraca (Neusticopoda Car.) and Malacostraca. 
Cl. 11. Insecta. Ord. Myriapoda, Arachnida, (Acera, Latr.,) and Ilexapoda. 
V. Mollusca, Cuv. (Palliata, Nitzsch.) 
Cl. 12. Tunicata. Ord. Ascidia; (Tethyes 
Sav.) and Salpae (Thalides Sav.) 
Leuckart is somewhat inclined to consider the Tunicata 
>■ not simply as a class, but even as another great type or branch, 
intermediate between Echinoderms and Worms. 
Cl. 13. Acephala. Ord. Lamellibranchiata (Cormopoda Nitzsch, Pelecypoda Car.) and Bra- 
chiopoda. 
Cl. 14. Gasteropoda. Ord. Heterobranchia, (Pteropoda, Inferobranchia, and Tectibranchia,) 
Dermatobranchia, (Gymnobranchia and Phlebenterata,) Heteropoda, Ctenobranchia, Pulmo- 
nata, and Cyclobranchia. 
Cl. 15. Cephalopoda. 
VI. Vertebrata. (Not considered.) 
1 The names of the types, Protozoa and Vermes, are older 
than their limitation in the classification of Siebold. That of 
Protozoa, first introduced by Goldfuss, has been used in vari- 
ous ways for nearly half a century, while that of Worms was first 
adopted by Linnaeus, as a great division of the animal king- 
dom, but in a totally different sense. 210 
ESSAY ON CLASSIFICATION. 
Part I. 
I need not repeat here what I have already stated, in the first section, respecting 
the primary divisions adopted by Siebold and Leuckart. As to the classes, I may 
add that his three classes of Echinoderms exhibit only ordinal characters. Besides 
Birds and Cephalopods, there is not another class so well defined, and so little 
susceptible of being subdivided into minor divisions presenting any thing like class 
characters, as that of Echinoderms. Their systems of organs are so closely homo- 
logical, (compare p. 183,) that the attempt here made by Leuckart, of subdividing 
them into three classes, can readily be shown to rest only upon the admission, as 
classes, of groups which exhibit only ordinal characters, namely, different degrees of 
complication of structure. With reference to the classes of Worms, the same is 
equally true, as shown above. The arrangement of these animals proposed by Bur- 
meister is certainly more correct than those of von Siebold and of Leuckart, inas- 
much as he refers already correctly the Rotifera to the class of Crustacea, and does 
not, like Leuckart, associate the Bryozoa with the Worms. 1 agree, however, with 
Leuckart respecting the propriety of removing the Nemertini and Hirudinei from 
among the true Annelides. Again, Burmeister appreciates also more correctly the 
position of the whole type of Worms, in referring them, with de Blainville, to the 
branch of Articulata. 
The common fault of all the anatomical classifications which have been proposed 
since Cuvier consists, first, in having given up, to a greater or less extent, the funda- 
mental idea of the plan of structure, so beautifully brought forward by Cuvier, and 
upon which he has insisted with increased confidence and more and more distinct con- 
sciousness, ever since 1812; and, second, in having allowed that of complication of 
structure frequently to take the precedence over the more general features of plan, 
which, to be correctly appreciated, require, it is true, a deeper insight into the struc- 
ture of the whole animal kingdom than is needed merely for the investigation of 
anatomical characters in single types. 
Yet, if we take a retrospective glance at these systems, and especially con- 
sider the most recent ones, it must be apparent to those who are conversant with 
the views now obtaining in our science, that, after a test of half a century, the 
idea of the existence of branches, characterized by different plans of structure, as 
expressing the true relations among animals, has prevailed over the idea of a 
gradated scale including all animals in one progressive series. When it is con- 
sidered that this has taken place amidst the most conflicting views respecting classi- 
fication, and even in the absence of any ruling principle, it must be acknowl- 
edged that this can be only owing to the internal truth of the views first pro- 
pounded by Cuvier. We recognize in the classifications of Siebold, Leuckart, and 
others the triumph of the great conception of the French naturalist, even though 
their systems differ greatly from his, for the question whether there are four or Chap. III. 
PHYSIOPHILOSOPHICAL SYSTEMS. 
211 
more great plans, limited in this or any other way, is not a question of prin- 
ciple, but one involving only accuracy and penetration in the investigation; and 
I maintain that the first sketch of Cuvier, with all its imperfections of details, pre- 
sents a picture of the essential relations existing among animals truer to nature 
than the seemingly more correct classifications of recent writers. 
SECTION V. 
PHYSIOPHILOSOPHICAL SYSTEMS. 
About the time that Cuvier and the French naturalists were tracing the structure 
of the animal kingdom, and attempting to erect a natural system of Zoology upon 
this foundation, there arose in Germany a school of philosophy, under the lead 
of Schelling, which extended its powerful influence to all the departments of physical 
science. Oken, Kieser, Bojanus, Spix, Huschke, and Carns are the most eminent 
naturalists who applied the new philosophy to the study of Zoology. But no 
one identified his philosophical views so completely with his studies in natural 
history as Oken. 
Now that the current is setting so strongly against every thing which recalls 
the German physiophilosophers and their doings, and it has become fashionable 
to speak ill of them, it is an imperative duty for the impartial reviewer of the 
history of science to show how great and how beneficial the influence of Oken 
has been upon the progress of science in general and of Zoology in particular. 
It is moreover easier, while borrowing his ideas, to sneer at his style and his 
nomenclature, than to discover the true meaning of what is left unexplained in 
his mostly paradoxical, sententious, or aphoristical expressions; but the man who 
has changed the whole method of illustrating comparative Osteology, - who has 
carefully investigated the embryology of the higher animals, at a time when few 
physiologists were paying any attention to the subject, who has classified the three 
kingdoms of nature upon principles wholly his own, who has perceived thousands 
of homologies and analogies among organized beings entirely overlooked before, who 
has published an extensive, treatise of natural history containing a condensed account 
of all that was known at the time of its publication, who has conducted for twenty- 
five years the most extensive and most complete periodical review of the natural 
sciences ever published, in which every discovery made during a quarter of a 
century is faithfully recorded, the man who inspired every student with an ardent 
love for science, and with admiration for his teacher, - that man will never be 
forgotten, nor can the services he has rendered to science be overlooked, so long 
as thinking is connected with investigation. 212 
ESSAY ON CLASSIFICATION. 
Part I. 
CLASSIFICATION OF OKEN. 
The following diagram of Oken's classification is compiled from his Allgemeine Naturgeschichte fur alle 
Stande, Stuttgardt, 1833-1842, 14 vols. 8vo.; vol. 1, p. 5. The changes this system has undergone may 
be ascertained by comparing his Lehrbuch der Naturphilosophie, lena, 1809-1811, 3 vols. 8vo.; 2d edit., 
Jena, 1831; 3d edit., Zurich, 1843; Engl. Ray Society, London, 1847, 1 vol. 8vo.- Lehrbuch der Natur- 
geschichte, Leipzig, 1813; Weimar, 1815 and 1825, 8vo.- Handbuch der Naturgeschichte zum Gebrauch 
bei Vorlesungen, Nurnberg, 181G-1820, 8vo. - Naturgeschichte fur Schulen, Leipzig, 1820, 1 vol. 8vo., 
and various papers in the Isis. 
1st Grade. Intestinal Animals ; also called 7?oc^-animals and 7V>wcA-animals. Only one cavity ; no head 
with a brain, only the lowest sense perfect, intestines and skin organs, but no flesh, that is 
no bones, muscles, or nervous marrow = Invertebrata. 
Characterized by the development of the vegetative systems of organs, which are those of digestion, circula- 
tion, and respiration. Hence - 
Cycle I. Digestive Animals. = Radiata. Essential character: no development beyond an intestine. 
Cl. 1. Infusoria, (Stomach animals.) Mouth with cilia only, to vibrate. 
Cl. 2. Polypi, (Intestine animals.) Mouth with lips and tentacles, to seize. 
Cl. 3. Acalephae, (Lacteal animals.) Body traversed by tubes similar to the lymphatic vessels. 
Cycle II. Circulative Animals. = Mollusks. Essential character: intestine and vessels. 
Cl. 4. Acephala, (Biauriculate animals.) Membranous heart with two auricles. 
Cl. 5. Gasteropoda, (Uniauriculate animals.) Membranous heart with one auricle. 
Cl. 6. Cephalopoda, (Bicardial animals.) Two hearts. 
Cycle III. Respirative Animals. = Articulata. Essential character: intestine, vessels, and spiracles. 
Cl. 7. Worms, (Skin animals.) Respire with the skin itself, or part of it, no articulated feet. 
Cl. 8. Crustacea, (Branchial animals.) Gills or air tubes arising from the horny skin. 
Cl. 9. Insects, (Tracheal animals.) Tracheae internally, gills externally as wings. 
» 
2d Grade. Flesh Animals; also called T&atZ-animals. = Vertebrata. Two cavities of the body, surrounded 
by fleshy walls, (bones and muscles,) inclosing nervous marrow and intestines. Head with 
brain; higher senses developed. Characterized by the development of the animal systems, 
namely, the skeleton, the muscles, the nerves, and the senses. 
Cycle IV. Carnal Animals proper. Senses not perfected. 
Cl. 10. Fishes, (^one-animals.) Skeleton predominating, very much broken up; muscles white, 
brain without gyri, tongue without bone, nose not perforated, ear concealed, eyes without 
lids. 
Cl. 11. Reptiles, (JfuscZe-animals.) Muscles red, brain without convolutions, nose perforated, 
ear without external orifice, eyes immovable with imperfect lids. 
Cl. 12. Birds, (Aerve-animals.) Brain with convolutions, ears open, eyes immovable, lids 
imperfect. 
Cycle V. Sensual Animals. All anatomical systems, and the senses perfected. 
Cl. 13. Mammalia, (Nense-animals.) Tongue and nose fleshy, ears open, mostly with a conch, 
eyes movable, with two distinct lids. Chap. III. 
PHYSIOPHILOSOPHICAL SYSTEMS. 
213 
The principles laid down by Oken, of which this classification is the practical 
result for Zoology, may be summed up in the following manner: The grades or 
great types of Animals are determined by their anatomical systems, such as the 
body and head; or the intestines, and the flesh and senses. Hence two grades 
in the animal kingdom. Animals are, as it were, the dismembered body of man 
made alive. The classes of animals are the special representation in living forms 
of the anatomical systems of the highest being in creation. 
Man is considered, in this system, not only as the key of the whole animal 
kingdom, but also as the standard measure of the organization of animals. There 
exists nothing in the animal kingdom which is not represented in higher combina- 
tions in Man. The existence of several distinct plans of structure among animals is 
virtually denied. They are all built after the pattern of Man; the differences 
among them consist only in their exhibiting either one system only, or a larger 
or smaller number of systems of organs of higher or lower physiological impor- 
tance, developed either singly, or in connection with one another, in their body. 
The principles of classification of both Cuvier and Ehrenberg are here entirely 
negatived. The principle of Cuvier, who admits four different plans of structure 
in the animal kingdom, is, indeed, incompatible with the idea that all animals 
represent only the organs of Man. The principle of Ehrenberg, who considers 
all animals as equally perfect, is as completely irreconcilable with the assumption 
that all animals represent an unequal sum of organs; for, according to Oken, the 
body of animals is, as it were, the analyzed body of Man, the organs of which 
live singly, or in various combinations as independent animals. Each such com- 
bination constitutes a distinct class. The principle upon which the orders are 
founded has already been explained above, (Chap. II., Sect. III., p. 154.) 
There is something very taking in the idea that Man is the standard of appre- 
ciation of all animal structures. But all the attempts which have thus far been 
made to apply it to the animal kingdom as it exists, must be considered as com- 
plete failures. In his different works, Oken has successively identified the systems 
of organs of Man with different groups of animals, and different authors, who 
have adopted the same principle of classification, have identified them in still differ- 
ent ways. The impracticability of such a scheme must be obvious to any one 
who has satisfied himself practically of the existence of different plans of structure 
in the organization of animals. Yet, the unsoundness of the general principle of 
the classifications of the physiophilosophers should not render us blind to all that 
is valuable in their special writings. The works of Oken in particular teem with 
original suggestions respecting the natural affinities of animals; and his thorough 
acquaintance with every investigation of his predecessors and contemporaries shows 
him to have been one of the most learned zoologists of this century. 214 
ESSAY ON CLASSIFICATION. 
Part I. 
CLASSIFICATION OF FITZINGER. 
This diagram is extracted from Fitzinger's Systema Reptilium, Vindobonae, 1843, 1 vol. 8vo. 
I. Provincia. Evertebrata. 
Animalia systematum anatomicorum vegetativorum gradum evolutionis exhibentia. 
A. Gradus evolutionis systematum physiologicorum vegetativorum. 
I. Circulus. Gastrozoa. 
Evolutio systematis nutritionis. 
a. Evolutio praevalens 
systematis digestionis. 
Cl. 1. Infusoria. 
b. Evolutio praevalens 
systematis circulationis. 
Cl. 2. Z o o p h y t a. 
c. Evolutio praevalens 
systematis respirationis. 
Cl. 3. A c a 1 e p h a e. 
II. Circulus. Physiozoa. 
Evolutio systematis generationis. 
Cl. 4. Vermes. 
Cl. 5. Radi at a. 
Cl. 6. Annulata. 
B. Gradus evolutionis systematum physiologicorum animalium. 
III. Circulus. Dermatozoa. 
Evolutio systematis sensibilitatis. 
Cl. 7. A c e p h a 1 a. 
Cl. 8. Cephalopoda. 
Cl. 9. Mollusca. 
IV. Circulus. Artiirozoa. 
Evolutio systematis motus. 
Cl. 10. Crustacea. 
Cl. 11. Araehnoidea. 
Cl. 12. Insecta. 
II. Provincia. Vertebrata. 
Animalia systematum anatomicorum animalium gradum evolutionis exhibentia. 
A. Gradus evolutionis systematum physiologicorum vegetativorum. 
a. Evolutio systematis nutritionis, simulque ossium: . . Cl. 13. Pisces. 
6. Evolutio systematis generationis, simulque musculorum: Cl. 14. Reptilia. 
B. Gradus evolutionis systematum physiologicorum animalium. 
c. Evolutio systematis sensibilitatis, simulque nervorum: Cl. 15. Aves. 
d. Evolutio systematis motus, simulque sensuum : . . . Cl. 16. M a m m a 1 i a . 
The fundamental idea of the classification of Fitzinger is the same as that 
upon which Oken has based his system. The higher divisions, called by him 
provinces, grades, and cycles, as well as the classes and orders, are considered as 
representing either some combination of different systems of organs, or some par- 
ticular system of organs, or some special organ. His two highest groups (provinces) 
are the Evertebrata and Vertebrata. The Evertebrata represent the systems of 
the vegetative organs, and the Vertebrata those of the animal organs, as the Gut- Chap. III. 
PHYSIOPIIILOSOPHICAL SYSTEMS. 
215 
animals and the Flesh-animals of Oken. Instead, however, of adopting, like Oken, 
anatomical names for his divisions, Fitzinger employs those most generally in use. 
His subdivisions or grades of these two primary groups are based upon a repetition 
of the same differences, within their respective limits. The Invertebrata, in which 
the vegetative organs prevail, are contrasted with those in which the animal organs 
prevail, and the same distinction is again drawn among the Vertebrata. Each of 
these embraces two circles founded upon the development of one particular system 
of organs, etc. It cannot be expected that the systems founded upon such principles 
should present a closer agreement with one another than those which are based 
upon anatomical differences; yet I would ask, what becomes of the principle itself, 
if its advocates cannot even agree upon what anatomical systems of organs their 
classes are founded ? According to Oken, the Mollusks (Acephala, Gasteropoda, and 
Cephalopoda) represent the system of circulation, at least in the last edition of 
his system he views them in that light, whilst Fitzinger considers them as repre- 
senting the system of sensibility. Oken identifies the Articulata (Worms, Crustacea, 
and Insects) with the system of respiration, Fitzinger with that of motion, with 
the exception of the Worms, including Radiata, which he parallelizes with the 
system of reproduction, etc. Such discrepancies must shake all confidence in 
these systems, though they should not prevent us from noticing the happy com- 
parisons and suggestions, to which the various attempts to classify the animal king- 
dom in this way have led their authors. It is almost superfluous to add, that, 
great as the disagreement is between the systems of different physiophilosophers, 
we find quite as striking discrepancies between the different editions of the system 
of the same author. 
The principle of the subdivision of the classes among Invertebrata is here exemplified from the Radiata, 
(Echinodermata.) Each series contains three orders. 
1st Series. 
Evolutio praevalens 
systematis digestionis. 
Asteroidea. 
1. Encrinoidea. 2. Comatulina. 
3. Asterina. 
2d Series. 
Evolutio praevalens 
systematis circulationis. 
Echinodea. 
1. Aprocta. 2. Echinina. 
3. Spatangoidea. 
3d Series. 
Evolutio praevalens 
systematis respirationis. 
Scytodermata (Holothurioids.) 
1. Synaptoidea. 2. Holothurioidea. 
3. Pentactoidea. 
In Vertebrata, each class has five series and each series three orders; so in Mammalia, for example: - 
1st Series. 2d Series. 3d Series. 4th Series. 5th Series. 
Evolutio praevalens Evolutio praevalens Evolutio praevalens Evolutio praevalens Evolutio praevalens 
sensus tactus. sensus gustus. sensus olfactus. sensus auditus. sensus visas. 
Cetacea. 
1. Balanodea. 
2. Delphinodea. 
3. Sirenia. 
Pachydermata. 
1. Phocina. 
2. Obesa. 
3. Ruminantia. 
Edentata. 
1. Monotremata. 
2. Lipodonta. 
3. Tardigrada. 
Unguiculata. 
1. Glires. 
2. Bruta. 
3. Feras. 
Primates. 
1. Chiropteri. 
2. Hemipitheci. 
3. Anthropomorphi. 216 
ESSAY ON CLASSIFICATION. 
Part I. 
Instead of considering the orders as founded upon a repetition of the characters 
of higher groups, as Oken would have it, Fitzinger adopts series, as founded upon 
that idea, and subdivides them further into orders, as above. These series, however, 
have still less reference to the systems of organs, which they are said to represent, 
than either the classes or the higher divisions of the animal kingdom. In these 
attempts to arrange minor groups of animals into natural series, no one can fail 
to perceive an effort to adapt the frames of our systems to the impression we 
receive from a careful examination of the natural relations of organized beings. 
Everywhere we notice such series; sometimes extending only over groups of species, 
at other times embracing many genera, entire families, nay, extending frequently to 
several families. Even the classes of the same branch may exhibit more or less 
distinctly such a serial gradation. But I have failed, thus far, to discover the 
principle to which such relations may be referred, as far as they do not rest upon 
complication of structure,1 or upon the degree of superiority or inferiority of the 
features upon which the different kinds of groups are themselves founded. Analogy 
plays also into the series, but before the categories of analogy have been as 
carefully scrutinized as those of affinity, it is impossible to say within what limits 
this takes place. 
CLASSIFICATION OF McLEAY. 
The great merit of the system of McLeay,2 and in my opinion it has no other 
claim to our consideration, consists in having called prominently the attention of 
naturalists to the difference between two kinds of relationship, almost universally 
confounded before: affinity and analogy. Analogy is shown to consist in the repeti- 
tion of similar features in groups otherwise remote, as far as their anatomical 
characters are concerned, whilst affinity is based upon similarity in the structural 
relations. On account of the similarity of their locomotion, Bats, for instance, may 
be considered as analogous to Birds; Whales are analogous to Fishes on account 
of the similarity of their form and their aquatic mode of life; whilst both Bats 
and Whales are allied to one another and to other Mammalia on account of the 
identity of the most characteristic features of their structure. This important dis- 
tinction cannot fail to lead to interesting results. Thus far, however, it has only 
produced fanciful comparisons from those who first traced it out. It is assumed, 
for instance, by McLeay, that all animals of one group must be analogous to 
1 Compare Chap. II., Sect. 3, p. 153. 
2 I have introduced the classification of McLeay 
in this section, not because of any resemblance to 
those of the German physiophilosophers, but on 
account of its general character, and because it is 
based upon an ideal view of the affinities of animals. Chap. III. 
PHYSIOPHILOSOPHICAL SYSTEMS. 
217 
those of every other group, besides forming a circle in themselves; and in order 
to carry out this idea, all animals are arranged in circular groups, in such a manner 
as to bring out these analogies, whilst the most obvious affinities are set aside to 
favor a preconceived view. But that I may not appear to underrate the merits 
of this system, I will present it in the very words of its most zealous admirer 
and self-complacent expounder, the learned William Swainson.1 
" The Horae Entomologies,2 unluckily for students, can only be thoroughly 
understood by the adept, since the results and observations are explained in different 
parts; the style is somewhat desultory, and the groups, for the most part, are rather 
indicated than defined. The whole, in short, is what it professes to be, more a 
rough sketch of the leading peculiarities of the great divisions of animals, and the 
manner in which they are probably connected, than an accurate determination of 
the groups themselves, or a demonstration of their real affinities. More than this, 
perhaps, could not have been expected, considering the then state of science, and 
the herculean difficulties which the author had to surmount. The work in ques- 
tion has now become exceedingly scarce, and this will be an additional reason 
with us for communicating occasional extracts from it to the reader. Mr. McLeay's 
theory will be best understood by consulting his diagram; for he has not, as we 
have already remarked, defined any of the vertebrated groups. Condensing, how- 
ever, the result of his remarks, we shall state them as resolvable into the following 
propositions: 1. That the natural series of animals is continuous, forming, as it 
were, a circle, so that, upon commencing at any one given point, and thence 
tracing all the modifications of structure, we shall be imperceptibly led, after passing 
through numerous forms, again to the point from which we started; 2. That no 
groups are natural which do not exhibit such a circular series; 3. That the 
primary divisions of every large group are ten, five of which are composed of 
comparatively large circles, and five of smaller: these latter being termed osculant, 
and being intermediate between the former, which they serve to connect; 4. That 
there is a tendency in such groups as are placed at the opposite points of a 
circle of affinity ' to meet each other; ' 5. That one of the five larger groups 
into which every natural circle is divided, 'bears a resemblance to all the rest, or, 
more strictly speaking, consists of types which represent those of each of the four 
other groups, together with a type peculiar to itself.' These are the chief and 
leading principles which Mr. McLeay considers as belonging to the natural system. 
We shall now copy his diagram, or table of the animal kingdom, and then endeavor, 
with this help, to explain the system more in detail." 
1 Swainson, (W.,) A Treatise of the Geography 
and Classification of Animals, London, 1835, 1 vol. 
12mo., p. 201-205. 
2 McLeay, (W. S.,) Horae Entomologicae, or 
Essays on the Annulose Animals, London, 1819-21, 
2 vols. 8vo. 218 
ESSAY ON CLASSIFICATION. 
Part I. 
Least organized 
Beings of the Vegetable Kingdom. 
MOLLUSCA. 
Pteropoda. 
Acephala. 
v Brachiopoda. J 
Rudes. > 
/ P. Vaginati. 
/ ACRITA. 
P Agastria. 
\ P. Natantes. 
\ Intestina. / 
Reptilia. % \ 
Aves. \ 
fERTEBRATA. \ 
Mammalia. / 
iphibia. / 
Pisces. / 
AN! MALIA 
Fistulida. 
/ Acalephid®. 
RADIATA. 
Echinid®. 
\ Medusid®. 
\ Stellerid®. / 
Ametabola. 
/ Mandibulata. ' 
ANNULOSA. 
Crustacea. 
v Ilaustellata. / 
\ Arachnid®. / 
"We must, in the first instance, look to the above tabular disposition of all 
animals, as forming themselves collectively into one great circle, which circle touches 
or blends into another, composed of plants, by means of the ' least organized beings 
of the vegetable kingdom.' Next we are to look to the larger component parts 
of this great circular assemblage. We find it, in accordance with the third proposi- 
tion, to exhibit five great circles, composed of the Mollusca, or shellfish ; Acrita, 
or polyps; Radiata, or star-fish; Annulosa, or insects; and Vertebrata, or verte- 
brated animals; each passing or blending into each other, by means of five other 
groups of animals, much smaller, indeed, in their extent, but forming so many 
connecting or osculant circles.1 The number, therefore, as many erroneously suppose, 
is not five, but ten. This is quite obvious; and our opinion on this point is 
confirmed by the author himself, in the following passage, when alluding to his 
remarks upon the whole: - 'The foregoing observations, I am well aware, are far 
from accurate, but they are sufficient to prove that there are five great circular 
groups in the animal kingdom, each of which possesses a peculiar structure; and that 
1 In the original diagram, as in that above, these 
five smaller circles are not represented graphically, 
but merely indicated by the names arranged like 
rays between the five large circles. 219 
Chap. III. 
PHYSIOPHILOSOPHICAL SYSTEMS. 
these, when connected by means of five smaller osculant groups, compose the 
whole province of Zoology.' Now these smaller osculant groups are to be viewed 
as circles, for, as it is elsewhere stated, 4 every natural group is a circle, more 
or less complete.' This, in fact, is the third general principle of Mr. McLeay's 
system, and he has exemplified his meaning of a natural group in the above 
diagram, where all animals are arranged under five large groups or circles, and 
five smaller ones. Let us take one of these groups, the Vertebrata: does that 
form a circle of itself? Yes; because it is intimated that the Reptiles {Reptilia) 
pass into the Birds, {Aves,) these again into the Quadrupeds, {Mammalia,) Quadrupeds 
unite with the Fishes, {Pisces,) these latter with the amphibious Reptiles, and the 
Frogs bring us back again to the Reptiles, the point from whence we started. 
Thus, the series of the vertebrated group is marked out and shown to be circular; 
therefore, it is a natural group. This is an instance where the circular series 
can be traced. We now turn to one where the series is imperfect, but where 
there is a decided tendency to a circle: this is the Mollusca. Upon this group 
our author says, 41 have by no means determined the circular disposition to hold 
good among the Mollusca; still, as it is equally certain that this group of animals 
is as yet the least known, it may be improper, at present, to conclude that it 
forms any exception to the rule; it would even seem unquestionable that the 
Gasteropoda of Cuvier return into themselves, so as to form a circular group; but 
whether the Acephala form one or two such, is by no means accurately ascertained, 
though enough is known of the Mollusca to incline us to suspect that they are 
no less subjected, in general, to a circular disposition than the four other great 
groups.' This, therefore, our author considers as one of those groups which, without 
actually forming a circle, yet evinces a disposition to do so; and it is therefore 
presumed to be a natural group. But, to illustrate this principle farther, let us 
return to the circle of Vertebrata. This, as we see by the diagram, contains five 
minor groups, or circles, each of which is again resolvable into five others, regu- 
lated precisely in the same way. The class Aves, for example, is first divided 
into rapacious birds, {Raptores,) perching birds, {Insessores,) gallinaceous birds, {Rasores,) 
wading birds, {Grallatores,) and swimming birds {Natatores); and the proof of this 
class being a natural group is, in all these divisions blending into each other at 
their confines, and forming a circle. In this manner we proceed, beginning with 
the higher groups, and descending to the lower, until at length we descend to 
genera, properly so called, and reach, at last, the species; every group, whether 
large or small, forming a circle of its own. Thus there are circles within circles, 
4 wheels within wheels,' - an infinite number of complicated relations; but all 
regulated by one simple and uniform principle, - that is, the circularity of every 
group." 220 
ESSAY ON CLASSIFICATION. 
Part I. 
The writer who can see that the Quadrupeds unite with the Fishes, and the 
like, and yet says that Cuvier "was totally unacquainted with the very first princi- 
ples of the natural system," hardly deserves to be studied in our days. 
The attempt at representing graphically the complicated relations which exist 
among animals has, however, had one good result; it has checked, more and more, 
the confidence in the uniserial arrangement of animals, and led to the construction 
of many valuable maps exhibiting the multifarious relations which natural groups, 
of any rank, bear to one another. 
SECTION VI. 
EMBRYOLOGICAL SYSTEMS. 
Embryology, in the form it has assumed within the last fifty years, is as 
completely a German science as the " Naturphilosophie." It awoke to this new 
activity contemporaneously with the development of the Philosophy of Nature. It 
would hardly be possible to recognize the leading spirit in this new development, 
from his published works; but the man whom Pander and K. E. von Baer 
acknowledge as their master must be considered as the soul of this movement, 
and this man is Ignatius Dollinger. It is with deep gratitude I remember, for 
my own part, the influence that learned and benevolent man had upon my studies 
and early scientific application, during the four years I spent in his house, in 
Munich, from 1827 to 1831; to him I am indebted for an acquaintance with what 
was then known of the development of animals, prior to the publication of the 
great work of Baer; and from his lectures 1 first learned to appreciate the im- 
portance of Embryology to Physiology and Zoology. The investigations of Pander1 
upon the development of the chicken in the egg, which have opened the series 
of those truly original researches in Embryology of which Germany may justly 
be proud, were made under the direction and with the cooperation of Dollinger, 
and were soon followed by the more extensive works of Rathke and Baer, whom 
the civilized world acknowledges as the founders of modern Embryology. 
The principles of classification propounded by K. E. von Baer seem never to 
have been noticed by systematic writers, and yet they not only deserve the most 
careful consideration, but it may fairly be said that no naturalist besides Cuvier 
has exhibited so deep an insight into the true character of a natural system, 
1 Pander, Beitriige zur Entwickelungsgeschichte des Hiihnchens im Eie, Wurzburg, 1817, 1 vol. fol. 221 
Chap. III. 
EMBRYOLOGICAL SYSTEMS. 
supported by such an extensive acquaintance with the subject, as this great embry- 
ologist has in his " Scholien und Corallarien zu der Entwickelungsgeschichte des 
Hiilmchens im Eie."1 These principles are presented in the form of general pro- 
portions, rather than in the shape of a diagram with definite systematic names, and 
this may explain the neglect which it has experienced on the part of those who 
are better satisfied with words than with thoughts. A few abstracts, however, 
may show how richly the perusal of his work is likely to reward the reader. 
The results at which K. E. von Baer had arrived by his embryological inves- 
tigations, respecting the fundamental relations existing among animals, differed con- 
siderably from the ideas then prevailing. In order, therefore, to be correctly 
understood, he begins, with his accustomed accuracy and clearness, to present a 
condensed account of those opinions with which he disagreed, in these words: - 
"Few views of the relations existing in the organic world have received so 
much approbation as this: that the higher animal forms, in the several stages of 
the development of the individual, from the beginning of its existence to its 
complete formation, correspond to the permanent forms in the animal series, and 
that the development of the several animals follows the same laws as those of 
the entire animal series; that consequently the more highly organized animal, in 
its individual development, passes in all that is essential through the stages that 
are permanent below it, so that the periodical differences of the individual may 
be reduced to the differences of the permanent animal forms." 
Next, in order to have some standard of comparison with his embryological 
results, he discusses the relative position of the different permanent types of ani- 
mals, as follows: - 
" It is especially important that we should distinguish between the degree of 
perfection in the animal structure and the type of organization. The degree 
of perfection of the animal structure consists in the greater or less heteroge- 
neousness of the elementary parts, and the separate divisions of a complicated 
apparatus, - in one word, in the greater histological and morphological differen- 
tiation. The more uniform the whole mass of the body is, the lower the 
degree of perfection; it is a stage higher when nerve and muscle, blood and 
cellular tissue, are sharply distinguished. In proportion to the difference between 
these parts, is the development of the animal life in its different tendencies; or, 
to express it more accurately, the more the animal life is developed in its several 
tendencies, the more heterogeneous are the elementary parts which this life brings 
into action. The same is true of the single parts of any apparatus. That organ- 
1 Ueber Entwickelungsgeschichte der Thiere, 
Beobachtung und Reflexion von Dr. Karl Ernst von 
Baer, Konigsberg, 1828, 4to. - See also Acta Nova 
Acad. Leop. Caesar, vol. 13, and Meckel's Arch., 1826. 222 
ESSAY ON CLASSIFICATION. 
Part I. 
ization is higher in which the separate parts of an entire system differ more among 
themselves, and each part has greater individuality, than that in which the whole 
is more uniform. I call type, the relations of organic elements and organs, as far 
as their position is concerned. This relation of position is the expression of cer- 
tain fundamental connections in the tendency of the individual relations of life; 
as, for instance, of the receiving and discharging poles of the body. The type 
is altogether distinct from the degree of perfection, so that the same type may 
include many degrees of perfection, and, vice versa, the same degree of perfec- 
tion may be reached in several types. The degree of perfection, combined with 
the type, first determines those great animal groups which have been called classes.1 
The confounding of the degree of perfection with the type of organization seems 
the cause of much mistaken classification, and in the evident distinction between 
these two relations we have sufficient proof that the different animal forms do 
not present one uniserial development, from the Monad up to Man." 
The types he has recognized are: - 
I. The Peripheric Type. The essential contrasts in this type are between the 
centre and the periphery.2 The organic functions of life are carried on in antag- 
onistic relations from the centre to the circumference. Corresponding to this, the 
whole organization radiates around a common centre. There exists besides only 
the contrast between above and below, but in a weaker degree; that between 
right and left, or before and behind, is not at all noticeable, and the motion is 
therefore undetermined in its direction. As the whole organization radiates from 
one focus, so are the centres of all the organic systems arranged, ring-like, around 
it, as, for instance, the stomach, the nerves and vessels, (if these parts are devel- 
oped,) and the branches extending from them into the rays. What we find in 
one ray is repeated in every other, the radiation being always from the centre 
outwards, and every ray bearing the same relation to it. 
II. The Longitudinal Type, as observed in the Vibrio, the Filaria, the Gordius, 
the Nais, and throughout the whole series of articulated animals. The contrast 
between the receiving and the discharging organs, which are placed at the two 
ends of the body, controls the whole organization. The mouth and the anus are 
1 From this statement it is plain that Baer 
has a very definite idea of the plan of structure, and 
that he has reached it by a very different road from 
that of Cuvier. It is clear, also, that he understands 
the distinction between a plan and its execution. 
But his ideas respecting the different features of 
structure are not quite so precise. He does not 
distinguish, for instance, between the complication 
of structure as determining the relative rank of 
the orders, and the different ways in which, and the 
different means with which the plans are executed, 
as characteristic of the classes. 
2 Without translating verbatim the descriptions 
Baer gives of his types, which are greatly abridged 
here, they are reproduced as nearly as possible in 
his own words. Chap. III. 
EMBRYOLOGICAL SYSTEMS. 
223 
always at opposite ends, and usually also the sexual organs, though their opening 
is sometimes farther forward; this occurs, however, more frequently in the females, 
in which these organs have a double function, than in the males. When both 
sexual organs are removed from the posterior extremity, the opening in the female 
usually lies farther forward than in the male. So is it in the Myriapods and 
the Crabs. The Leeches and Earthworms present a rare exception. The recep- 
tive pole being thus definitely fixed, the organs of senses, as instrumental to the 
receptivity of the nervous system, early reach an important degree of perfection. 
The intestinal canal, as well as the vascular stems and the nervous system, extend 
through the whole length of the body, and all organic motion in these animals 
has the same prevailing direction. Only subordinate branches of these organs 
arise laterally, and chiefly wherever the general contrast, manifested in the whole 
length is repeated in such a manner that, for each separate segment, the same 
contrast arises anew, in connection with the essential elements of the whole organ- 
ism. Hence the tendency in these animals to divide into many segments in the 
direction of the longitudinal axis of the body. In the true Insects, undergoing 
metamorphosis, these segments unite again into three principal regions, in the first 
of which the life of the nerves prevails; in the second, motion; in the third, 
digestion; though neither of the three regions is wholly deprived of any one 
of these functions. Besides the opposition between before and behind, a less 
marked contrast is observed in a higher stage of development between above and 
below. A difference between right and left forms a rare exception, and is gen- 
erally wanting. Sensibility and irritability are particularly developed in this series. 
Motion is active, and directed more decidedly forward, in proportion as the lon- 
gitudinal axis prevails. When the body is contracted as in spiders and crabs, 
its direction is less decided. The plastic organs are little developed; glands, espe- 
cially, are rare, and mostly replaced by simple tubes. 
III. The Massive Type. We may thus call the type of Mollusks, for neither 
length nor surface prevails in them, but the whole body and its separate parts are 
formed rather in round masses which may be either hollow or solid. As the chief 
contrast of their structure is not between the opposite ends of the body, nor between 
the centre and periphery, there is almost throughout this type an absence of sym- 
metry. Generally the discharging pole is to the right of the receptive one. 
The discharging pole, however, is either near the receptive one, or removed from 
it, and approximated to the posterior extremity of the body. As the tract of 
the digestive apparatus is always determined by these two poles, it is more or 
less arched; in its simplest form it is only a single arch, as in Plumatella. 
When that canal is long, it is curled up in a spiral in the centre, and the spiral 
probably has its definite laws. For instance, the anterior part of the alimentary 
canal appears to be always placed under the posterior. The principal currents 224 
ESSAY ON CLASSIFICATION. 
Part I. 
of blood are also in arches, which do not coincide with the medial line of the 
body. The nervous system consists of diffused ganglia, united by threads, the 
larger ones being around the oesophagus. The nervous system and the organs 
of sense appear late; the motions are slow and powerless. 
IV. The Vertebrate Type. This is, as it were, composed of the preceding 
types, as we distinguish an animal and a vegetative system of the body, which, 
though influencing one another in their development, have singly a peculiar typical 
organization. In the animal system, the articulation reminds us of the second 
type, and the discharging and receiving organs are also placed at opposite ends. 
There is, however, a marked difference between the Articulates and the Vertebrates, 
for the animal system of the Vertebrates is not only doubled along the two sides, 
but at the same time upwards and downwards, in such a way that the two lateral 
walls which unite below circumscribe the vegetative system, while the two tending 
upward surround a central organ of the animal life, the brain and spinal marrow, 
which is wanting in Invertebrates. The solid frame represents this type most com- 
pletely, as from its medial axis, the backbone, there arise upward arches which close 
in an upper crest, and downward arches which unite, more or less, in a lower crest. 
Corresponding to this we see four rows of nervous threads along the spinal marrow, 
which itself contains four strings, and a quadripartite grey mass. The muscles 
of the trunk form also four principal masses, which are particularly distinct in the 
Fishes. The animal system is therefore doubly symmetrical in its arrangement. It 
might easily be shown how the vegetative systems of the body correspond to the 
type of Mollusks, though influenced by the animal system. 
From the illustrations accompanying this discussion of the great types or branches 
of the animal kingdom, and still more from the paper published by K. E. von 
Baer in the Nova Acta,1 it is evident, that he perceived more clearly and earlier 
than any other naturalist, the true relations of the lowest animals to their respective 
branches. He includes neither Bryozoa nor Intestinal Worms among Radiata, as 
Cuvier, and after him so many modern writers, did, but correctly refers the former 
to the Mollusks and the latter to the Articulates. 
Comparing these four types with the embryonic development, von Baer shows 
that there is only a general similarity between the lower animals and the embryonic 
stages of the higher ones, arising mainly from the absence of differentiation in the 
body, and not from a typical resemblance. The embryo does not pass from one 
type to the other; on the contrary, the type of each animal is defined from the 
1 Beitrage zur Kenntniss der niedern Thiere, 
Nova Acta Academiae Naturae Curiosorum, vol. 13, 
Part 2, 1827, containing seven papers, upon Aspido- 
gaster, Distoma, and others, Cercaria, Nitzschia, Poly- 
stoma, Planaria, and the general affinities of all 
animals. These " Beitriige," and the papers in which 
Cuvier characterized for the first time the four great 
types of the animal kingdom, are among the most 
important contributions to general Zoology ever 
published. Chap. III. 
EMBRYOLOGICAL SYSTEMS. 
225 
beginning and controls the whole development. The embryo of the Vertebrate 
is a Vertebrate from the beginning, and does not exhibit at any time a corre- 
spondence with the Invertebrates. The embryos of Vertebrates do not pass in 
their development through other permanent types of animals. The fundamental 
type is first developed, afterwards more and more subordinate characters appear. 
From a more general type, the more special is manifested, and the more two forms 
of animals differ, the earlier must their development be traced back to discern 
an agreement between them. It is barely possible that in their first beginning 
all animals are alike and present only hollow spheres, but the individual develop- 
ment of the higher animals certainly does not pass through the permanent forms 
of lower ones. What is common in a higher group of animals is always sooner 
developed in their embryos than what is special; out of that which is most general 
arises that which is less general, until that which is most special appears. Each 
embryo of a given type of animals, instead of passing through other definite types, 
becomes on the contrary more and more unlike them. An embryo of a higher type 
is, therefore, never identical with another animal type, but only with an embryo. 
Thus far do the statements of von Baer extend.1 It is evident from this, that 
he has clearly perceived the limitation of the different modes of embryonic develop- 
ment within the respective branches of the animal kingdom, but it is equally 
certain that his assertions are too general to furnish a key for the comparison of 
the successive changes which the different types undergo within their respective 
limits, and that he is still vaguely under the impression, that the development 
corresponds in its individualization to the degrees of complication of structure. 
1 The account which Huxley gives of Baer's 
views, (see Baden Powell's Essays, Appendix 7, 
p. 495,) is incorrect. Baer did not " demonstrate 
that the classification of Cuvier was, in the main, 
simply the expression of the fact, that there are 
certain common plans of development in the animal 
kingdom," etc., for Cuvier recognized these plans in 
the structure of the animals, before Baer traced 
their development, and Baer himself protests against 
an identification of his views with those of Cuvier. 
(Baer's Entwick., p. 7.) Nor has Baer demon- 
strated the " doctrine of the unity of organization 
of all animals," and placed it " upon a footing as 
secure as the law of gravitation," and arrived at " the 
grandest law," that, up to a certain point, the develop- 
ment "followed a plan common to all animals." On 
the contrary, Baer admits four distinct types of 
animals, and four modes of development. He only 
adds: " It is barely possible that in their first begin- 
ning all animals are alike." Huxley must also 
have overlooked Cuvier's introduction to the " Regne 
Animal," (2d edit., vol. 1, p. 48, quoted verbatim 
above, p. 193,) when he stated that Cuvier "did not 
attempt to discover upon what plans animals are con- 
structed, but to ascertain in what manner the facts of 
animal organizations could be thrown into the fewest 
possible propositions." On the contrary, Cuvier's 
special object, for many years, has been to point out 
these plans, and to show that they are characterized 
by peculiar structures, while Baer's merit consists 
in having discovered four modes of development, which 
coincide with the branches of the animal kingdom, 
in which Cuvier recognized four different plans of 
structure. Huxley is equally mistaken when he says 
that Cuvier adopted the nervous system " as the base 
of his great divisions." 226 
ESSAY ON CLASSIFICATION. 
Part I. 
This could hardly be otherwise, as long as the different categories of the structure 
of animals had not been clearly distinguished.1 
CLASSIFICATION OF K. E. VON BAER. 
In conformity with his embryological investigations, K. E. von Baer proposes the following classification. 
I. Peripheric Type. (Radiata.) Evolutio radiata. The development proceeds from a centre, producing 
identical parts in a radiating order. 
II. Massive Type. (Mollusca.) Evolutio contorta. The development produces identical parts curved 
around a conical or other space. 
III. Longitudinal Type. (Articulata.) Evolutio gemina. The development produces identical parts 
arising on both sides of an axis and closing up along a line opposite the axis. 
IV. Doubly Symmetrical Type. (Vertebrata.) Evolutio bigemina. The development produces identical 
parts arising on both sides of an axis, growing upwards and downwards, and shutting up along 
two lines, so that the inner layer of the germ is inclosed below and the upper layer above. The 
embryos of these animals have a dorsal cord, dorsal plates, and ventral plates, a nervous tube 
and branchial fissures. 
1°. They acquire branchial fringes; 
a. But no genuine lungs are developed. 
a. The skeleton is not ossified. Cartilagineous Fishes. 
The skeleton is ossified. Fishes proper. 
b. Lungs are formed. Amphibia. 
a. The branchial fringes remain. Sirens. 
The branchial fringes disappear. Urodela and Anura. 
2°. They acquire an allantois, but 
a. Have no umbilical cord; 
a. Nor wings and air sacs. Reptiles. 
But wings and air sacs. Birds. 
b. Have an umbilical cord. Mammalia. 
«. Which disappears early; 
1°. Without connection with the mother. Monotremata. 
2°. After a short connection with the mother. M a r s u p i a 1 i a . 
ft. Which is longer persistent; 
1°. The yolk sac continues to grow for a long time. 
The allantois grows little. R o d e n t i a. 
The allantois grows moderately. I n secti vora. 
The allantois grows much. C a r n iv o r a . 
2°. The yolk sac increases slightly. 
The allantois grows little. Umbilical cord very long. Monkeys and Man. 
The allantois continues to grow for a long time. Placenta in simple masses. 
Ruminants. 
The allantois continues to grow for a long time. Placenta spreading. Pachyderms 
and Cetacea. 
1 Compare Chap. II., Sect. 1 to 9. Chap. III. 
EMBRYOLOGICAL SYSTEMS. 
227 
CLASSIFICATION OF VAN BENEDEN. 
Van Beneden has also proposed a classification based upon Embryology, which was first sketched in 
his paper upon the Embryology of Bryozoa: Recherches sur l'anatomie, la physiologic et 1 ' embryogenie des 
Bryozoaires, Bruxelles, 1845, 4to., and afterwards extended in his Comparative Anatomy: Anatomie comparee, 
Bruxelles, (without date, but probably from the year 1855,) 1 vol. 12mo. 
I. Hypocotyledones or Hypovitellians. (Vertebrata.) The vitellus enters the body from the ven- 
tral side. 
Cl. 1. Mammalia. (Primates, Cheiroptera, Insectivora, Rodentia, Carnivora, Edentata, Pro- 
boscidea, Ungulata, Sirenoidea, Cetacea.) 
Cl. 2. Birds. (Psittaceae, Rapaces, Passeres, Columbae, Gallinae, Struthiones, Grallae, Palmipedes.) 
Cl. 3. Reptiles. (Crocodili, Chelonii, Ophidii, Saurii, Pterodactyli, Simosauri, Plesiosauri, 
Ichthyosauri.) 
Cl. 4. Batrachians. (Labyrinthodontes, Peromelia, Anura, Urodela, Lepidosirenia.) 
Cl. 5. Fishes. (Plagiostomi, Ganoidei, Teleostei, Cyclostomi, Leptocardii.) 
II. Epicotyledones or Epivitellians. (Articulata.) The vitellus enters the body from the dorsal 
side. 
Cl. 6. Insects. (Coleoptera, Nevroptera, Strepsiptera, Hymenoptera, Lepidoptera, Diptera, Orthop- 
tera, Hemiptera, Thysanura, Parasita.) 
Cl. 7. Myriapodes. (Diplopoda, Chilopoda.) 
Cl. 8. Arachnides. (Scorpiones, Araneae, Acari, Tardigrada.) 
Cl. 9. Crustacea. (Decapoda, Stomapoda, Amphipoda, Isopoda, Laemodipoda, Phyllopoda, Lophy- 
ropoda, Xiphosura, Siphonostoma, Myzostoma, and Cirripedia.) 
III. Allocotyledones or Allovitellians. (Mollusco-Radiaria.) The vitellus enters the body neither 
from the ventral nor from the dorsal side. 
Cl. 10. Mol lu sea. Including Cephalopoda, Gasteropoda, Poecilopoda, and Brachiopoda. (Acephala, 
Tunicata, and Bryozoa.) 
Cl. 11. Worms. (Malacopoda, Annelides, Siponculides, Nemertini, Nematodes, Acanthocephali, 
Scoleides, Hirudinei.) 
Cl. 12. Echinoderms. (Holothuriae, Echinides, Stellerides, Crinoides, Trematodes, Cestodes, 
Rotiferi, Planarias.) 
Cl. 13. Polyps. Including Tunicata, Bryozoa, Anthozoa, Alcyonaria, and Medusae, as orders. 
(Ctenophorm, Siphonophorae, Discophorae, Hydroids, Anthophoridae.) 
Cl. 14. Rhizopods. Only the genera mentioned. 
Cl. 15. Infusoria. Only genera and families mentioned. 
Van Beneden thinks the classification of Linnaeus truer to nature than either 
that of Cuvier or of de Blain ville, as the class of Worms of the Swedish naturalist 
corresponds to his Allocotyledones, that of Insects to his Hypocotyledones, and the 
four classes of Pisces, Amphibia, Aves, and Mammalia to his Hypocotyledones. 
He compares his primary divisions to the Dicotyledones, Monocotyledones, and 
Acotyledones of the vegetable kingdom. But he overlooks that the Cephalopods 228 
ESSAY ON CLASSIFICATION. 
Part I. 
are not Allocotyledones, and that any group of animals which unites Mollusks, Worms, 
and Radiates in one great mass cannot be founded upon correct principles. As 
to his classes, I can only say that if there are natural classes among animals, 
there never was a combination of animals proposed since Linnmus, less likely to 
answer to a philosophical idea of what a class may be, than that which unites 
Tunicata with Polyps and Acalephs. In his latest work, Van Beneden has introduced 
in this classification many important improvements and additions. Among the 
additions, the indication of the orders, which are introduced in brackets in the 
diagram above, deserve to be particularly noticed. These changes relate chiefly 
to the Mollusks and Polyps; the Tunicata and Bryozoa being removed from the 
Polyps to the Mollusks. The Acalephs and Polypi, however, are still considered 
as forming together one single class. 
The comparison, instituted by Van Beneden between his classification of the 
animal kingdom and that of the plants most generally adopted now, leads me to 
call again attention to the necessity of carefully scrutinizing anew the vegetable 
kingdom, with the view of ascertaining how far the results I have arrived at 
concerning the value of the different kinds of natural groups existing among 
animals,1 apply also to the plants. It would certainly be premature to assume, 
that because the branches of the animal kingdom are founded upon different plans 
of structure, the vegetable kingdom must necessarily be built also upon different 
plans. There are probably not so many different modes of development among 
plants as among animals; unless the reproduction by spores, by naked polyem- 
bryonic seeds, by angiospermous monocotyledonous seeds, and by angiospermous 
dicotyledonous seeds, connected with the structural differences exhibited by the 
Acotyledones, Gymnospermes, Monocotyledones, and Dicotyledones, be considered as 
amounting to an indication of different plans of structure. But even then these 
differences would not be so marked as those which distinguish the four branches 
of the animal kingdom. The limitation of classes and orders, which presents com- 
paratively little difficulty in the animal kingdom, is least advanced among plants, 
whilst botanists have thus far been much more accurate than zoologists in charac- 
terizing families. This is, no doubt, chiefly owing to the peculiarities of the two 
organic kingdoms. 
It must be further remarked, that in the classification of Van Beneden the 
animals united under the name of Allocotyledones are built upon such entirely 
different plans of structure, that their combination should of itself satisfy any 
unprejudiced observer that any principle which unites them in that way cannot 
be true to nature. 
1 See Chap. IL, p. 137 to 178. Chap. III. 
EMBRYOLOGICAL SYSTEMS. 
229 
DIAGRAM OF THE DEVELOPMENT OF ANIMALS BY KOLLIKER. 
Kolliker, (A.,) in his Entwickelungsgeschichte der Cephalopoden, Zurich, 1844, 1 vol. 4to., p. 175, 
has submitted the following diagram of the development of the animal kingdom. 
A. The embryo arises from a primitive part. (Evolutio ex una parte.) 
1°. It grows in two directions, with bilateral symmetry. (Evolutio bigemina.) 
a. The dorsal plates close up. Vertebrata. 
b. The dorsal plates remain open and are transformed into limbs. Articulata. 
2°. It grows uniformly in every direction. (Evolutio radiata.) And 
a. Incloses the embryonal vesicle entirely. 
a. This takes place very early. Gasteropoda and Acephala. 
This takes place late. (Temporary vitelline sac.) L i m a x. 
b. Contracts above the embryonal vesicle. (Genuine vitelline sac.) Cephalopoda. 
A. The whole body of the embryo arises simultaneously. (Evolutio ex omnibus partibus.) 
1°. It grows in the direction of its transverse axis, 
a. With its hind body. Radiata. (Echinoderms.) 
b. With the fore body, and 
a. The hind body does not grow. Acalephs. 
The hind body grows longitudinally. Polypi. 
2°. It grows in the direction of its longitudinal axis. Worms. 
I have already shown how unnatural a zoological system must be which is 
based upon a distinction between total or partial segmentation of the yolk.1 No 
more can a diagram of the development of animals, which adopts this difference 
as fundamental, be true to nature, even though it is based upon real facts. We 
ought never to single out isolated features, by which animals may be united or sep- 
arated, as most anatomists do; our aim should rather be to ascertain their general 
relations, as Cuvier and K. E. von Baer have so beautifully shown.2 I think also, 
that the homology of the limbs of Articulata and the dorsal plates of Vertebrata 
is more than questionable. The distinction, introduced between Polyps and Acalephs 
and these and the other Radiates, is not any better founded. It seems also quite 
inappropriate to call the development of Mollusks, evolutio radiata, especially after 
Baer had designated, under that same name, the mode of formation of the branch 
of Radiates, for which it is far better adapted. 
1 Chap. III., Sect. 1, p. 171. 
2 The principles of classification advocated by 
Baer are so clearly expressed by him, that I cannot 
resist the temptation of quoting some passages from 
the paper already mentioned above, p. 224, especially 
now, when I feel called upon to oppose the views of 
one of his most distinguished colleagues. " Vor alien 
Dingen muss man, um eine richtige Einsicht in die 
gegenseitige. Verwandtschaft der Thiere zu erlangen, 
die verschiedenen Organisationstypen 
von den verschiedenen Stufen der Aus- 
b i 1 d u n g stets unterscheiden. Dass man diesen 
Unterschied gewbhnlich nicht im Auge behalten hat, 
scheint uns zu den sonderbarsten Zusammenstel- 
lungen gefiihrt zu haben." Beitrage, etc., Acta 
Nova, vol. 13, p. 739. 230 
ESSAY ON CLASSIFICATION. 
Part I. 
CLASSIFICATION OF VOGT. 
I. Vf.rtebrata. Yolk ventral. 
Cl. 1. Mammalia. 1°. Aplacentaria; Ord. Monotremata,Marsupialia. 2°. Placen- 
taria. Ser. 1. Ord. Cetacea, Pachydermata, Solidungula, Ruminantia, and Edentata; 
S. 2. Pinnipedia, Carnivora ; N. 3. Insectivora, Volitantia, Glires, Quadrumana, Bimana. 
Cl. 2. Aves. Ser. 1. Insessores; Ord. Columbae, Oscines, Clamatores, Scansores, Rapta- 
tores ; Ser. 2. Autophagi; Ord. Natatores, Grallatores, Gallinacea, Cursores. 
Cl. 3. Re pt ilia. Ord. Ophidia, Sauria, Pterodactylia, Hydrosauria, and Chelonia. 
Cl. 4. Amphibia. Ord. Lepidota, Apoda, Caudata, Anura. 
Cl. 5. Pisces. Ord. Leptocardia, Cyclostomata, Selachia, Ganoidea, Teleostia. 
II. Articulata. Yolk dorsal. 
Cl. G. Insecta. Subcl. 1. Ametabola; Ord. Aptera. Subcl. 2. Hemimetabola; 
Ord. Hemiptera and Orthoptera. Subcl. 3. Holometabola; Ord. Diptera, Lep- 
idoptera, Strepsiptera, Nevroptera, Coleoptera, Hymenoptera. 
Cl. 7. M y r i a p o d a. Only divided into families. 
Cl. 8. Arachnida. Series 1. Pycnogonida and Tardigrada; Ord. Acarina, Araneida. 
Series 2. With three families. 
Cl. 9. Crustacea. Subcl. 1. E n t o m o s tr ac a; Ord. Cirripedia, Parasita, Copepoda, 
Phyllopoda, Trilobita, Ostracoda. Subcl. 2. Xi pho sura. Subcl. 3. Podoph- 
t h a 1 m a ; Ord. Stomapoda, Decapoda. Subcl. 4. Edriophthalma; Ord. Lae- 
mipoda, Amphipoda, Isopoda. 
HI. Cephalopoda. Yolk cephalic. 
Cl. 10. Cephalopoda. Ord. Tetrabranchiata and Dibranchiata. 
IV. Mollusca. Irregular disposition of organs. 
Cl. 11. Cephalophora. Subcl. 1. Pteropoda. Subcl. 2. Heteropoda. Subcl. 
3. Gasteropoda; Ord. Branchiata and Pulmonata. - Chitonida. 
Cl. 12. Acephala. Subcl. 1. Brach iopod a; Ord. Rudista, Brachiopoda. Subcl. 2. 
Lamellibranchia; Ord. Pleurochoncha, Orthoconcha, Inclusa. 
Contrast between the Embryo and the Yolk 
Transformation of the whole Yolk into the Embryo. 
Cl. 13. Tunicata. Ord. Ascidiae, Biphora. 
Cl. 14. Ctenophora. Only subdivided into families. 
Cl. 15. Bryozoa. Ord. Stelmatopoda, Lophopoda. 
Molluscoidea. 
V. Vermes. Organs bilateral. 
Cl. 16. Annelida. Ord. Hirudinea, Gephyrea, Scoleina, Tubicola, Errantia. 
Cl. 17. Rotatoria. Ord. Sessilia, Natantia. 
Cl. 18. Platy elm ia. 1°. Ord. Cestoidea, Trematoda. 2°. Ord. Planarida, Nemertina. 
Cl. 19. Nematelmia. Ord. Gregarinea, Acanthocephala, Gordiacei, Nematoidei. 
VI. Radiata. Organs radiate. 
Cl. 20. Echinodermata. Ord. Crinoidea, Stellerida, Echinida, Holotliurida. 
Cl. 21. Siphonophora. Only subdivided into families. 
Cl. 22. Hydro medusae. Not clearly subdivided into orders. 
Cl. 23. Polypi. Ord. Hexactinia, Pentactinia, Octactinia. 
No Egg. 
VII. Protozoa. 
Cl. 24. Infusoria. Ord. Astoma and Stomatoda. 
Cl. 25. Rhizopoda. Ord. Monosomatia and Polythalamia. 231 
Chap. HI. 
EMBRYOLOGICAL SYSTEMS. 
The classification of Vogt (Zoologische Briefe, q. a., p. 180) presents several 
new features, one of which is particularly objectionable. I mean the separation ol 
the Cephalopoda from the other Mollusks, as a distinct primary division of the 
animal kingdom. Having adopted the fundamental distinction introduced by Kbl- 
liker between the animals in which the embryo is developed from the whole yolk, 
and those in which it arises from a distinct part of it, Vogt was no doubt led 
to this step in consequence of his interesting investigations upon Actaeon, in which 
he found a relation of the embryo to the yolk differing greatly from that observed 
by Kblliker in Cephalopods. But as I have already shown above, this cannot 
any more justify their separation, as branches, than the total segmentation of the 
yolk of Mammalia could justify the separation of the latter from the other Verte- 
brates. Had the distinction made by Vogt, between Cephalopods and the other 
Mollusks, the value he assigns to it, Limax should also be separated from the 
other Gasteropods. The assertion that Protozoa produce no eggs, deserves no special 
consideration after what has already been said in the preceding sections respecting 
the animals themselves. As to the transfer of the Ctenophora to the type of 
Mollusks, it can in no way be maintained. 
Before closing this sketch of the systems of Zoology, I cannot forego the 
opportunity of adding one general remark. If we remember how completely inde- 
pendent the investigations of K. E. von Baer were from those of Cuvier, how 
different the point of view was from which they treated their subject, the one 
considering chiefly the mode of development of animals, while the other looked 
mainly to their structure; if we further consider how closely the general results 
at which they have arrived agree throughout, it is impossible not to be deeply 
impressed with confidence in the opinion they both advocate, that the animal king- 
dom exhibits four primary divisions, the representatives of which are organized 
upon four different plans of structure, and grow up according to four different 
modes of development. This confidence is further increased when we perceive 
that the new primary groups which have been proposed since are neither char- 
acterized by such different plans, nor developed according to such different modes of 
development, but exhibit simply minor differences. It is, indeed, a very unfortu- 
nate tendency, which prevails now almost universally among naturalists, with refer- 
ence to all kinds of groups, of whatever value they may be, from the branches 
down to the species, to separate at once from one another any types which exhibit 
marked differences, without even inquiring first whether these differences are of 
a kind that justifies such separations. In our systems, the quantitative element 
of differentiation prevails too exclusively over the qualitative. If such distinc- 
tions are introduced under well-sounding names, they are almost certain to be 
adopted; as if science gained any thing by concealing a difficulty under a Latin 232 
ESSAY ON CLASSIFICATION. 
Part I. 
or Greek name, or was advanced by the additional burden of a new nomencla- 
ture. Another objectionable practice, prevailing quite as extensively also, consists 
in the change of names, or the modification of the extent and meaning of old ones, 
without the addition of new information or of new views. If this practice is 
not abandoned, it will necessarily end in making Natural History a mere matter 
of nomenclature, instead of fostering its higher philosophical character. Nowhere 
is this abuse of a useless multiplication of names so keenly felt as in the nomen- 
clature of the fruits of plants, which exhibits neither insight into vegetable mor- 
phology, nor even accurate observation of the material facts. 
May we not return to the methods of such men as Cuvier and Baer, who 
were never ashamed of expressing their doubts in difficult cases, and were always 
ready to call the attention of other observers to questionable points, instead of 
covering up the deficiency of their information by high-sounding words! 
In this rapid review of the history of Zoology, I have omitted several classi- 
fications, such as those of Kaup and Van der Hoeven, which might have afforded 
an opportunity for other remarks, but I have already extended this digression 
far enough to show how the standards I have proposed in my second chapter 
may assist us in testing the value of the different kinds of groups generally 
adopted in our classifications, and this was from the beginning my principal object 
in this inquiry. The next step should now be to apply these standards also to 
the minor divisions of the animal kingdom, down to the genera and species, and 
to do this for every class singly, with special reference to the works of mono- 
graphers. But this is such an herculean task, that it can only be accomplished 
by the combined efforts of all naturalists, during many years to come. PAET II. 
NORTH AMERICAN TESTUDINATA. NORTH AMERICAN TESTUDINATA. 
CHAPTER FIRST. 
THE ORDER OF TESTUDINATA; ITS RANK, CLASSIFICATION, AND 
GENERAL CHARACTERS. 
SECTION I. 
RANK OF THE TESTUDINATA. 
The necessity of reviewing critically the North American Testudinata,1 in order 
to obtain a well-founded standard of comparison between the successive changes 
in the development of those species whose embryology I have examined, and the 
full-grown representatives of the types inhabiting the continent of North America, 
affords me a welcome opportunity of testing the principles of classification discussed 
in the first part of this work. It will be seen from this examination that, though 
their systematic arrangement requires here and there considerable modifications, 
yet the progress of science during this century has been such, that the changes 
I propose to introduce in the most generally adopted classification of the Testu- 
dinata are sometimes only confirmations of modifications already hinted at by pre- 
vious writers, whose opinions have not been sustained from want of satisfactory 
1 The name Testudinata being older than that 
of Chelonians, and yet entirely synonymous with it, 
I deem it necessary to retain it in future as the sys- 
tematic name of this order. The name Chelonians 
is, however, so generally adopted, that it may not be 
desirable to discard it altogether from our illustrations. 
I shall therefore still use it whenever this group is 
contrasted with the Saurians and Ophidians, as they 
were named together, according to the same prin- 
ciple. 236 
AMERICAN TESTUDINATA. 
Part II. 
evidence, though they were undoubtedly led to their results by that instinctive 
appreciation of the true relations among organized beings, which, in the history of 
science, is so often found to precede the practical demonstration and establishment 
of final results. Certainly, it is an unquestionable fact, that correct views are 
frequently propounded upon subjects of natural science, the proof of which, in the 
first imperfect state of our knowledge, is still wanting. In the case before us, we 
shall see how the practice of naturalists has generally led them to results which 
have not been, till now, susceptible of demonstration; but I hold that the possi- 
bility of thus accounting in the end for views instinctively adopted, and so often 
generally accepted, is in itself satisfactory evidence that the principles which fur- 
nish the final demonstration are true to nature. 
It might seem superfluous here to show that the class of Reptiles belongs 
to the type of Vertebrates, did it not afford an opportunity of showing that the 
definition of the great branches of the animal kingdom given above is correct. 
It has been stated1 that these primary divisions did not rest upon peculiar struc- 
tures, upon a distinct combination of given systems of organs, but exclusively upon 
a plan of structure. To show that Reptiles are Vertebrates, it may be sufficient, 
in practice, to exhibit their solid internal frame; but that this cannot be considered 
as the essential characteristic of a vertebrated animal is amply proved by the 
fact that Amphioxus no more has a skeleton, properly speaking, than the Myxi- 
noids and Petromyzontes; yet no one doubts that their true position is among 
Vertebrates. Again, in Testudinata, the largest part of the skeleton is truly exter- 
nal, their bony box being only covered by comparatively thin scales or a naked 
skin. There is, indeed, no class in which a greater diversity of structure is exhib- 
ited than among Reptiles; for, without mentioning the Batrachians, which constitute 
a class by themselves, what extraordinary difference is there not between Snakes, 
Lizards, and Turtles ! To show that notwithstanding this variety of structure, these 
animals actually belong to the branch of Vertebrata, is the object I have in 
view; and if it can be shown that so diversified a class belongs to that type, accord- 
ing to our understanding of the term branch, we shall have the required proof 
that our definition is true to nature. Now I have stated that branches are founded 
upon different plans of structure. What is, then, that plan in Vertebrates which 
unites Amphioxus, Cyclostomes, Sharks, Skates, Bony Fishes, Ichthyoids, Salamanders, 
Toads, Frogs, Snakes, Lizards, Crocodiles, Turtles, Birds, Whales, Marsupials, our com- 
mon Quadrupeds, Bats, Monkeys, and Man, which includes them all in one and the 
same group, and shows that group to be natural ? 
The body of all Vertebrates represents a double tube, one above the other, 
separated by a longitudinal axis, and varying in amplitude and in form at dif- 
1 See Part L, Chap. 2, Sect. 1, p. 141-144. Chap. I. 
RANK OF THE TESTUDINATA. 
237 
ferent points of their longitudinal diameter. These tubes are surrounded by walls, 
varying in thickness, as the spaces they inclose vary in size, the upper one con- 
taining the centres of the nervous system, the lower one the organs through which 
life is maintained; while the walls, in connection with the intervening longitudinal 
axis, constitute a locomotive apparatus, and serve also to sustain the relations with 
the surrounding media. 
These characteristics of the type of Vertebrates do not necessarily imply a definite 
structure; they apply as well to the imperfectly organized Amphioxus as to Man, for 
they do not involve the idea of a distinct head, nor that of locomotive appendages 
arranged in pairs, nor that of a branchial or pulmonary system of respiration, nor that 
of a heart as the centre of circulation, nor indeed any of those anatomical and histo- 
logical differences or peculiarities which are constantly and, in my opinion, errone- 
ously introduced in the characteristics of the great types of the animal kingdom. 
The external development of the skeleton of the Turtle no longer seems an 
anomaly, when we remember that it forms a part of those walls which surround 
the spinal cavity on the one hand, and the abdominal cavity on the other. 
If we next consider the Reptiles as a class, we must Temember that ever since 
Linnaeus these animals have been considered as one class. Cuvier, and with him 
all herpetologists, have agreed in considering them all as one class. We find 
de Blainville, for the first time, insisting upon the separation of the Batrachians 
from the other Reptiles as a distinct class. This view has also been adopted by 
Milne-Edwards, while Wagler has separated a few of their extinct types, the 
Ichthyosauri, the Plesiosauri, and the Pterodactyli, to unite them with the Orni- 
thorhynchus and Echidna as one class, under the name of Gryphi. The incon- 
gruity of this combination is so obvious, now that these fossil animals have been 
described in such a masterly manner by R. Owen, that I will not dwell upon 
its artificial character here. But the separation of the Batrachians from the other 
Reptiles as a class deserves a special notice, and if the definition I have given 
above of a class, as such, is correct, the result cannot be doubtful. I have stated 
that a class was defined by the manner in which the plan of structure of the 
branch to which it belongs is carried out. I have condensed that definition by 
saying, that the limitation of a class is a question of ways and means. Now, 
before applying this definition to the question of the separation of Batrachians 
from other Reptiles, I would make two remarks: In the first place, that this 
definition was not made to suit the case, but was arrived at by a critical con- 
sideration of the foundation upon which those classes rest, about whose natural 
limits there have never existed great doubts among naturalists, such as the 
class of Mammalia, that of Birds, that of Cephalopods, that of Gasteropods, that 
of Insects, that of Crustacea, and that of Echinoderms; in the second place, that 238 
AMERICAN TESTUDINATA. 
Part II. 
it is entirely erroneous to consider, as is universally done, that the classes exhibit 
modifications of the plan of structure of their respective branches. 
It is no more true that Fishes, Reptiles, Birds, and Mammalia exhibit respectively 
modifications of the plan of structure of Vertebrates, than that Insects, or Crus- 
tacea, or Worms are respectively modifications of the type of Articulates, or the 
different classes of Mollusks and Radiates, modifications of their respective types. 
A Fish is as truly a Vertebrate as any Bird or Mammal; the plan is not at 
all modified; it is only executed in different ways and with different means. 
The plan which characterizes Vertebrates is no more modified in the Fish than 
in the Reptile; the plan of Articulates is no more modified in Insects than in 
Crustacea or Worms; the plan of Mollusks, as a plan, is the same in Cephalopods 
as in Gasteropods and Acephala; that of Radiates, the same in Polyps as in 
Acalephs and Echinoderms. What, then, constitutes the difference of each class 
in the same branch ? It is the manner in which the plan of the branch to which 
they respectively belong is carried out. They are respectively characterized by 
the way in which, and the means with which, they are built up. The idea of 
radiation which is inherent in the plan of structure of Radiates is the same in all 
Radiates, in Polyps as well as in Medusas and Echinoderms; but in the Polyps it 
is expressed in one way, in the Acalephs in another, and in Echinoderms in still 
another. This is equally true of all the other classes, with reference to the plan 
of their respective branches. The different ways in which, and the different means 
with which each plan is executed in its respective classes, go far to show that 
the branches themselves are founded in nature, for the means employed in carrying 
out these different plans in a variety of ways, in their different classes, are every- 
where homological, and homological only within the limits of the same branch. 
We can trace no true homology between the systems of organs in Vertebrates 
and those in Articulates, nor between these and those of Mollusks; and a critical 
examination shows that the structure of Radiates is not homological with that of 
Mollusks. 
Truly homological systems of organs, then, more or less complicated, constitute 
class characters; but, again, these homologies are only general as far as the branch 
is concerned, while within each class special homologies only can be traced. Had 
these distinctions been made before, what an amount of confused discussion might 
have been spared respecting homologies in the animal kingdom! I trust this state- 
ment, the correctness of which may easily be tested by a comparison of the 
Batrachians and the true Reptiles, will put an end to the useless and puerile 
attempts to homologize every point of ossification in any class of the Vertebrates 
with some part or other of the skeleton of all the other members of that type. 
I hope also it may prevent such fanciful investigations from being extended into 
the study of the other systems of organs. Chap. I. 
RANK OF THE TESTUDINATA. 
239 
Now, to return to the question of the natural limitation of Reptiles, it must be 
obvious that if classes differ by the manner in which the plan of their branch is 
carried out, or by the ways and means employed in framing their structure, we 
cannot suppose that animals which, like Batrachians, lay a large number of small 
eggs, the yolk of which is segmented in the well-known manner, to produce an 
embryo, without amnios and allantois, undergoing extensive metamorphosis after 
it is hatched, furnished with external gills, which actually perform respiratory func- 
tions, even though they may disappear at a later period of life, the skin of 
which is naked, etc.,1 belong to the same class as the true Reptiles, the skin 
of which is covered with horny scales, which lay few, and comparatively large 
eggs > surrounded with a shell, the yolk of which undergoes only a superficial 
segmentation, and from which is formed an embryo inclosed in an amnios, and 
afterwards in an allantois, and which, after being hatched, undergoes no marked 
transformation, etc. The conclusion that Batrachians and Reptiles constitute two 
distinct classes, the first of which is indeed more closely allied to Fishes than to 
the true Reptiles, is not only of great zoological importance, but has also the 
most direct bearing upon the question of the order of succession of Vertebrates 
in geological times, and cannot fail to give a new interest to our investigations 
upon this subject, as well as to increase the precision of our knowledge respecting 
the first appearance of Reptiles upon earth. 
It will indeed be obvious at once, that if all the so-called Reptiles which have 
been mentioned as occurring in the carboniferous beds and even in strata below 
the coal, belong to the class of Batrachians and not to that of genuine Reptiles, 
the inference to be drawn from the presence of such animals during these ancient 
geological periods cannot be the same, and instead of leading to the assumption 
that conditions of existence similar to those which sustain our Reptiles prevailed 
as far back as these remains are found, we shall only have the evidence that 
the conditions essential to the life of Batrachians, but not to that of true Reptiles, 
were established then. 
After this separation of the Batrachians from the true Reptiles, we have only 
three orders left in the class of Reptiles proper: the Ophidians, the Saurians, and 
the Chelonians. It would lead me too far from my immediate subject, were I to 
examine here, whether this is the most natural subdivision of Reptiles into orders. 
I shall limit myself, therefore, to the consideration of the Chelonians alone, remark- 
ing only, that whether this division be natural or not, whether we include the 
Crocodilians in the same order as the true Lizards, or whether we regard them 
with their fossil representatives as a distinct order, or whether we consider the 
1 See further details in any anatomical text-book. 240 
AMERICAN TESTUDINATA. 
Part II. 
Ichthyosauri, the Plesiosauri, the Pterodactyli, the Dinosauri, etc., as constituting 
several additional orders, these groups, as zoological divisions, have in themselves 
the character of orders, that is to say, they exhibit, when compared with one 
another, various degrees of complication of their structure, and stand, with refer- 
ence to one another, higher or lower. It cannot be doubted, for instance, that 
compared with Lizards, the Snakes are an inferior group, and that the Chelonians, 
in which the different regions of the body are so distinctly marked and in which 
the head for the first time acquires a greater movability upon the neck, stand 
above the others, approaching indeed, in many respects, the class of Birds, especially 
the lower families of aquatic Birds, both in their form and in their mode of 
existence. 
Now, this gradation, acknowledged by all, inasmuch as all herpetologists place 
the Chelonians at the head of this class and next to them the Saurians, while 
the Ophidians occupy a lower position, will serve as an illustration of my definition 
of orders as natural groups, characterized by the different degrees of complication of 
the special structure of their class, which complications determine their relative rank 
or standing. I would not, however, in this connection forget that some naturalists, 
Strauss1 among others, have of late considered the Chelonians as a distinct class, 
and not as an order among Reptiles. Now, let us apply the test of our rules 
to this suggestion, remembering here again that these rules have been drawn from 
those classes of the animal kingdom, such as the Echinoderms, Acalephs, and Polyps, 
in which the orders are still more distinctly marked out in nature than in the 
one now under consideration. 
To constitute a class apart from Ophidians and Saurians, the structure of 
Chelonians ought to be built up in a different way and with different means from 
that of Saurians and Ophidians. And now, is this the case? The Chelonians, 
like Saurians and Ophidians, undergo a development so identical, that we need 
only compare the investigations of Rathke upon that subject with those contained 
in this volume, to settle any doubts on that point. And as to structure, what 
difference is there, except differences in complication of structure, between Ophidians, 
Saurians, and Chelonians, both in their nervous systems and organs of senses, 
in their locomotive apparatus and in their intestines ? Is not even the skeleton 
truly homological in all of them?2 We cannot fail, therefore, to consider the 
view as fully sustained, that Chelonians represent an order, and nothing but an 
order, in the class of true Reptiles. 
1 Strauss-Durkheim, (II.,) Theologie de la Na- 
ture, Paris, 1852, 3 vols. 8vo.; vol. 1, p. 99 and 398. 
2 For further evidence that the structure of the 
Chelonians is truly homological with that of Saurians 
and Ophidians, and that the position of their limbs 
and the frame of their shield does not place them 
in an exceptional position, with reference to the 
other Reptiles, see below, Sect. G of this chapter. Chap. I. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
241 
SECTION II. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
Whatever be the name admitted to designate this remarkable group of the 
animal kingdom, and whatever be the rank or dignity assigned to it, whether 
simply considered as a genus, or a family, or an order, all naturalists, with the 
exception of Strauss,1 agree in regarding the Turtles as a natural division in the 
class of Reptiles. They differ only with respect to its standing in the class, the 
extremes of opinion being between Linnaeus, who admits it only as a genus, and 
Strauss-Durkheim, who considers it as a distinct class. We have already seen 
that the correct view is that which considers it as an order.2 
It is more difficult to determine the value of the minor groups into which 
the Testudinata have been subdivided. Without entering into more details upon 
the subject than are found in most works on Herpetology, we shall hardly be 
able to form a just estimate of the real value of all these divisions, especially as 
few authors agree upon this point with one another. Linnaeus, for instance, unites 
all the Turtles he knew in one genus, including the marine as well as the fresh- 
water and land species. Brongniart,3 for the first time, considers them as a distinct 
order, under the name "Cheloniens," and divides them into three genera: Testudo, 
Emys, and Chelonia. Cuvier, a few years later in his "Regne Animal," enumerates 
five genera in that order, but without any further divisions. Oppel,4 as early as 
1811, before enumerating the genera, introduces two higher divisions, under the 
names of Chelonii and Amy dm tfor those Turtles which have oar-like or paddle 
feet, and those in which the fingers are distinguishable. These divisions of Oppel 
correspond to the sections Pinnata and Digitata of Merrem and Bell.6 Gray,6 
1 Compare Part IL, Chap. I., Sect. 1, p. 240. 
2 The various names applied by different authors 
to this order, are: Testudinata, Klein, Quadrup. 
Disp. Lipsiae, 1751 ; adopted by Oppel in 1811; 
by Merrem in 1820; by Fitzinger in 1826; by Bell 
in 1828 ; by Bonaparte in 1832 ; by LeConte in 1854. 
Testudines, adopted by Wagler in 1830. Che- 
LONli, proposed by Brongniart in 1800 ; adopted by 
Cuvier in 1817 ; by Gray in 1825 ; by Wiegmann 
in 1832; by Dumeril and Bibron in 1835; by 
Bonaparte in 1836; by Holbrook in 1842. Forni- 
CATA, proposed by Haworth in 1825. Sterri- 
Chrotes, proposed by Ritgen in 1828. Tylopoda, 
proposed by F. Meyer in 1849. 
8 Brongniart, (Al.,) Essay d'une Classification 
naturelie des Reptiles, Paris, 1805, 4to. 
4 Oppel, (M.,) Die Ordnungen, Familien und 
Gattungen der Reptilien, Munchen, 1811, 1 vol., 8vo. 
5 Merrem, (B.,) Tentamen Systematis Amphi- 
biorum, Marburg, 1820, 1 vol., 8vo. - Bell, (Tn.,) 
Characters of the Order, Families, and Genera of 
Testudinata, Zobl. Journal, 1828. 
6 Gray, (J. E.,) A Synopsis of the Genera of 
Reptiles and Amphibia, Annals of Philosophy, 1825. 242 
AMERICAN TESTUDINATA. 
Part II. 
without acknowledging these higher divisions, admits five families: Cheloniadae, 
Sphargidm, Trionicidm, Emydidae, and Testudinidm, as does also Bell, though this 
author divides these families between the two sections first introduced by Oppel, 
admitting however, for them, the names proposed by Merrem. 
Fitzinger1 has also five families in the order of Chelonians, but these do not 
exactly agree with those of Gray and Bell, for he unites the Sphargidae and the 
Chelonidae, but he adds another family under the name of Chelydoidea. Ritgen2 
admits, above the genera, three primary sections, Eretmochelones, Phyllopodochelones, 
and Podochelones; and so does also Wagler,3 though he changes the names of 
Ritgen into Oiacopodes, Steganopodes, and Tylopodes, calling them tribes, while 
the whole order is considered as including a single family. F. Meyer4 admits the 
same three subdivisions of his Tylopoda, (Testudinata,) but he gives them again 
new names. Wiegmann5 divides the Testudinata into five families, without higher 
groups, namely, Chelonm, Chersinae, Emydm, Chelydae, Chilotm. Swainson6 admits 
also five families, but with still different limits. Prince Canino,7 on the contrary, 
admits three families and four sub-families, but his three families do not correspond 
to the three sections or tribes of Wagler, as he unites the land and fresh-water 
Turtles into one family, while he considers the Trionychidae as a distinct family, 
which both Ritgen and Wagler place with the common fresh-water Turtles. The 
land and fresh-water Turtles are to Canino only sub-families. Dumeril and Bibron 
admit four families, Thalassites, Potamides, Elodites, and Chersites, and two sub- 
families.8 
These apparently most discrepant classifications, if we judge them merely by 
the different names employed by their authors, have in themselves more similarity 
than would at first appear. For instance, the three genera of Brongniart corre- 
spond to the three sections or tribes of Ritgen and of Wagler; the three fami- 
Notice that though Gray admits five families in 1831 
as in 1825, he limits them differently in the second 
than in the first Synopsis. 
1 Fitzinger, (L. J.,) Neue Classification der 
Reptilien, Wien, 1826, 1 vol., 4to.; see also his 
Systema Reptilium, Vindobonae, 1843, 1 vol., 8vo. 
2 Ritgen, (F. A.,) Versuch einer natiirlichen 
Eintheilung der Amphibien, Nova Acta Nat. Cur., 
1828, vol. 14. 
3 Wagler, (J.,) Natiirliches System der Amphi- 
bien, etc., Munchen und Stuttgart, 1830, 1 vol. 8vo. 
Atlas folio. 
4 Meyer, (Fr. I. C.,) System des Thierreichs, etc., 
Verhandl. Nat. Ver. Rheinl., 1849. 
6 WlEGMANN, (A. F. A.,) und Ruthe, (J.,) 
Handbuch der Zoologie, Berlin, 1832, 1 vol., 8vo. 
The Reptiles are by Wiegmann. 
6 Swainson, (W.,) Natural History and Classi- 
fication of Fishes, Amphibians, and Reptiles, London, 
1838-39, 2 vols., 12mo. These volumes form part 
of Dr. Lardner's Cabinet Cyclopedia. 
7 Bonaparte, (C. Lucian, Prince of Canino,) 
Saggio di una distribuzione metodica degli Animali 
Vertebrati, Roma, 1832, 8vo.; see also his Chelo- 
niorum Tabula analytica, Roma?, 1836. 
8 Dumeril, (A. M. C.,) et Bibron, (G.,) Erpe- 
tologie generale, ou Histoire naturelie complete des 
Reptiles, Paris, 1836, et seq., vol. 1. Chap. I. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
243 
lies, with two sub-families of Canino, correspond exactly to the four families of 
Dumeril and Bibron, the difference lying only in the separation, as families, of 
the Chersites and Elodites by Dumeril and Bibron, while they constitute two sub- 
families of the Testudinidm of Canino. Again, the Chersites, the united Potamides 
and Elodites of Dumeril and Bibron and their Thalassites represent the divisions 
of Ritgen and Wagler. I do not mean by this to say, that the separation of 
the Potamides and Elodites is not natural, but only to allude to the fact that 
Dumeril and Bibron's Thalassites correspond exactly to Ritgen's Eretmochelones and 
to Wagler's Oiacopodes, while their Chersites answer to Ritgen's Podochelones and 
to Wagler's Tylopodes, the Potamides and Elodites of the French herpetologists 
corresponding together to the Phyllopodochelones and Steganopodes of the two 
German writers. 
The agreement, and the discrepancies between these different systems, then, 
consist in this, that Oppel and Merrem and with them Bell, admit two higher 
subdivisions in the order of Testudinata, those with oar-like feet and those with 
distinct fingers, while Ritgen and Wagler admit three, distinguishing between those 
the visible fingers of which are webbed, and those in which they are entirely 
separated, while Dumeril and Bibron introduce a farther distinction between those 
with webbed feet and a scaly body and those with a naked carapace, the Emyds 
proper and the Trionyx. Canino maintains this distinction between the naked 
and scaly fresh-water Turtles, but as he unites all the scaly ones together, whether 
their fingers are webbed or not, his division includes the Chersites of Dumeril 
and Bibron as well as their Elodites. The sub-families which Dumeril and Bibron 
introduce among the Elodites are founded upon the mode of motion of the neck, 
which exhibits differences already noticed by Wagler in 1830. Bell, Gray, and 
Fitzinger, who have a still larger number of groups which they call families, have 
founded them upon the same features which have led Dumeril and Bibron to 
subdivide the Elodites. I do not here speak of the classifications of Fleming1 
and Latreille,2 which are too artificial to deserve special notice. 
Beyond these divisions, all authors mention only genera and sub-genera. Now, 
it must be obvious, from the agreement of all these writers in some points of 
their subdivisions of the Testudinata, that this order is not so homogeneous as to 
exclude higher divisions than genera in its classification. The point on which all 
agree is, the separation of the Turtles with oar-like, natatory organs of locomo- 
1 Fleming, (J.,) The Philosophy of Zoology, 
London, 1822, 2 vols., 8vo., divides the Chelonea, 
as he calls the Testudinata, into those with a movable 
and those with an immovable sternum. 
2 Latreille, (P. A.,) Families naturelies du 
regne animal, Paris, 1825, 1 vol., 8vo., divides the 
Chelonians into those which can retract their legs, 
Cryptopodes, and those which cannot, Gymnopodes. 244 
AMERICAN TESTUDINATA. 
Part II. 
tion from the rest of the order, in the farther subdivision of which we find, 
however, the greatest discrepancy among modern herpetologists. But, whether we 
subdivide the digitated Chelonians of Oppel and Merrem into two, or three, or 
more natural groups, the question at once arises, how these groups shall be called, 
whether they are sections, sub-orders, families, or tribes, names which in the chaos 
now prevailing in nomenclature might seem equally applicable to all and any of 
them, or whether nature points out a real difference between them. Let us 
consider, in the first place, the more extensive of these groups, such as they are 
admitted by Oppel under the names of Ciielonii and Amydae, and by Merrem and 
Bell under the names of Pinnata and Digitata. What do they indicate ? A differ- 
ence in the mode of locomotion, that is to say, a structural difference, and that 
difference is of such a kind that, whether consciously or unconsciously, all authors 
have regarded those Turtles which have pinnate limbs as inferior to those in which 
the fingers are distinct. We find, at least, that in all works in which the animal 
kingdom is arranged in a descending order, the digitated Testudinata are mentioned 
first, the pinnate last, and where these are subdivided, as they have been by 
Ritgen, Wagler, Dumeril and Bibron, and Canino, those with club feet are placed 
above those with webbed fingers. Their intention is therefore evident, to mark 
the respective' rank of the Testudinata in these subdivisions of the order, a grada- 
tion which is, however, not founded upon differences in the whole structure, but 
only on such as are prominently marked in some parts of the body. In as far 
then as this is correct, these divisions all partake of the character of orders; 
they are akin to what we have called orders, inasmuch as orders are founded 
upon the gradation or complication of structure, but they are not real orders, 
inasmuch as that gradation does not extend to all the organic systems of their 
structure. At least, it is neither so extensive as to afford a means of com- 
parison of any of them singly with any other order of the class, without involv- 
ing the enumeration of characters common to all; nor is the element of form, 
which is so important in the characteristics of families, introduced distinctly in any 
of these minor groups. 
We can, therefore, consider these divisions only as sub-orders; and the precision 
with which their gradation can be pointed out from the Thalassites through the Pota- 
mides and Elodites to the Chersites leaves no doubt in my mind that, whether 
two general groups are to be adopted under the head of Testudinata, as Oppel, 
Merrem, and Bell recognize, or three, as Ritgen and Wagler admit, or three com- 
bined in the manner in which Canino has them, or four, as Dumeril and Bibron 
have them, these divisions must be considered as sub-orders, since they express 
a gradation within the order, or, in other words, are founded, under certain limi- 
tations, upon characters of the same kind as those on which the whole order is Chap. I. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
245 
founded, though these characteristics are confined to certain parts, instead of extend- 
ing to the whole organization. 
The next question which we have to consider here is, whether these sub-orders 
exhaust the natural subdivisions existing between the order and the genera; or, 
in other words, whether in this class the orders coincide with the families or not, 
for we have not yet examined the question whether every order has necessarily 
more than one family or not. My remarks in the third chapter of the first 
part of this work can leave no doubt that each of the four branches of the animal 
kingdom contains several classes, for we have seen that every one of them dis- 
plays the plan of structure on which it is founded, as carried out in different 
ways and with different means. But we have seen from a supposed case, that 
if such a class included only a few species, or even several genera, or perhaps 
one or more families, there might be no foundation for a distinction of orders, 
if all these species, genera, and families presented only such a diversity of ultimate 
structure and such modifications of form as would not distinctly indicate among 
them a difference of rank, an appreciable gradation.1 But where a class contains 
groups in which such differences as mark gradation and rank are clearly percep- 
tible, then we have distinct orders, even should these orders coincide with the 
limits of the families, that is to say, be combined with such modifications of 
form that, though expressing a gradation, these groups would correspond with the 
characters upon which families are to be founded. Now it remains for us to 
examine whether this is the case among Testudinata; and since the Chelonii 
constitute so natural a sub-order, when contrasted with the Triony chida?, the Emy- 
doidae, and the Testudinina, we may select it as a test of the existence of sub- 
orders in nature, and we shall afterwards extend our remarks to the other minor 
groups with the view of ascertaining how many divisions of this kind there truly 
are in the order of Testudinata. 
Ever since naturalists have attempted to subdivide the Testudinata, those with 
pinnate limbs have been considered as a natural group, raised by most to the dig- 
nity of a family, and embracing, in all modern classifications at least, two genera, 
Chelonia and Sphargis, though some authors subdivide farther Chelonia into several 
genera, and even go so far as to consider Sphargis and Chelonia proper as the 
types of distinct families. Now, whether that group contains one or two families, 
it unquestionably exhibits very great uniformity of structure as a group, when 
compared to the other Testudinata. In the first place, the dermal ossification 
remains imperfect; next, the limbs preserve through life a character which is uni- 
form in Testudinata, as long as their development is not complete, that is to say, 
1 See Part L, Chap. 1, Sect. 1, p. 5-7 246 
AMERICAN TESTUDINATA. 
Part II. 
they retain undivided fingers, such as the embryos have, even exaggerating this 
feature, in the adult, into an elongated paddle for the anterior limbs. Chelonii con- 
stitute, then, the lowest sub-order in the order of Testudinata; and it will presently 
be seen that its characters are not derived from the form of its representatives. 
Those who are sufficiently conversant with the subject will be aware that when 
characters derived from the form have been added to the other characters in order 
to distinguish the Chelonii, they have answered but indifferently; indeed, the form 
of Sphargis and that of Chelonia differ much more than that of Emydoidae compared 
with Testudinina. The scaly Chelonii, the Chelonioidae proper, have their shield 
more or less heart-shaped, and the posterior angle is not prolonged into a projecting 
point extending far over the tail, as is the case among the naked Chelonii, the 
Sphargididae. For this and other reasons which it would be superfluous to mention 
here, as my object is not now to characterize every group of Testudinata minutely, 
I hold that Chelonioidae proper and Sphargididae, which differ by their form, are two 
distinct families in the sub-order of Chelonii, and that this sub-order exhibits struc- 
tural features of inferiority when contrasted with the other Testudinata. Gray and 
Bell, in their early publications, had, in my opinion, correctly distinguished Sphargidae 
and Chelonidae1 as families, even though they afterwards gave up that distinction 
and placed them incorrectly upon one level with Trionyx, Emys, and Testudo. In 
this respect, Fitzinger presented this matter in a more correct light when, like 
Oppel, he contrasted the united Chelonii with the other groups of the order; but 
I believe he was mistaken in urging the reunion of the families of Sphargidae and 
Chelonidae. If the view which I have presented of the case is correct, the marine 
Turtles would constitute a sub-order, for which a variety of names had been 
proposed: that of Pterodactyl! by Fr. Meyer, that of Thalassites by Dumeril and 
Bibron, that of Oiacopodes by Wagler, that of Eretmochelones by Ritgen, that of 
Pinnata by Merrem, and that of Chelonii by Oppel, all of which are perfectly 
synonymous. That of Oppel, which is the oldest, having been proposed in 1811, 
should have made all the others superfluous, and ought now to be retained. This 
sub-order includes two families, the Chelonioidae and the Sphargididae, as these differ 
in form. Their characteristics are fully illustrated in the next chapter. 
The scarcity of Trionyx in European museums seems to have prevented so accu- 
rate a study of that group as of the others. It is, at least, surprising that some 
of the ablest herpetologists have failed to perceive how greatly they differ from 
the other fresh-water Turtles. Wagler unhesitatingly unites them with the Emyds, 
while quite recently Major LeConte has united them with Chelydra.2 Yet, as 
1 When I quote the systematic names of original 
writers, I follow their spelling; in other cases, I 
adopt that which seems to me correct. 
2 LeConte, (Major,) Catalogue of the North 
American Testudinata, in Proc. Ac. Nat. Sc., Phila. 
vii., 1854. 247 
Chap. I. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
early as 1825, Gray had distinguished them as a family, which was adopted by 
Bell, by Fitzinger, by Canino, and by Dumeril and Bibron, the latter only chang- 
ing the name of Trionychidm into that of Potamides. This group constitutes one 
of the most natural families among Turtles, at once recognized by the flat, thin 
shield of an elegant oval form, by the long neck, the pointed head, and project- 
ing nose. But the question is farther, whether this family can be associated in 
one sub-order with Emys and Testudo, or not. If we consider the total absence 
of scales, the imperfect ossification of the shield, the absence of ossification of 
the margin, or the limited extent to which it is ossified, the slight protection of 
the jaw by a small, horny sheath, we cannot fail to recognize characters of 
inferiority in these features, when comparing them with those of the Emyds and 
Testudos; and I would not hesitate to consider that family, though exhibiting alone 
such characters, as forming a sub-order of the same organic value as that of the 
Chelonii, did we not observe similar differences between the Sphargididae and the 
true Chelonioidm, and had we not learned long ago that any amount of difference 
existing between two groups never constitutes a difference of kind. The question 
might even be raised, whether the very imperfect ossification of Aspidonectes, and 
especially the total absence of marginal scutes, do not place them below the Che- 
lonioidm. But when it is remembered that among Chelonii the ossification is still 
more imperfect, at least in Sphargis, and that the skin is as destitute of scales 
in this genus as in Trionyx, there can be little doubt left that all the peculiarities 
of Trionyx are only family characters. The structure of their limbs is almost as 
perfect as in Emys, and, as we shall see hereafter, their whole organization brings 
them close to the Emydoids, Chelys and Chelydra forming the intermediate links. 
The remaining two types, Emys and Testudo, evidently stand, in every respect, 
highest among the Amy dm or Digitata, and close the series of Testudinata. 
I greatly question the propriety of separating Trionyx, Chelys, Emys, and Tes- 
tudo as groups coequal with Chelonia, as so many herpetologists do. There are 
many modifications in the degree of separation of the fingers among them, which 
alone do not establish differences of the same kind nor of the same degree as 
between these on one side and Chelonia on the other, even though as to ossification, 
development of scales, and armature of jaws, Trionyx differs somewhat from Emys 
and Testudo, while the two latter agree as closely as possible with one another. 
I would, therefore, consider Testudo, Emys, Chelys, and Trionyx together as one sub- 
order, showing the whole number of sub-orders among Testudinata to be only two, 
Chelonii and Amyd.e, - the latter, however, including a number of distinct families, 
as I shall demonstrate presently. 
The same argument which has led us to consider Sphargis and Chelonia as 
distinct families, leads naturally to the separation of a number of families among 248 
AMERICAN TESTUDINATA. 
Part II. 
this second sub-order, called Amydae by Oppel. In the first place, we notice 
the Trionychidae, so remarkable for the peculiarities already alluded to; next we 
have the North American Chelydroidae with their fossil European representative; next 
the South American Chelyoidae, the Hydraspididae, the Cinosternoidae, the Emydoidae 
proper; and lastly, the Testudinina, each of which groups presents typical patterns 
of form which are constant within their limits, and strikingly contrasted when 
compared with one another. For it is not true, as is so frequently repeated, that 
the fresh-water Turtles are flat and broad when compared with the land Turtles. 
Some of our marsh Turtles, and especially our Ozotheca, are quite as high compara- 
tively, and certainly as narrow as any of the land Turtles, whilst the Chelydroidae 
with their carinated backs, their dentated margin, their broad, flat heads, their 
narrow, cross-like sternum, their large tail, their imperfectly retractile limbs and 
head, differ far more from the other Emydoidae than any land Turtles. I do 
not, therefore, hesitate for a moment to consider these two groups as two distinct 
families. Of the family of Chelydroidae, there are two species in the United States 
belonging to two distinct genera, as I have ascertained that Chelydra Serpentina 
differs generically from the Chel. Temminckii And., for which I have proposed the 
name of Gypochdys Temminckii. Their thoroughly aquatic habits show them to be, 
next to Trionyx and Chelys, the lowest family among Amydae. Next to them, 
I would place the family of Cinosternoids, on account of their less extensive sternum 
and of their more movable pelvis. There can be no doubt that they constitute 
a family by themselves, when in addition to the difference of form already alluded 
to it is found that they have no odd bone in the sternum, so that their lower 
shield divides into symmetrical halves, along an uninterrupted straight suture, fol- 
lowing the middle line. The long-necked Hydraspids with retractile head, or rather 
whose head can be bent laterally and so protected under the shield, come next 
in order; but as they are all foreign to the United States, and I have had few 
opportunities for their study, I must omit any further mention of them. I would 
only recall, in this connection, the interesting fact that the types of land and 
fresh-water Turtles are so localized upon the surface of the globe, that, though the 
number of Testudinata is very great in the United States, not a single Hydraspid, 
for instance, is found within their limits, and only two Testudos occur in their 
southern parts, while the family of Chelydroids, on the contrary, belongs almost 
exclusively here, and is only found again in China. The true home of the 
genuine Emydoids is also North America, as the true home of the Chelyoids 
and Hydraspids is South America, though a few species of the latter family occur 
also in other parts of the world. 
As a family, the Emydoidae are easily characterized by their ovate form, swelling 
centrally, while the margin has a tendency to spread outward, in which last feature Chap. I. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
249 
they agree with the Chelydroids and Hydraspids, while, in that respect, they differ 
strikingly from the Cinosternoids, the margin of which has a tendency to round 
itself up and turn inwards, as is also the case in the genuine Testudos, which 
constitute the last and highest family of the whole order. We shall presently 
see that among our native Emydoids there are two species which have generally 
been referred to the same genus, the Cistudo Carolina and the C. Blandingii, one of 
which, however, is a genuine fresh-water species of the genus Emys, while the other 
is entirely terrestrial. 
The family of Testudinina has always been circumscribed within its natural 
limits, ever since it was first distinguished. 
Before we proceed to an analysis of the genera of the North American Testu- 
dinata, we may now recapitulate the results at which we have arrived respecting 
the general classification of the whole order, as follows: - 
Order, Testudinata, Klein. 
1st Sub-order, Chelonii, Opp. With two families, Chelonioidm and Sphar- 
gididae. 
2d Sub-order, Amydae, Opp. With seven families, Trionychidm, Chelyoidf®, 
Hydraspididae, Chelydroidae, Cinosternoidm, Emydoidae, and 
Testudinina. 
It should further be remarked that, as in all larger divisions of the animal 
kingdom, these families are not equally related to one another. The affinity of 
the Trionychidae to the other families is not so close as that which brings the 
Cinosternoids near the Chelydroids, or certain Emydoids near the Testudinina, or 
the Hydraspids near the Chelyoids; yet after testing all their characters as far as 
my opportunities permitted, I have come to the conclusion that the seven groups 
above enumerated as families under the head of the sub-order Amydse are truly 
natural families, characterized by different typical forms, which are defined by 
structural peculiarities, as we shall see more fully hereafter. The inequality among 
these families, in the degree of their relationship, is a feature which will appear 
objectionable, as long as the opinions respecting the supposed symmetry and equality 
of the natural divisions of animals, entertained at present by many scientific men, 
continue to prevail; and until the inequality of endowment characteristic of all 
organized beings is recognized as the law prevailing in the organic kingdoms, from 
the humblest individual to the most comprehensive types. 
My opportunities of investigation do not justify me in attempting to charac- 
terize all the genera of the order of Testudinata. I must limit myself, in this 
part of my subject, to a general review of those which have representatives in 250 
AMERICAN TESTUDINATA. 
Part II. 
North America, introducing only such comparisons with foreign ones as may be 
imperatively required to appreciate their mutual relations. 
All the genera thus far established among the Chelonii have representatives 
along the coast of the United States, and I am not aware that there are any 
genera of this sub-order, except those which have already been recognized by 
herpetologists: the family of Sphargididae, containing only one genus, the genus 
Sphargis; and the family of Chelonioidae proper, containing three genera, namely, 
Chelonia, Thalassochelys, and Eretmochelys. But as some of the most prominent 
herpetologists recognize only one genus in this family, I will give below my reasons 
for believing that the genera Thalassochelys and Eretmochelys are as well founded 
in nature as the genus Chelonia proper. 
Of the sub-order Amydae, the family of the Trionychidae has only four representa- 
tives in America, which however bear a very peculiar relation to the other mem- 
bers of the family; for while all the Trionyx of the old world are inhabitants of 
the tropical fresh waters, or at least occur only south of the twenty-first isothermal 
line, those of America are all found to the north of that very line, neither Central 
nor South America nourishing a single Trionyx, while in North America they range 
over the whole continent east of the Rocky Mountains, as far north as the great 
Canadian lakes and the upper St. Lawrence. 
If we were to judge by the opinion prevailing about the Chelydroidae a few 
years ago, it would appear that we had only one species of that family; and yet 
Dr. Holbrook, in his North American Herpetology, long ago described a second 
species, under the name of Chelonura Temminckii, which seems to have remained 
unknown to European writers, for all their references to this animal are either 
expressed with doubt, or are evidently mere compilations, or abstracts from the 
North American Herpetology. I have now in my possession a number of speci- 
mens of this species weighing between ten and fifty pounds, preserved in alcohol, 
and also several skeletons made from specimens presented to me by Prof. Baird, 
Prof. Chilton, Dr. Gessner, and Winthrop Sargent, Esq. I had, besides, an oppor- 
tunity of seeing two living specimens in their native waters, in the neighborhood 
of Mobile, one of which weighed about two hundred pounds, and many others 
which were sent to me alive by Mr. Sargent and which 1 preserved alive during 
the whole of last summer. 1 have, in addition, examined several very young ones, 
preserved in alcohol, which were forwarded to me by Prof. Baird and Dr. Nott. 
I can, therefore, not only vouch for the specific distinction of the two species, but 
am prepared to show that they differ generically, as a fuller comparison below, 
illustrated with many figures, will prove. (See also above, p. 248.) 
The family of the Chelyoidae has no North American representatives, nor has that 
of the Hydraspididae; but of the family of the Cinosternoidse we have two genera, Chap. I. 
SPECIAL CLASSIFICATION OF TESTUDINATA. 
251 
one of which is the well characterized genus Cinosternum of Spix. The opportuni- 
ties I have enjoyed for the examination of the representatives of these genera have 
satisfied me that the sexual differences among them are such as readily to be mis- 
taken for specific differences, which has actually been done again and again. The tail 
of the male, for instance, is always much longer than that of the female; the males 
have sharp asperities between the joints of the hind legs; moreover the color and 
ornamentation differ considerably. As a genus, however, Cinosternum is easily 
distinguished. Yet our common Mud-Turtle, (Ozotheca odorata,) has been referred 
to Cinosternum by some authors, and to Sternothmrus by others, until it was placed 
in the genus Staurotypus by Dumeril and Bibron. Having formerly had an oppor- 
tunity of examining, in Munich, the type on which Wagler founded the genus Stauro- 
typus, I can affirm that our species is by no means generically identical with Wag- 
ler's Staurotypus, and still less belongs to Bell's Sternothmrus, or to Spix's Cinoster- 
num. It constitutes, indeed, a genus for itself, which I have called Ozotheca^ the 
characters of which are intermediate between those of Staurotypus and those of 
Cinosternum. There are, in the southern parts of our country, other species of this 
genus, as I have had good opportunity of ascertaining, but I have no hesitation in 
saying that the characters according to which some of the species now admitted 
have been established in this family by Wagler, Dumeril and Bibron, Gray, and 
LeConte, may all be found upon specimens of different age, sex, and size, living 
together in the same pond in our Northern States, so that the true differences 
of our species are still to be pointed out. 
All herpetologists seem to agree about the limits of the genera Emys and Cis- 
tudo, though they differ about the name, Canino retaining the name of Terrapene 
for the group to which Dumeril and Bibron assign the name of Emys, and giving 
the name of Emys to that group which Dumeril and Bibron call Cistudo, and which 
Gray farther subdivides into Cistudo proper and Lutremys. The descriptions of our 
species below will show that the distinction introduced by Gray is truly founded, and 
that Cistudo and Lutremys are not only sub-genera, but constitute entirely distinct 
genera belonging even to different sub-families. As the name Cistudo was first assigned 
to the Cistudo Carolina, it is proper it should retain it, while it is equally proper 
that the group to which Gray assigns the name Lutremys should be called Emys, 
as it includes the European Emys, upon which the genus Emys was founded by Bron- 
gniart. More than twenty years ago, Canino had already called the attention of 
herpetologists to this point, and set it all right; yet no one has followed his sug- 
gestion, thus far. Accordingly, there exists in North America not a single Emys, 
properly speaking, among those which have been described under that generic name. 
Moreover, the species which have been referred to that genus do not, by any means, 
all belong to one and the same genus. 252 
AMERICAN TESTUDINATA. 
Part II. 
Since I have had an opportunity of comparing all the North American Testu- 
dinata with one another, alive,1 I cannot cease to wonder that the marked generic 
peculiarities of the Emydoids should have been so entirely overlooked. 1 have 
already stated (p. 24G) that the so-called Cistudo Blandingii is a true Emys; it is 
the North American representative of the common European Emys (Lutremys, Gray.} 
Now that its natural relations are accurately determined, it should henceforth be 
called Emys Meleagris, as this specific name is older than that of Blandingii. But, 
among the other North American Emydoids we find several other generic types. 
Emys scabra (serrata), Troostii and elegans (cumberlandensis) constitute a distinct 
genus, which I call Trachemys ; whilst Emys mobiliensis, concinna (fioridana), and 
rugosa (rubriventris) constitute another genus under the name of Ptychemys ; and 
Emys geographica and Lessueurii (E. pseudo-geographica) still another under the name 
of Graptemys. Emys picta, Bellii, and several new species, constitute also a distinct 
genus, already recognized by Gray, and called by him Chrysemys. Emys guttata is 
also the type of a distinct genus, which I call Nanemys. Emys Miihlenbergii is the 
type of the genus I have named Calemys, and Emys concentrica constitutes still 
another genus, already named Malaclemys by Gray; this and Chrysemys being the 
only ones thus far noticed as generically distinct from the other types of Emy- 
doids inhabiting North America. Emys reticulata constitutes also a new genus, 
Deirochelys ; Emys insculpta another, Glyptemys ; and Emys marmorata B. and G. 
(E. nigra, Hal.) still another, Actinemys. The North American Testudinina belong 
to the new genus, Xerobates. All these new genera and several new species, 
peculiar to the United States, are characterized below. 
SECTION III. 
ESSENTIAL CHARACTERS OF THE ORDER OF TESTUDINATA. 
There is scarcely any order among Vertebrates so well defined and so naturally 
circumscribed as that of the Turtles. The cycle of their modifications, notwith- 
standing the diversity of sub-orders, families, and genera which they include, is so 
narrow, the external systems of organs, even the proportions of the body, are so 
1 The number of living turtles I had an oppor- 
tunity of examining and preserving for months and 
years in my yard, will appear incredible to Eu- 
ropean naturalists. I have had them and their eggs 
by the thousands, thanks to the kindness of my 
friends in every part of the country; and I shall 
avail myself, in the next chapter, of the opportunity 
duly to mention all these favors, when enumerating 
singly all our species and the precise localities where 
they are found. Chap. I. 
CHARACTERS OF THE ORDER. 
253 
constant, that even the uninitiated will recognize a Turtle as a Turtle, as readily 
as they will know a Bird to be a Bird.1 It is not so with the other orders of 
Reptiles, the Snakes and Lizards. It is certainly easy to recognize in a Rattle- 
snake and a Leguan two entirely different animals, but it needs a scientific inves- 
tigation, and indeed a very accurate one, to distinguish the Rhinophis as a Snake, 
from the Anguis or Ophisaurus as a Lizard; indeed, in English, the Ophisaurus is 
commonly called a Snake, the Glass-Snake. All Turtles, on the contrary, are dis- 
tinctly comprised by all civilized languages under one name. What, then, is this 
something which so forcibly strikes the eye of the unlearned, and is so graphically 
expressed by the familiar names of these animals ? It is the stiff backbone, spreading 
into the shape of a shield: Schild-krbte, German, shield-toad; turtle, Saxon, perhaps 
from tart or tartsche, the shield of the old Germanic tribes; testudo, in Latin. 
Let us now consider, from this point of view, the remaining orders of the Rep- 
tiles, the Serpents and Saurians, and we shall see what deep truth is hinted at by 
this name of "Schild-krbte." The Snake moves only by means of the lateral motions 
of its vertebral column, together with the ribs; the Turtle only by means of its feet; 
and the Lizard, which stands between the two, by means of both together. We 
have a gradual series from the Apodes, or footless Reptiles, which creep upon the 
stomach, the Snakes, through the Lizards, up to the highest Reptiles, namely, the 
terrestrial Turtles, which stand upon four supports; and, to gain a true insight into 
the characters of the order of Testudinata, it is important to trace this series 
through its successive links. In so doing, we find the Pythons moving like all 
other serpents by means of horizontal undulations of the vertebral column, and the 
pressure of the ribs attached to it. But the anatomist finds, concealed under their 
anal scales, traces of hind feet, and even of the pelvis. These rudiments of limbs 
have as yet no locomotive function, but they hint at what is afterwards to appear in 
the higher types of the same class. The lowest Lizards, (and every zoologist con- 
siders as such the family of Glass-Snakes, Scincoidae,) begin with the European 
Anguis, in which traces of hind feet are concealed under the skin, but the only real 
1 Simple and trivial as this statement may seem, 
it involves a principle which neither naturalists nor 
general observers appear yet fully to understand, 
namely, that natural groups are not necessarily 
equally distinct, and that groups which seem equally 
distinct are not necessarily of the same value. No 
higher group in the animal kingdom is more clearly 
defined than the class of Birds, with perhaps the sole 
exception of the Turtles; but then Turtles constitute 
only an order in the class of Reptiles, and not a class 
for themselves; while the Reptiles as a class by no 
means present that uniformity of appearance so char- 
acteristic of the Birds. What is true of these two 
types within their limits is equally true of hundreds 
of other types within other limits,. Much of the 
uncertainty perceptible iij our classifications, from the 
highest divisions down to the limitation of the species, 
arises from a constant neglect of the universal in- 
equality which pervades both the animal and the 
vegetable kingdoms. 254 
AMERICAN TESTUDINATA. 
Part II. 
locomotive organ of which is still the vertebral column with the movable ribs, as in 
the Snakes. In the Dibamus of New Guinea, there appear, for the first time, visible 
extremities, small, slender, toeless, scaly hind feet. In the Bipes of New Holland 
these become somewhat larger, and in Brachymeles, rudiments of anterior extremities 
are added. In the genus Evesia, these extremities are still undivided; in the Brach- 
ymeles proper they have, in front and behind, two toes; in the South-Euro- 
pean Seps, we find already three toes in front and behind; in the Scincus five,1 
in front and behind, but the fore feet are still weak and do not yet carry the 
body so swiftly and easily over the earth as those of the Lizards, but these also, 
with their perfectly developed feet, are still assisted by the motion of the vertebral 
column. From this point of the series up to the Turtle, there is a great stride, 
for in them the head and neck are free, much freer than in any of the Saurians 
whatsoever. The vertebral column has become stiff; the four feet are the only 
locomotive organs; and yet in the marine Turtles, the fore feet exceed greatly in 
power the hind pair, and it is only in the land Turtles that we find at last all the 
four feet perfectly equal in strength, affording four props or supports, upon which 
the whole body moves slowly forward, like a house on rollers. 
This is the natural series of the orders in the class of true Reptiles. Let us 
now consider the class of Amphibians from the same point of view. The Caecilia, 
the lowest Batrachian, is a long-drawn, serpent-like animal, moving by means of 
undulations of the vertebral column. In one of our southern Ichthyoid Batrachians, 
called Siren, there arise two feeble feet in front, or rather a pair of diminutive 
anterior limbs project from behind the gills. In the German Proteus, or the North 
American Amphiuma, four legs are already perceptible, having from two to three 
toes, and the Salamanders, which at present extend over the whole surface of the 
globe, walk, like the Lizards, on four well developed feet, using like them, however, 
the whole dorsal column as a locomotive organ. From these, again, we have a 
stride up to the Frog. The spine has become stiff; all lateral motion has ceased 
in it, and, as in the Reptile when in its highest development, so with the most 
perfect Batrachian, the four feet are the only locomotive organs. This is the 
series of the Amphibians.2 
If we now compare the highest Reptile, the Turtle, with the highest Amphi- 
bian, the Frog, the locomotive organs in both being completely developed, and the 
spine serving no longer for locomotion, we find the latter ready to be applied to 
other purposes. A step towards this is made in the Frog. The caudal bone is 
separated sharply and distinctly from the rest of the spine, as is also the neck, 
1 For further details respecting the series of the 
family of Scincoids, see Part I., Chap. 1, Sect. 12. 
2 Compare the illustrations of this series in my 
Lectures on Comparative Embryology, p. 8 to 10. 255 
Chap. I. 
THE SHIELD. 
but both are still buried, as it were, in the general mass of the body. On the 
contrary, in the culminating Reptile, the Turtle, the neck is completely free from 
the mass of the body, and so also is the tail; but there is still a sort of visceral 
chest, inclosing the breast and abdomen. 
This general sketch of the essential characters of the Testudinata shows distinctly 
that their most prominent features are also those which assign to them the highest 
rank in their class. It is therefore plain, that the Testudinata, being a natural group, 
constitute an order in the class of Reptiles, acknowledged to be such by most zoolo- 
gists, while at the same time this typical group furnishes additional evidence that the 
characters I have considered above1 as ordinal characters are marked out, as such, 
in nature. It remains now to show, what is the degree of complication of their 
structure which assigns to them that rank in their class. The comparison insti- 
tuted here, between the leading groups of the true Reptiles and those of the 
Batrachians, shows already the two series to consist equally of groups presenting a 
natural gradation in their normal relations. We are, therefore, not only justified in 
considering them all as natural orders, but this gradation, within their respective 
limits, goes far also to show that the higher divisions under which they are com- 
bined partake of the character of classes, and that Reptiles proper and Amphib- 
ians are justly to be considered as two distinct classes. 
SECTION IV. 
THE SHIELD. 
We have found the main ordinal character of the Turtles, in contradistinction 
to other Reptiles, to consist in the nature of the dorsal column, which, in connec- 
tion with other elements, forms in Turtles one continuous shield upon the back. 
This dorsal shield, usually called by the French name "carapace," is connected 
by a bridge with another shield, commonly called " plastron," which covers the 
region of the breast and abdomen from below. These two shields together form 
a hard girdle around the soft organs of the trunk. 
If we take a Turtle of that family in which the idea or the type of Turtles is 
carried out the furthest, namely, a land Turtle, we find these shields built up of two 
very different elements, the skin and the true bony skeleton. If we analyze such 
a shield from the outside inwards, we see first a thick very hard and dry epidermis 
1 Part L, Chap. 2, Sect. 3, p. 150. 256 
AMERICAN TESTUDINATA. 
Part II. 
with its thin, soft, and wet matrix, the stratum Malpighii. Then, immediately under 
this, we find a bony plate. Now this bony plate consists of two elements, very differ- 
ent in their anatomical and physiological character; namely, first, of parts of* the true 
skeleton, the vertebra), the ribs, and the bones of the sternum; secondly, of ossifica- 
tions of the skin, or rather of the outer walls of the body, which overlie the true 
skeleton and fill out its framework, thus making one continuous bony shield of the 
vertebrae and ribs, and another of the sternal bones. These ossifications of the skin, 
commonly called the dermal skeleton, are divided into many fields, like a pavement, 
by sutures, the direction and extension of which are entirely independent of the 
underlying framework of the true skeleton. These fields are larger where they over- 
lie the bones of the true skeleton; they become smaller and thus relatively more 
numerous where they reach beyond it, namely, in the margin of the upper shield. 
As already stated, these marginal bony plates are mere ossifications of the skin 
extending beyond the ribs. The relative direction and extension, as well as the 
number of all these fields of the ossified skin, are very similar in the different 
families of Testudinata. 
This composition of the shield, from the elements described above, is common 
to all the land Turtles, to the Emydoidae, to the Cinosternoida), to the Chelydroidse, 
and to the South American, Eastern, and Australian Pleuroderae, the Chelyoidse 
and Hydraspididae. Thus far, we know only three groups which present any differ- 
ences in these respects, the Chelonioidae, the Sphargididm, and the Trionychidae. 
Though we find that in the Chelonioidae all the elements named above take part 
in building up their shield, still their dermal skeleton is very much reduced, while 
in land Turtles it makes up by far the largest part of the bony shield and actually 
grows into the true bony skeleton at the expense of the latter, in such a manner 
that parts of this disappear and are replaced by the ossification of the skin. In 
the Chelonioidse, on the contrary, the dermal skeleton fills only imperfectly the 
spaces between the ribs, but then it forms a regular row of marginal plates, 
and again scantily fills the spaces between the sternal bones. In Trionychidse, 
we observe the same partial development of the dermal skeleton, as it fills only 
to some extent the intercostal spaces and the spaces between the sternal bones, and 
forms but a few marginal plates, which may even be entirely wanting, as is the 
case in the Southeast African Cycloderma, recently discovered by Dr. Peters, and 
in our own Trionyx ferox and muticus. Finally, in Sphargis the dermal skele- 
ton is developed in a very different way, namely, as one continuous shield above, 
and another beneath, nowhere resting immediately upon the true skeleton, there 
remaining between the dermal and the bony skeleton a thick layer of corium, 
which never ossifies. This structure constitutes the most striking contrast when 
compared with Testudo, where the dermal shield actually grows into the true bony Chap. I. 
THE SKIN. 
257 
skeleton. Thus it appears that in Sphargis the trunk is inclosed in a dermal 
bony girdle which is circumscribed in front, behind, and on the two sides; under 
this solid envelope follows a coarse felt of soft corium without lime deposits, and 
under this finally lies the true skeleton. In Sphargis, the ossifications of the skin 
have thus least to do with the skeleton proper, while the connection of the dermal 
and the true skeleton is carried furthest in land Turtles. We may say, therefore, 
that if the type of Turtles is carried out the furthest in the genuine Testudinina, 
it is the least so in Sphargis. 
SECTION V. 
THE SKIN. 
The epidermis, the Malpighian layer, the corium, and the ossifications of the 
latter, are to be found in all Turtles, but they show the greatest variety in 
different families. We will analyze these different strata, proceeding from the 
outside inwards. 
The Epidermis. The epidermis of the head is of great importance in charac- 
terizing the order, the sub-orders, families, genera, species, and even the sexes of 
Turtles. The practised observer may, from the sheath of the jaw alone, recognize 
at least the genus. In all Turtles, the jaws are covered by a thick epidermis, 
which gives them the appearance of a genuine bill, more or less rounded in front, 
with sharp margins either smooth or denticulated. Such a bill is not found in 
any other Reptile, nor in any order of Vertebrata, except in two Mammalia, in all 
the Birds, and in the Tadpoles of the Batrachians. This horny sheath is errone- 
ously said to be wanting in some Turtles. We find it in all, even in the Triony- 
chidae, where the jaws are covered by fleshy lips, but it varies greatly in thickness; 
while it is rather thin in the Emydoidm, it forms in the Cinosternoidse a strong, 
sharp hook, which is stronger still in Chelydra, and strongest in Sphargis, which is 
very likely a carnivorous Turtle. In this last genus it has the form of a hook 
bill, more powerful than even the bill of the South American Harpyia. 
On the top and on the sides of the head the epidermis forms either one continu- 
ous layer, as in the Emydoidae, Cinosternoidae, Chelydroidae, and Trionychidae, or it 
is divided into a pavement of thicker plates, disposed either symmetrically, as in 
Chelonia, or more irregularly, as in Testudo. On the under surface of the head, 
on the chin and upper neck it is seldom thickened into distinct plates, but, no doubt 
in order to provide for its greater movability, it is usually only divided by wrinkles 258 
AMERICAN TESTUDINATA. 
Part II. 
into fields, as it is also all over the neck and in all those other parts of the 
trunk which are not covered by the shields of the back and the lower side. The 
epidermis of the legs varies very much, from the thin layer of the Trionychidse, 
in which it is only in some single places thickened into hard plates, to the horny, 
scaly, or plated stiff coat of the massive feet of the sea and land Turtles, Chelonia 
and Testudo, where there is very little or no motion of the different parts of 
the legs. In the Chelonioidm the epidermis of the last phalanges appears as a nail 
only in the thumb, while in Sphargis there is not even a trace of a nail to be 
found; in the Trionychidse it forms sharp, long, slim claws, in three fingers and in 
three toes; in the aquatic Emyds (Nectemyds) there are similar nails in all the 
fingers and in the toes. On the contrary, in the more terrestrial members of the 
family of Emydoidae, in Glyptemys insculpta, and still more in Cistudo, whose fingers 
and toes are less movable and frequently used for walking on land, the claws 
appear shorter and stouter, while in Testudo the whole coat of the fingers and 
toes has become a hoof, almost as in Pachyderms, serving as in the latter to carry 
the heavy load of the body. These epidermal formations in the legs and particu- 
larly those in the last phalanges, in connection with the epidermal formations of 
the jaws, are very important for the classification, as they indicate more clearly 
than any other external organ the mode of life of the animal in all its relations 
to the outer world. That the consideration of these parts leads really to natural 
divisions is seen not only in Turtles, but more distinctly still in Birds and Mam- 
malia; and the system of Linnaeus, founded upon such details, has assumed the 
character of a natural combination in the classification of these two classes, though, 
as he understood them, they still appear as artificial as his system of plants. 
The epidermis of the tail is mostly wrinkled or covered only by small scales, 
thus allowing to this organ a great movability. In the family of Chelydroidae 
only do we find, along the top of their long, powerful tail, a row of hard 
tubercles strengthening and protecting it as an organ of locomotion, and by no 
means interfering with its movability. In some land Turtles and in the genus 
Cinosternon, the end of the tail has a flat, rounded sheath, as in Testudo indica, 
or it has a pointed nail-like or even crooked tip, as in Cinosternon, particularly 
in the males. 
The most important features of the epidermis, and those most peculiar to Turtles, 
are found in the back and the lower shield. It is scarcely developed in two 
families, the Trionychidae (soft-shell Turtles) and the Sphargididae, in which it forms 
only a thin continuous layer upon the corium, as in naked Batrachians, while it is 
thick, horny, and divided into fields in all other Testudinata, that is to say, in 
all those Turtles in which the corium is entirely ossified. In the Trionychidse 
and Sphargidae there lies always a thick layer of soft, unossified corium, under Chap. I. 
THE SKIN. 
259 
the thin, elastic epidermis. As in all Vertebrata, so also is the epidermis in 
Turtles, composed of characteristic cells, of an hexagonal or irregular form, which 
are dry and flat near the surface, and more or less imbricated, while their contours 
are better defined the deeper we penetrate and the more we approach their matrix. 
But in relation to the mode of growth and the duration of these cells, upon a 
larger scale, up to the time when they are cast in moulting, we find the greatest 
variety among Turtles, as we find, indeed, among all the different types of Verte- 
brata. The differences in the epidermal formations, observed in Turtles, naturally 
lead us to expect such a diversity among them in particular. In the Sphargididm 
and the Trionychidae, I have had no opportunity of seeing a regular casting off of 
the epidermis, though there can be hardly any doubt that a change of the epidermis 
takes place here, and that it is effected by the dropping of single cells or of thin 
layers, for I have noticed it in Trionyx, as we find it in the epidermis of Frogs 
and of Man himself, in whom it is quite similar. But in all other Turtles, the 
nature of the epidermis, and therefore its moulting also, are entirely different. In 
Eretmochelys imbricata, the plates of the shield (the tortoise-shell of commerce) 
are very large, and imbricated one above the other. These plates increase only in 
front, where they are imbedded in a thick matrix, in the Malpighian layer, as in 
a case. As the plates enlarge in front, the older parts must move backwards, 
where they are worn off by external mechanical agencies. This process goes on 
so rapidly in these Turtles, that in a specimen of two feet in length, no trace 
of those primary scales, which covered the whole shield during the first year, 
could be found. This mode of growing and moulting, if we may call it so, is very 
similar to that in the human nail. But we find a very different process in land 
Turtles, and to some degree also in Cistudo, in which the plates rest entirely, 
in front and on the sides and behind, upon their matrix, in the Malpighian layer. 
They are not at all free and raised behind, as is the case in Eretmochelys, 
and thus they grow not only in front, but with their whole under surface and 
on all sides; hence it follows that we find upon the surface of each scale, around 
a small angular central plate, (the scale of the first year's growth,) a smaller or 
greater number of concentric stripes or regular annual rings, as they are exhibited 
on a transverse section of an old tree.1 
1 This is remarkably obvious in some specimens 
of the Xerobates carolinus (Testudo polyphemus) 
of our Southern and South-western States, and always 
in Testudo radiata of Madagascar, and in Testudo 
geometrica of the Cape of Good Hope. In rela- 
tion to the Gopher, (Test, polyphemus,) I have to 
remark that the plates of most adult specimens are 
perfectly smooth, so that their successive growth 
and their age can no longer be read upon the plates, 
as it is easy to do in many other species of that 
family. The Gopher, and perhaps also the Gala- 
pagos Turtle (T. indica) burrow into the ground 
and live in earth holes, and this accounts, perhaps, 
for their worn and polished plates. But why should 260 
AMERICAN TESTUDINATA. 
Part II. 
Thus we have two different modes of growth in the dermal plates of Testu- 
dinata: that of Eretmochelys on one hand, and that of Testudo on the other. 
Between these extremes, we have every possible intermediate feature. Thus, we 
find that in the Chelonioidae and Emydoidm, though the plates are not free 
behind as in Eretmochelys, but on the contrary lie with their whole under sur- 
face upon the stratum Malpighii, as in Testudo, they still grow almost exclusively 
in front and on the sides, showing only small additional stripes behind, or none 
at all. This is still more strikingly exhibited in the Cinosternoidm, and here it is 
in the direction of the Eretmochelys, as they show an evident inclination to an 
imbricated position of their plates. It is already visible in Cinosternon, especially 
in Cinosternon flavescens, but still more in the Ozotheca triquetra of our South- 
ern States, and also in our Northern Ozotheca odorata, when young. I have 
already had occasion to allude above to the moulting of the epidermis when 
speaking of Sphargis, Trionyx, and Eretmochelys; but 1 am persuaded that such 
a change in fact takes place in all Turtles. In Chrysemys picta, and in sev- 
eral other fresh-water Turtles, such as Trachemys elegans and scabra, Ptychemys 
concinna, Graptemys Lessueurii, etc., 1 saw in the spring the uppermost layer of 
the dermal plates cast off at once as one continuous, thin, mica-like scale all over 
the plate, and under it the fresh epidermis, showing beautifully by its transparency 
the colors of the Malpighian layer. This reminded me very much of the moulting 
of Snakes; but the difference consists in this, that in Snakes the epidermis is cast 
off as one continuous skin from the snout to the end of the tail, while in Turtles 
each scale casts its epidermis for itself. In Testudo, the casting off of the old epi- 
dermis is very different in different species, and even in different specimens of the 
same species.1 I have seen in many adult specimens of Xerobates carolinus, and 
still more distinctly in some old specimens of Testudo radiata, the central plate 
of the scales, that is the plate of the first year, perfectly preserved with all its 
fine granules, so sharp indeed that it seemed as if nothing had been cast from their 
surface, while others were entirely worn out. These facts show that further obser- 
vations are very much needed respecting the moulting of the Reptiles. Indeed, this 
subject requires to be studied anew in all Vertebrata.2 
other specimens of Gopher, which have the same 
mode of life, exhibit all the sculptures of their 
plates? We find the same difference between the 
specimens of Cistudo virginea, and still more between 
those of Glyptemys insculpta, the smooth variety 
of which has been described as a distinct species 
under the name of E. speciosa. 
1 See, above, p. 259, note on Gopher and Cistudo. 
2 I mean here particularly also the moulting of 
Mammalia and Birds, which is by no means so fully 
understood as it would appear from our handbooks. 
D. Weinland has presented interesting remarks upon 
this subject in a paper read before the Boston So- 
ciety of Natural History in the beginning of this 
year. See the Proceedings of the Boston Society 
of Nat. Hist, for 1856. Chap. I. 
THE SKIN. 
261 
The Colors in Turtles. The coloring of the lowest strata of the epidermis, the 
so-called Malpighian layer, has not yet, so far as I know, been the object of a 
special investigation. I deem it, therefore, worth our while to take up this point 
more fully than other parts of the ordinal characters. The uppermost dry part of 
the epidermis, the stratum comeum, which is so extensively developed in Turtles, 
exhibits as usually by far the smallest part of the colors; the most beautiful colors 
being included chiefly in the Malpighian layer. That stratum, on the contrary, is 
transparent, with a grayish lustre, like mica. Thus far only one Turtle is known 
in which this dry, horny layer contains all the coloring matter, at least as far as 
the colors are visible from outside, namely, Eretmochelys imbricata; and it is owing 
to this extraordinary circumstance that in the dry plates of this Turtle (the tortoise- 
shell) all their beautiful colors are preserved, even after the plates have been removed 
from the Malpighian layer. A homogeneous brownish lustre may be seen with 
the microscope in the epidermal cells, in all those places of the plate where it 
appears brown; there is, however, no trace of pigment cells, nor of any fluid, and 
that brownish color belongs only to the walls of the cells.1 Still more intense 
colors, often black, produced in the same way, are found in the thick plates of 
nearly all land Turtles, for instance, in Testudo radiata, polyphemus, indica, etc., and 
in some Chelonioidae, as in Chelonia Caouana and Mydas, but in all these the Mal- 
pighian layer, lying beneath the plates, also takes part in forming the colors which 
appear outside. 
The Malpighian layer, also called the pigment layer, is not only the matrix of 
the epidermis, but at the same time the bearer of the pigment in Turtles. It is moist 
and soft, and of very different thickness in different families, generally however thick 
enough to be readily separated as one continuous membrane from the dry, horny 
stratum which lies above it, as well as from the corium or bone which lies below. 
It is composed of large, round, transparent cells, lying not in plane layers, but 
rather imbricated. On, between, and beneath these cells lies the pigment, either 
in cells or as a free fluid in lacunes, or in one continuous layer. Thus we have 
to distinguish two different forms, under which the pigment occurs in Turtles: 
first, real pigment cells, which are always black or blackish brown, and filled with 
brownish pigment molecules, upon the amount of which in a cell depends its more 
or less dark tint; and secondly, a colored oily fluid, moistening generally the whole 
Malpighian layer, and not contained in regular cells. Under this second form 
appear the most various colors, such as the yellow, red, brown, and also sometimes 
black tints of our different kinds of Turtles. The most diversified play of colors 
is produced by the combinations of these free fluid colors, by their superposition 
1 As we find it also in some places of the human body. See Kdlliker Gewebelehre, p. 98, § 43. 262 
AMERICAN TESTUDINATA. 
Part II. 
and by their separation through cells of the Malpighian layer. Generally this fluid 
is again combined with the pigment cells described above, the forms of which, more 
or less radiated, more massive or more slender, produce again different effects. 
Under the microscope, the free fluid coloring matter looks generally yellowish, if 
the effect is yellow; reddish, if the effect is red. Water added to this fluid when 
taken from the living specimen, causes it to collect in larger and smaller drops, 
and then their oily character1 becomes evident by the characteristic blackish margin 
of the drops. We have still to mention another kind of color, which we see 
only in one genus of North American Turtles, namely, the white on the head of 
some specimens of the genus Cistudo. This appears under the microscope to be com- 
posed of grayish black heaps, and if these are farther isolated, we find them com- 
posed of thin transparent plates, breaking like glass. All these pieces together 
produce the impression of a white tint upon the eyes, by interference of the rays 
of light, just as the powder of glass, the smallest pieces of which are also trans- 
parent under the microscope. 
The range of variations which the colors exhibit in one and the same species, 
in many genera of our Testudinata, is almost incredible; and unless these variations 
are carefully studied, and their transitions watched for a long time, in every stage 
of growth, it is impossible to know how far they agree with the natural limita- 
tion of species. For this reason most descriptions of the colors of our Turtles 
are incomplete and unsatisfactory, being generally drawn from a few specimens. 
In several instances, nominal species have been distinguished merely upon differ- 
ences in the coloration. This has been done to the greatest extent in the genus 
Ptychemys, as we shall see hereafter. Generally speaking, there are, however, cer- 
tain tints which prevail in some species, while other tints are more common in 
other species, and in these cases the colors afford, to some extent, good specific 
characters. But it sometimes happens that not only the patterns of coloration, 
but even the colors themselves, are the same in every species of the same genus, 
so that coloration requires a special preliminary and extensive study for every genus, 
before it can be applied to the systematic characteristics of these animals. 
1 In relation to the nature of this oil, see D. 
Weinland on Birds' Feathers, in Cabanis, Journal 
fur Ornithologie for 1854. He supposes that the 
yellow oil turns reddish by a kind of oxydating 
process, and thus, perhaps, also the reddish to 
brown, and this to black. Such an oxydation takes 
place, as we know, for instance, with extravasated 
blood, which turns black very likely by a pro- 
cess of burning. It is true, this is a pathological ex- 
perience, and it may not seem proper here to refer to 
it; but pathology rests upon the same laws of organic 
chemistry as physiology. For studying these colors 
in Turtles, we recommend as fine objects the red and 
yellow rings on the marginal plates of Chrysemys 
picta and marginata. The beautiful brown-green 
color of the dorsal shield of the latter is produced 
by a network of black lacuna; lying on a homoge- 
neous layer of yellow oil. 263 
Chap. I. 
THE SKIN. 
The Corium. A thorough analysis of the corium is of the greatest interest 
in the study of the Turtles, because this part of the skin is the seat of all those 
deposits of lime which compose their dermal skeleton. The corium is composed of 
two very different layers: first, a layer of elastic fibres, immediately under the stra- 
tum Malpighii, consisting of the same kind of anastomozing, or rather netrlike, elastic 
fibres that we find in the walls of the arteries, etc.; secondly, a layer of a tissue 
consisting of smooth, long fibres crossing each other, and interwoven sometimes 
more regularly, as in the Trionychidae, or irregularly, as in Sphargis. According to 
the numerous sections which we have made, a deposition of lime generally takes place 
only in the elastic fibres, while the fibrous tissue lying beneath is resorbed. At least 
we find in all ossifications, when young, the arrangement of elastic fibres still very 
distinct; and Sphargis, in which a bony shield of about two lines in thickness 
begins immediately under the Malpighian layer, seems to show this particularly well. 
Under this follows a thick, coarse, fibrous tissue, in which there are no ossifications 
at all; under this, finally, follows the skeleton. In sections made in different direc- 
tions through the shield, we see clearly the character of the ossifications, as well as 
that of the skin which does not ossify, and that of the skeleton proper, which in 
most Turtles is very much affected by the ossification of the skin. A section 
through the soft but thick margin of the dorsal shield of Trionyx ferox, in which 
no ossifications take place, shows first a thin epidermis, then a thicker layer of 
elastic fibres, then many layers of fibres crossing each other regularly and producing 
by the regularity of their knees those seeming layers of the skin which are so strik- 
ing to the naked eye in any transverse section. Another section through a dermal 
ossification of the sternum of the same Turtle, shows the difference between the 
true skeleton bone, with its very regular structure, bone-holes, etc., and the dermal 
bone above it, in which many canals run through, piercing it in different directions, 
and in which the bone-holes also are more irregularly disposed, showing its origin 
from elastic fibres. This is still more evident in a section through a younger 
ossification in Chelonia Mydas, where the roundish or longitudinal holes of the 
elastic fibres are very distinct. Again, another section near the former, where the 
ossification has not yet begun, shows the character of the elastic tissue when it 
is about to be ossified. A horizontal section through the bony shield of Sphargis, 
which, as stated above, nowhere touches the bone, is also very characteristic. This 
structure furnishes of itself sufficient evidence of the incorrectness of the views 
which Cuvier1 and others entertained, that the whole bony shield of Turtles is pro- 
1 Without making any distinction between the 
dermal and the true skeleton, Cuvier (Lemons d'Ana- 
tomie comparee, 2d edit., vol. i., p. 2G3, and Osse- 
ments fossiles, vol. v., 2d part, p. 195), and with him 
also Geoffroy, (Mem. du Museum, vol. xiv.,) consider 
the carapace as formed entirely by the dilatation of 
the vertebras and the ribs. Carus (Urtheile, etc., p. 
150) was the first to show that a considerable portion 264 
AMERICAN TESTUDINATA. 
Part II. 
duced by a mere enlargement and overgrowing of the vertebra? and the ribs, that 
is to say, by the peculiar development of certain bones of the true skeleton. 
The bony shield of Sphargis exhibits, moreover, some peculiarities which we do 
not find in other Turtles. There is a most elegant pavement of small plates, 
extending over the whole shield, seemingly jointed to each other by the finest 
sutures, which, however, are in fact nothing but nutritive canals starting from those 
seeming sutures, themselves larger canals, and ramifying through the plates as a 
fine network of a yellow color, owing to the fat fluid which the canals contain. 
As I possess no young specimens of this Turtle, I have had no chance to observe 
the corium before it is ossified, so that this remains to be studied. The character of 
the ossification is, however, really the same as in the dermal ossification of Trionyx, 
mentioned above, except that the canals seem to be more regular in Sphargis. 
With reference to the extension of these ossifications, I have already made some 
remarks above, when speaking of the bony shield generally.1 I have now only 
to condense all the observations related above, in a few words. 
The ossifications of the corium in Turtles take place only in the dorsal and 
ventral walls of the body. Their development is greatest in land Turtles,2 and 
least in the Trionychidae and Sphargididae; in which latter, though they are relatively 
more extensive than in the Trionychidae, they yet nowhere reach the true skeleton. 
The deposition of lime in these ossifications is mostly so extensive, that they are 
just as hard as true bone, and in proportion to this deposition of lime, their 
structure approaches also more and more that of true bone, the holes of the 
elastic membrane appearing then as haversian canals, and around them the fine bone- 
holes, but it shows still everywhere its character as dermal bone by the irregularity 
of its structure. In order to ascertain what is true skeleton bone, and what dermal 
bone, I have availed myself not only of the difference in their structure, but resorted 
also to the investigation of the cartilaginous skeleton in the embryo, or in the young 
soon after hatching. Such young Turtles furnish, indeed, the most beautiful micro- 
scopical objects for the study of cartilage and its ossifications. Now wherever we 
find regular cartilage in the young, we take it for granted that such parts are to 
be considered as belonging to the true animal skeleton. Thus we have ascertained 
of the so-called skeleton of the Testudinata is formed 
by the skin. This has been further illustrated by W. 
Peters (Observationes ad Anatoniam Cheloniorum, 
Berolini, 1838) and by Owen (Observations on the 
Development of the Carapace and Plastron of the 
Chelonians, Philos. Trans., 1849, and Fossil Reptilia, 
Palaeontographical Society, 1849). The most strik- 
ing evidence of the independence of the dermal and 
the true skeleton is afforded by the solid frame of 
Trionyx, in which the growth of the dermal and of 
the true skeleton takes place by an alternate extension 
of their respective peripheric parts, as we shall see 
fully when considering this family more in detail. 
1 See, above, Sect. 4, p. 255-257. 
2 It is in this sense that the statement on page 
236, line 22, is to be understood. Chap. I. 
THE SKELETON. 
265 
that all the nine sternal bones of the Turtles are not mere dermal ossifications, as 
Rathke,1 misled by the attachment of the muscles inside, would suppose, but that they 
really belong to the skeleton, being regular cartilages with distinct forms, and of the 
same shape as the bones in the adult. In the same way we have ascertained that 
the marginal bones are mere ossifications of the skin, and by no means to be com- 
pared with the long bridges which connect the true ribs and the sternum in Birds, as 
Geoffroy, and after him, Dumeril and Bibron, believed.2 We found, farther, that 
that strange crosspiece, the foremost transverse bone in the carapace, is a regular 
skeleton bone, though I do not venture to call it either a rib or a transverse 
process of the last neck vertebra, as one might perhaps think it to be. There 
are limits to explaining and homologizing. We cannot make up a Bird from 
the bones of a Turtle, nor a Man from the bones of a Fish, as some anatomists 
have recently tried to do, who misunderstood the great thoughts of Oken and 
other philosophers respecting the structure of the skeleton. 
If we go back to the earliest stages of growth of the Testudinata to ascer- 
tain the true character of their bony shield, it will be easy to show that the 
bony walls which, in the adults, form the dorsal and pectoral shields, consist at 
first simply of cells, out of which the skeleton, the muscles, and the skin are 
formed in the end, in all Vertebrates, and that it is not the skin only which is 
here absorbed into the skeleton, but the whole animal wall. This view of the 
case may render more intelligible the apparently abnormal position of the limbs, 
and the mode of attachment of the pectoral muscles. 
SECTION VI. 
THE SKELETON. 
Head. The skull in the Turtles is more solid and compact than in the Saurians 
and Ophidians; the bones of the face, in particular, are immovably fixed to the 
skull-box; the os quadratum is also soldered to it by a tight suture as in Crocodiles 
and in Mammalia, while in the other Reptiles and in Birds it is jointed to the 
skull only by ligaments and a socket. The lower jaw is formed of one solid, 
bony arch, the soft symphysis between its branches having entirely disappeared 
as in Birds, while in Saurians this symphysis always remains more or less carti- 
1 See Rathke, Ueber die Entwickelung der Schild- 
krbten, p. 122. 
2 Geoffroy, in Annales du Museum, vol. xiv. 
Dumeril and Bibron, in Erp&ologie generale, vol. i. 266 
AMERICAN TESTUDINATA. 
Part II. 
laginous, and in the Ophidians it is so elastic as to allow the branches to move 
far apart one from the other. 
This solid conformation of the head shows, again, the high standing of the 
Testudinata, for the loose connection of the bones of the head is a character peculiar 
to Fishes, while the solid, compact skeleton of the head is characteristic of Mammalia. 
There is still another feature in the head of the Turtles which gives it a general 
interest: the great similarity of the hind part of the skull to a vertebra. The 
resemblance of the os occipitale basilare to the body of a backbone, and of the 
ossa occipitalia lateralia to an upper arch, is more striking than in any other Ver- 
tebrate. The bones around the brain are flattened; the parietal bones inclose 
the brain from above and from the sides, the wings of the sphenoid remaining 
relatively small. There are two pairs of frontal bones; the exterior ones are 
generally, though not always, united by a median suture, and cover the nasal 
cavity from behind. There are no nasal bones, except in one genus.1 In the 
fresh animal, the condylus occipitalis is a nearly round prominence with a depres- 
sion in the middle, in which the second vertebra articulates; when dry it is 
triangular. In the dry skull the composition of this condylus, formed from one 
basilar and two lateral occipital bones, is evident by the sutures. This structure is 
the same as in the true Saurians and Ophidians; but while in Turtles the second 
vertebra fits with its head into the pit in the middle of the condylus, in the 
Saurians and Ophidians, on the contrary, it rides upon a roundish excavation 
on the upper side of the condylus. Again, the Crocodiles differ from the three 
other orders of Reptiles by having their round condylus formed only from the 
os basilare. 
There are nine vertebrae of the neck, (not eight as is generally stated,) the 
second, the so-called odontoid process of the epistropheus, very clearly showing, in 
these Reptiles, its right to be considered as a distinct vertebra, as it remains separated 
from the epistropheus through life. There are no transverse processes in any 
vertebra of the neck. The upper arches are always soldered to the bodies of 
the vertebras by sutures. The articulation of these vertebras to each other is 
entirely peculiar to Turtles, there being some convex-concave, some concave-convex, 
one biconcave, (usually the eighth,) and one biconvex, (usually the fifth.) This 
configuration of the vertebrae gives fixity to certain bendings of the neck, thus 
depriving it of that flexibility which is characteristic of the neck of the Birds, 
while it is, at the same time, much more movable than the neck of any other 
order of Reptiles, or that of the lower Vertebrates. 
1 In Hydromedusa, nasal bones have been dis- 
covered by W. Peters, (Observationes ad anatomiam 
Cheloniorum, BeroL, 1838.) Whether this character 
is common to all Hydraspides, remains to be seen. Chap. I. 
THE SKELETON. 
267 
The vertebrae of the chest and abdomen are, as in Birds, soldered together 
into one inflexible and more or less convex arch, though there are still thin 
cartilaginous cushions between them. That connection is chiefly effected by the 
spinal processes, which grow continuously, without an intervening suture, into the 
ossified shield formed in the corium all over the back, thus forming a kind of 
framework for that superimposed roof. 
The ribs are fixed to the places where the vertebrae meet, but the vertebrae 
do not send out peculiar processes for their support. They are strongest in those 
Turtles in which the ossifications of the corium are least extensive, namely, in 
the Trionychidae, Sphargididae, and Chelonioidae; weaker in the Chelydroidae and 
Emydoidae; weakest, and indeed often disappearing entirely, in the land Turtles. 
The sternum consists of nine bones, four in pairs, one odd,1 all of which are 
true bones. Their relation to each other in size and connection varies greatly in 
different families. While in the land Turtles and Emydoidse they form one solid, 
continuous, broad shield, covering the whole chest and the abdominal region from 
below, they are much less developed in some of the Cinosternoidae, (Ozotheca, for 
instance,) and least in the Trionychidae, Chelonioidae, and Sphargididae. In all the 
three latter families, the bones of the sternum are very narrow, meeting each other 
by slender processes, leaving much room between them, which is filled out by the 
corium, thus forming a flat, elastic sternum.2 The sternum is jointed to the ribs 
by means of a bony bridge, which may be compared to the cartilaginous or bony 
bridge of other vertebrates, while the so-called marginal bones are mere ossifica- 
tions of the skin. 
The vertebrae of the tail are very movable, convex behind, concave before. 
No spinal processes either above or below. 
The locomotion in Turtles is entirely restricted to the four legs. The bones 
which are subservient to locomotion, appear entirely peculiar to this order of 
Reptiles, as far as their form and connection with each other, as well as their 
position with reference to the other parts of the skeleton, are concerned. 
The shoulder apparatus no longer rests upon the ribs as in the other Verte- 
brata, but lies in advance of the ribs, and is more or less withdrawn under them. 
The whole construction of these Reptiles shows the intention to cover all soft parts 
by a hard shield. This being the case, there is no room for a movable appa- 
ratus upon the ribs. As the shoulder apparatus with the humerus, so also is the 
1 This odd bone is wanting in the full-grown 
Cinosternoidae. 
2 It is for this reason, perhaps, that we do not 
find, in these three families, the sternum of the males 
scooped out, (to facilitate copulation,) as we find it 
generally, though not always, in land and marsh 
Turtles. In Sphargididae the sternum is reduced 
to a bony ring, consisting of slender pieces, and the 
disc inclosed by it is mere corium. The odd bone 
seems to be wanting. 268 
AMERICAN TESTUDINATA. 
Part II. 
pelvis with the femur, withdrawn under that large bony roof, though the ribs do 
not extend over the pelvis as they do really over the whole shoulder apparatus. 
As we have already seen, in the preceding section, that this bony roof is formed 
of the ossification of the skin, it is plain that the position of the four limbs, 
below its spreading margins, does not alter their homologies, and that on the 
whole the locomotive members occupy here, as in all quadrupeds, a normal posi- 
tion upon the sides of the backbone, and that they are as usual protected by 
the general covering of the body, only that here this outer envelope is ossified. 
It follows, therefore, that Testudinata cannot form a class by themselves. The 
shoulder is composed of three narrow bones, rather long and straight, meeting in 
one point, and forming at their junction the cavitas glenoidalis for the humerus. 
Two of these bones, soldered together at right angles1 as one bone, represent, 
the upper one, the scapula, the lower, the furcula of the Birds;2 the third bone, 
running backwards, answers to that bone in Birds which, coming from the scapula, 
rests in a deep, transverse socket of the sternum. Merely to use names already 
adopted, and without intending to homologize these bones beyond the limits here 
alluded to, we shall call the first, scapula, the second, acromion, and the third, 
coracoid process. The scapula, a long, cylindrical bone, is attached by a ligament 
to the dorsal column just before the first (rudimentary) rib ; the acromion, a shorter, 
somewhat flattened bone, is attached to the sternum by syndesmose just before the 
odd bone. The coracoid process runs backward and hangs free between its mus- 
cles; its broad, flattened posterior end, and the end of the acromion, are connected 
by a strong ligament. This coracoid corresponds in its form and in its relations 
to the other bones of the shoulder apparatus, though not in its attachment to 
the coracoid of the Saurians, the Crocodiles, and the Birds, in all of which its 
1 There is only one exception known to this gen- 
eral rule. In a skeleton of a North American Emys, 
in the Anatomical Museum of Berlin, there is on one 
side of the animal a suture between these two bones. 
See Stannius, Handbuch der Zootomie, I., 2d edit., 
p. 75, note. 
2 There has been much diversity of opinion about 
the homology of the three bones of the shoulder 
apparatus of the Turtles, and the two or three bones 
which we find in their place in other Vertebrata. 
Bojanus, in his great work, Anatome Testudinis Eu- 
ro paeaj, Vilnae, 1819, at first mistook the coracoid for 
the scapula, and called clavicula the scapula, together 
with the acromion (see Pl. viii., 0 and N) ; but he 
soon afterwards corrected himself in the Isis. Cuvier, 
and most anatomists now living, Stannius, among them, 
in the second edition of his Handbook, have named 
these bones as we do, while in his first edition, p. 139, 
Stannius called the acromion, clavicula. Dumeril 
and Bibron (Erpetologie generale, I., p. 382) call the 
coracoid, clavicula. We see here that for each bone 
nearly all possible homologies have been supported 
by some writer or other. This seems to show that 
there are limits to homologizing. Though we are 
persuaded that these bones of the Turtles are homol- 
ogous to those of the Birds in the manner in which 
we have referred them, one to the other; yet we do. 
not dare to go farther, and homologize them at the 
same time with the bones of the shoulder in Mamma- 
lia, and still less with the thoracic arch of Fishes. Chap. I. 
THE SKELETON. 
269 
lower encl rests in a socket, in the foremost part of the sternum; but in Turtles 
the whole shoulder apparatus being drawn inwards and backwards, this bone had 
to be removed from the sternum, and lies free in the muscles. 
The humerus is short, crooked, and turned inwards in such a way that it 
moves inwards in one plane with the scapula and coracoid. The forearm is articu- 
lated upon the large lower epiphysis of the humerus, but its position is peculiar 
to the Turtles, its transverse diameter standing vertically. This is effected by an 
overlying of the fibula upon the radius. In the structure of the hand, we find 
again, in the same manner as in the forearm, the transverse diameter standing ver- 
tically, the ulnar side above, the radial side below. This singular conformation of the 
shoulder, the arm, the forearm, and the hand, makes it possible for the fore leg to be 
drawn back under the upper shield by the bending of all the joints in the plane 
of the scapula. This motion is more or less extensive in different families, accord- 
ing to the degree of expansion of the carapace. 
The conformation of the hand varies much in different families, according to its 
function as a paddle, as a fin, or as a pillar.1 
The pelvis is much easier to understand than the shoulder. It is formed, on 
each side, by three permanently distinct bones, meeting in the condyloid cavity. 
Two pairs of these bones are flat and more or less horizontal, and rest upon the 
sternum, to which they are more or less closely attached. The larger pair, the 
ossa pubis, leans forwards, the smaller pair, the ossa ischii, backwards. The 
bones of each pair unite respectively with one another in the middle, in a 
median line, while the two bones of the same side, meeting laterally, form the 
lower part of the cavity for the femur. The upper part of this cavity is formed 
by the third pair of the pelvic bones, the ossa ilii; these are smaller cylindrical 
bones, much enlarged at both ends, running upwards and backwards, and meeting 
with the long transverse processes of the sacrum. 
The bones of the hind leg agree generally with those of the fore leg, though 
the femur is straighter than the humerus. There are, however, great differences 
in different families, in respect to the relative size of the two pairs of the legs. 
These differences are so strongly marked between the marine Testudinata on one 
side, and the fluviatile and terrestrial types of the order on the other side, that 
they cannot be considered as family characters, but rather point out a natural 
subdivision of the whole group, already hinted at above,2 and to which I shall 
again call attention hereafter. 
1 See the Family Characters, below, Chap. 2. 
2 See, above, Sect. 2, p. 241-249. 270 
AMERICAN TESTUDINATA. 
Part II. 
SECTION VII. 
MUSCLES. 
The ordinal characters of the Turtles, as far as the muscles1 are concerned, 
are particularly obvious in the muscles of the neck and in those of the region 
of the trunk. That bulk of muscles which in Ophidians and Saurians lies above 
and below the vertebral column and the ribs has almost entirely disappeared, 
owing to the immovability of the trunk.2 There exist only two muscles along 
the back of the Turtle, and even these disappear in that family, which is char- 
acteristic of the highest development of the order, in the land Turtles. These 
muscles are, a musculus longissimus dorsi and a M. retrahens capitis collique, both 
originating from the dorsal column or its neighborhood, and attached to the neck 
or to the head; so that, properly speaking, even these are more muscles of the 
neck than of the trunk. 
The musculus longissimus dorsi3 runs along the back on both sides of the 
vertebra), between the ossified corium and the ribs. It originates from about 
the eighth or ninth to the fourth or third rib and the dorsal shield of that 
neighborhood, and is attached to the last or to the two last vertebra) of the neck. 
It is very large and powerful in the family of the Snapping-Turtles, (Chelydroidae,) 
the arches through which it passes being here high and broad. This passage is 
much narrower in the family of the Emydoida), and the muscle also much weaker; 
in Cistudo virginea, the highest of the Emydoida) and the nearest to the land 
Turtles, we see it developed only in the anterior part of the trunk, until in the 
land Turtles it disappears entirely. Even the arches through which it passes in 
other Turtles disappear in consequence of the resorption of the ribs which takes 
1 For further details respecting the muscular 
system, see Bojanus, Anatome Testudinis Europe®, 
Vilme, 1819-21, 1st vol. For a comprehensive 
abstract of what is now known respecting the mus- 
cular apparatus of all Turtles, see the valuable 
work of Stannius, Zootomie der Wirbelthiere, 2d 
edit., Berlin, 185G. 
2 A distinct muscular layer above the ribs, and 
distinct musculi intercostales, are only to be found 
in very young Turtles, in embryos, or in specimens 
recently hatched. I have seen these muscles most 
distinctly in the young Chelydra serpentina and in 
Trionyx ferox. See also Rathke, (R.,) Ueber die 
Entwickelung der Schildkroten, p. 155. 
8 In Emys serrata, Lesueurii, and geographiea, 
this muscle is much smaller than in E. Europsea, as it 
has been described by Bojanus. In Emys concentrica, 
it is the same as in the European species. But in 
Chelydra serpentina this muscle is very powerful, 
and the arches, near the dorsal column, through which 
it passes, are very large and high. In Chelonia 
Mydas, it is small. In Cistudo, we find it only 
in the anterior part of the dorsal column, and in 
Testudo there is no trace of it. Chap. I. 
THE MUSCLES. 
271 
place in this family in proportion as the ossification of the skin advances. This 
is the muscle above the ribs. 
The second muscle, the M. retrahens capitis collique, is below the ribs. This 
muscle is peculiar to the Turtles, the conditions of its existence being a solid 
trunk and a very movable neck. It originates from the bodies of all or most 
vertebrae of the trunk, and is attached to the articulating processes of the vertebrae 
of the neck and to the occiput. In some Turtles, it would be better to consider 
it as divided into two distinct muscles,1 as its action is not always simultaneous. 
1 Bojanus has described these muscles as one, 
in accordance with the subject of his investigations, 
the Emys europaea, in which the division into two 
muscles is much less marked than in many other 
genera, Ozotheca, for instance. In Emys serrata, we 
find it as in Emys europaea. In Emys concentriea, 
the muscle is one, originating from the eighth to the 
sixth dorsal vertebra, and attached from the sixth 
to the fourth neck vertebra । and with a long tendon 
to the occiput. In Emys geographica and Lesueurii, 
it is the same. In Cistudo virginea, it arises from 
between the ribs near the tenth to the second dorsal 
vertebra to the seventh and fifth neck vertebrae and 
the occiput. In Ozotheca odorata, we see distinctly 
two muscles. One of them, the M. retrahens colli in- 
ferioris, originates on each side of the dorsal column 
from the base of the third to the fifth rib, and is 
attached laterally to the penultimate (eighth) vertebra 
of the neck. This muscle draws the lowest part of 
the neck backwards and upwards. The other, the M. 
retrahens capitis collique superioris, originating from 
the bases of the fifth to the seventh ribs, is attached 
with one tendon to the uppermost part of the sixth 
neck vertebra, with another to the occiput. This 
muscle draws the uppermost part of the neck and the 
head backwards. When Ozotheca retracts its large 
head, which it does faster than any other Turtle, 
both muscles first operate simultaneously, but soon 
the short M. retrahens colli inferioris is entirely 
contracted, while the other is drawing further. 
Beyond these two muscles, we find in this genus a 
third muscle much developed, which serves the same 
purpose. The M. lateralis retrahens ultimas verte- 
brae colli, originating from the base of the second 
rib and the space between this and the third, and 
attached to the uppermost lateral part of the last 
(ninth) neck vertebra. This muscle is strong also 
in Cistudo virginea, where, however, it originates 
only from the base of the second rib. In our Green 
Turtle, (Chelonia Mydas,) we find a distinct though 
weak M. retrahens colli inferioris from the first dorsal 
to the last neck vertebra, while the M. retrahens 
capitis collique superioris is entirely wanting. But 
at the same time, it is well known, that in this family 
the power of retracting the head and the extremities 
under the shield is very much reduced, indeed, almost 
entirely wanting. On the contrary, in Testudo 
tabulata these muscles are very strong. The M. 
retrahens capitis collique superioris originates from 
the seventh dorsal to the first sacral vertebra, and is 
attached from the third to the fifth neck vertebra and 
the occiput; the M. retrahens colli inferioris, from 
the first to the sixth dorsal vertebra, and from the 
sixth to the ninth neck vertebra. Thus, both these 
muscles occupy the dorsal column from the head to the 
sacrum. In these land Turtles we observe, indeed, 
the other extreme of what we have noticed in the sea 
Turtles, as in them all structural elements are em- 
ployed for the purpose of covering all the soft parts 
by a thick, large shield, under which they are 
retracted. In Chelydra serpentina, we may consider 
these muscles as one, originating from near the tenth 
to the fourth dorsal vertebra, (rather from the bases 
of the ribs in this region,) and attached to the eighth 
and seventh neck vertebrae, and with a long tendon 
to the occiput. In this family, however, this muscle 
is not developed in the same degree as the remaining 
muscular system, and particularly that of the legs 
and tail, which is truly extraordinary, and aids in 
the peculiar darting motions of the body. 272 
AMERICAN TESTUDINATA. 
Part II. 
The first of these is a very long muscle, originating from the posterior vertebra 
of the trunk, and attached to the foremost neck vertebra and the head. Its 
function is to draw back the head and the uppermost part of the neck, so that 
we . may call it musculus retrahens capitis collique superioris. The second muscle 
is much shorter, originating from the anterior vertebrae of the trunk, and attached 
to the lower part of the neck. It lies below the first, and its function is to 
draw the lower part of the neck backwards. We may call this muscle M. retrahens 
colli inferioris. The form into which the neck is thus contracted is that of an 
S in a vertical plane. I regret deeply that I have not had an opportunity of 
examining the arrangement of the muscles of those Turtles which bend the neck 
sideways and fold it under the margin of the shield, as do the Chelyoidae and 
Hydraspides. 
Considering now the cervical muscles proper, we find a system of shorter 
muscles largely developed, running from one vertebra to the next or to the 
next but one. These muscles are particularly subservient to stretching the neck 
into a straight line, when it has been bent by the muscles described above, and 
thus to dart it forwards, as all Turtles do more or less rapidly. This action is, 
however, peculiar and very quick and powerful in the families of Chelydroidaj 
and Cinosternoidae. 
The posterior part of the dorsal column, with its free vertebra? between the 
sacrum, the anus, and the tail, is also provided, like the free movable neck, with 
a well developed muscular apparatus, which is particularly powerful in Chelydra. 
The muscles which move this part originate from the three pairs of pelvic 
bones. 
The muscles of the shoulder and of the pelvis, which are all inside the bony 
box, are very difficult to homologize with those which we find in other Reptiles or 
in other Vertebrata. Two pairs of muscles, originating from the hind part of the 
plastron and attached to the ossa ischii and pubis, draw the pelvis, the first back- 
wards, the second forwards. Stannius mentions traces of Musculi recti in some 
Turtles, originating from the anterior ventral part of the pelvis. Musculi obliqui 
externi and interni are obvious in almost all Turtles. The obliqui externi are 
particularly developed. Originating from the inside of the marginal bones of the 
dermal shield, they are attached to the os pubis. 
The muscles for the shoulder are not much developed in comparison with 
those of the Saurians or Birds, in which the shoulder lies free on the outside of 
the ribs. There is one muscle in Turtles drawing the scapula forward, the M. 
scalenus or levator scapulae of Bojanus, originating from the lower part of the 
vertebrae of the neck and attached to the acromion; and another, originating from 
that large crosspiece mentioned above, p. 265, (which may be looked upon as a Chap. I. 
THE MUSCLES. 
273 
processus transversus, or as a first rudimentary rib,) and from the dorsal shield 
in its neighborhood, going to the scapula and drawing it backwards. This muscle 
is the M. subclavius or retractor scapulae of Bojanus. A third muscle is extended 
between the tongue-bone and the coracoid, the M. coracohyoideus. Besides this 
muscle, which originates from the lower side of the bony framework of the tongue- 
bone, we find for the tongue two other pairs of muscles, the musculi hyothyreoidei 
and the musculi cricoarytmnoidei. 
The muscular apparatus of the extremities is remarkable for its similarity to 
that of Mammalia.1 In place of the M. pectoralis major, we find two muscles, 
one originating from the middle part of the sternum and attached to the tuberosity 
of the humerus, whence it spreads downwards over the arm and the forearm, and 
another, much weaker, arising from the anterior part of the sternum and attached to 
the same internal tuberosity. The deltoid muscle originates from the end of the 
acromion and goes to the same tubercle. The muscles arising from the scapula, 
the M. subscapularis and the M. teres, are both attached to or near the tuberculum 
externum. A muscle corresponding to the M. latissimus dorsi, arising from the 
exterior lateral part of the dorsal shield, is attached to a little cavity inside of 
the tuberculum externum. The M. coracobrachialis, arising from the coracoid and 
attached to the tuberculum externum of the humerus, is simple in the family of 
Emydoidm, and double, as in Mammalia, in the Trionychidae. The muscles of the 
forearm, and those of the hand and fingers, are essentially identical with those of 
the Saurians; the degree of development of the muscular apparatus of the hand and 
fingers varies much, however, in different families. They are much less developed 
in the sea and land Turtles than in the webfooted Emydoidae, Cinosternoidae, 
Chelydroidae, and Trionychidae. The characteristic muscles of the hind extremities 
are the following: two musculi glutaei, (a major and a minor,) originating from 
the os ilii and from the seventh rib. Forming at first one muscle, they are soon 
divided into two branches, one of which is attached to the trochanter, the other 
to the femur itself. The M. biceps, originating from the os ilii, is inserted upon 
the fibula. The M. psoas, originating from the last vertebra of the back, before 
the sacrum, is attached to the upper part of the femur. The Musculi adductores 
femoris originate, one from the symphysis ischiadica, another from the os pubis, 
and a 'third from the membrana obturatoria and from the anterior margin of the 
os ischii. 
1 Its development, however, is very different 
in different families. The fore legs and the hind 
legs have an equally strong muscular apparatus in 
land Turtles, where the whole body stands in equi- 
librium; while in sea Turtles, in which the fore 
legs are the chief locomotive organs while the hind 
legs serve almost only as rudders, the fore legs 
have a much larger muscular development. 274 
AMERICAN TESTUDINATA. 
Part II. 
SECTION VIII. 
NERVOUS SYSTEM. 
With reference to the brain, we may single out as characteristic of the Testudi- 
nata the well developed hollow hemispheres, which are larger in proportion than 
in other Reptiles, especially when compared to the lobi optici. Their surface is 
generally smooth, but in some it is provided with a longitudinal fold. Their 
cavities are continued into the hollow roots of the olfactory nerves. The cere- 
bellum is relatively larger than in Ophidians and Saurians, yet smaller than in 
Crocodiles. A longitudinal furrow divides it into halves. Between the two hollow 
lobi optici and the hemispheres, there are two lobi ventriculi tertii, which give rise 
to the optic nerves. Behind the large cerebellum follows a large vascular body, 
(plexus chorioideus,) which lies upon the sinus medullae ablongataa.1 
In relation to the nerves that originate from the brain and the medulla 
ablongata, we notice that, as in Ophidians and Saurians, the nervus hypoglossus 
receives roots from the spinal marrow, which is not the case in Crocodiles. As 
in Saurians and Ophidians, the nervus vagus and the glossopharyngeus have always 
each a root for itself, and, as in Saurians, each also a distinct passage through 
the os occipitale laterale; while in Ophidians there is only one passage, and in 
Crocodiles, with some exceptions, only one common root for both those nerves, 
which thus form also only one common ganglion. As in all Reptiles, the largest 
nerve is the nervus trigeminus; it is larger even than the nervus vagus, though 
this latter is more developed in Turtles than in other Reptiles. 
The spinal marrow is rather thin along the middle of the body; and the nerves 
which originate in this region are very small, as there is not much room for 
their function, in consequence of the immovability of that part of the trunk which 
corresponds to the shield, and which moreover is covered by a thick, hard, horny 
roof. So much the larger, however, appear the two swellings of the spinal marrow 
in the shoulder and pelvis region, where the legs, which in this order of Reptiles 
have to support and to move the whole body, are to be provided with nerves. 
Thus the size of these swellings, when compared with the general diameter of the 
spinal marrow, is characteristic of the Testudinata, and more resembles that of 
1 Foi' the differences of the brain in different 
families, see below under the head of The Family 
Characters. A beautiful illustration of the brain and 
the whole nervous system of the European Emys has 
been given by Bojanus, in his Anatome Testudinis 
Europaeae, PL xxi.-xxiii. Chap. I. 
ORGANS OF SENSES. 
275 
Birds than of other Reptiles, in which latter the organs of locomotion are never 
confined to the legs alone. See above, p. 253. 
The characteristic features of the N. sympathicus1 are only to be appreciated 
by a minute comparison of all its original roots, anastomoses, ganglia, etc., with 
those of Crocodiles, Lizards, and Snakes. But, though there are many differences 
in its conformation in these different orders of Reptiles, we do not deem it 
necessary or useful to enter into the details of such a comparison; in the first 
place, because only some two or three species of Turtles have as yet been inves- 
tigated with special reference to that nerve, so that there would be danger of 
confounding ordinal with family or even generic characters; and in the second 
place, because the differences which we have noticed do not show an inti- 
mate connection with the whole nature of the Turtles, in contradistinction to 
other Reptiles. It is, moreover, proper that in Comparative Zoology we should 
introduce only such anatomical characters as are understood in their connection 
with the whole nature of the animals under consideration. Other anatomical 
details would be useless for the zoologist. 
SECTION IX. 
ORGANS OF SENSES. 
The Ear. There is no movable external ear as in the Crocodiles; but in all 
Testudinata we find a cavitas tympani and a membrana tympani, which are wanting 
1 The N. sympathicus begins in Turtles as plexus 
sphenoideus, and is connected with the second branch 
of the N. trigeminus. It runs as a simple trunk back- 
wards, gives branches to the nose, and receives 
branches from the N. abducens facialis; then after 
passing through the os petrosum as N. Vidianus it 
receives branches from the N. facialis and glosso- 
pharyngeus, then from the N. vagus and hypoglossus, 
and then runs as one superficial stem along the neck 
to the thorax, connected by branches with the nerves 
of the neck. Then taking up branches of the vagus, 
it forms the ganglion thoracicum primum, which 
sends its threads to the plexus cardianus and pul- 
monalis. Then the string forms several swellings, 
connected with the plexus brachialis, forming several 
loops which unite again into ganglia and communi 
cate with the anterior branches of the spinal nerves. 
Then after giving branches which go to the inter- 
costal nerves, it forms again two plexus, the first 
sending branches to the stomach, and accompanying 
the arteria cceliaca; from the second plexus originate 
branches for the intestines, and others for the kidneys 
and the generative organs. See Stannius, Lehrbuch 
der Vergleichenden Anatomie der Wirbelthiere, Ber- 
lin, 1846, p. 192-93; Bojanus, Anatome Testudinis 
Europaeae, Pl. xxii. and xxiii.; and Swan, Illustra- 
tions of the Comparative Anatomy of the Nervous 
System, London, 1841, Pl. xv. and xvi. 276 
AMERICAN TESTUDINATA. 
Part II. 
in Saurians.1 The helix is a simple, round, membranous sac, with a closed fenestra 
rotunda, and a communication with the saccus vestibuli by means of a membra- 
nous canal. A very long columella is attached to the fenestra ovalis, which itself 
is closed by an opercle. The cavitas tympani is divided into two parts by a 
bony septum. The tunica tympani is only attached to the os quadratum. Between 
the two lamellae of this membrane lies a cartilaginous plate, into which the colu- 
mella is inserted. 
The Eye. This organ is larger in proportion and more movable in Turtles 
than in other Reptiles.2 We find in the constitution of this organ a great similarity 
with Birds. Not only are the protecting membranes of the eyeball in Turtles and 
Lizards, in contradistinction to Snakes, very much as in Birds, there being two 
eyelids and a membrana nictitans, but we find in Turtles also the same bony 
framework in the cornea as in Birds. This bony ring has been erroneously ascribed 
also to Crocodiles.3 It does not exist either in these, or in Ophidians, or in Sauri- 
ans,' but singularly enough we find it again in all those huge Reptiles of past ages 
known as Plesiosauri and Ichthyosauri. The iris of Turtles is always colored, gen- 
erally dark, but in some red, or even milk-white. We see, however, that this color 
varies much in one and the same species, as, for instance, in Cistudo virginea, in 
Ptychemys concinna, etc. The form of the pupil, which is vertical and elliptical in 
many Snakes and Saurians and in all Crocodiles, is round in all Turtles, as it is in 
Birds. There is, however, no pecten in the vitreous body, as in all Birds and in 
many Saurians; the vitreous body itself is very large. In the orbita we find two 
well developed glands, namely, a lachrymal gland above the bulbus, and another, a 
Harderian gland, behind and inside. 
The Nose. While the sense of seeing, and particularly that of hearing is 
highly developed in Turtles, the sense of smelling is much less so; and while the 
former two senses exhibit in them a degree of perfection which we find elsewhere 
only in warm-blooded animals, Turtles do not at all stand above the level of other 
Reptiles with respect to the latter sense. In explanation of this we may perhaps 
say that the slow rhythm of the respiration, which is common to all four orders 
of Reptiles, does not facilitate the admission of odoriferous materials into the nose, 
and that it is for this reason that we find the nerves and bones of this organ 
1 In Dum^ril et Bibron, Erpdtologie generale, 
vol. i., p. 399, this membrane is erroneously said not 
to exist in Turtles. 
2 There is one single exception to this statement; 
in the South-American Matamata, (Chelys fimbri- 
ata,) the eyes are remarkably small. This Tur- 
tle, however, so peculiar also in other respects, and 
particularly in the structure of its head, forms un- 
questionably a family for itself. 
8 Already Soemmering, and later, Rymer Jones, in 
Todd's Encyclopaedia of Anatomy and Physiology, 
vol. iv., p. 314, have made this statement, which we 
must deny, in accordance with the observations of 
Tiedemann, Stannius, and our own. Chap. I. 
ORGANS OF SENSES. 
277 
so little developed. The cavity of the nose is wide, but short. There are no 
sinus frontales, nor lamina cribrosa, nor bony concha, nor even nasal bones.1 The 
concha is cartilaginous. The nervus olfactorius is characterized by two tubercles at 
its base, just in advance of the hemispheres; it has, in this respect, a strange simi- 
larity with that of Frogs. The nostrils are always situated in the topmost part of 
the snout; they seem particularly subservient to breathing, in water Turtles at least. 
Thus I have frequently seen Trionyx ferox lying for hours in shallow water, 
buried in mud, and stretching only, from time to time, the nostrils above the 
level of the water to breathe. The South-American Matamata is said to await 
its prey in a similar situation, hid among the leaves of water plants, exhibiting 
nothing above the water but the nostrils, which are elongated and tube-like, as 
in Trionychidae. The marine Turtles also come from time to time to the surface 
for the sake of breathing. 
The Tongue and Mouth. In all Ophidians and Saurians, as in most Birds, the 
tongue is only an organ of touch; in most of these animals it is long, slender, 
covered with horn, and may be more or less protruded from the mouth for that 
object. This is by no means so with the tongue of Turtles. It is broad, thick, 
fleshy, generally folded, mucous, and in one family (the land Turtles) even thickly 
provided with papillae, like the tongue of a parrot. Turtles chew their food, partic- 
ularly the herbivorous land Turtles, while other Reptiles swallow it without chew- 
ing. Thus the organ of taste is very much developed. Not only the tongue, but 
in some, as for instance in Trionyx, the whole pharynx is beautifully fringed 
with fine, tree-like, branching papillm,2 while in Chelonioidae we find long, strong, 
and hard papillae, extending even into the oesophagus. The papillae of the latter 
seem, however, from their hardness, more subservient to the motion of the food 
than to tasting. But tasting is by no means the only function of the tongue. 
Filling out the whole cavity of the mouth, it has also another function in the 
process of breathing, as it has also in Frogs, for Turtles swallow the air they 
breathe. (See, below, p. 281.) In all Turtles we find salivary glands. 
Organ of Touch. There is no special organ for this sense to be found in Turtles. 
1 Comp. p. 30, respecting Uydromedusa, which 
forms an exception, as it has nasal bones. 
2 Comp. Dr. A. Sager's Notes on the Anatomy of 
the Gymnopus spinifer of Dumeril and Bibron. 278 
AMERICAN TESTUDINATA. 
Part II. 
SECTION X. 
EATING, DRINKING, AND DIGESTIVE APPARATUS. 
Ill describing the skin, we have already mentioned the characteristic horny 
sheath of the jaws, which forms a bill such as we find only in Birds besides. 
The upper jaw always includes the lower, as it reaches beyond this. Generally, the 
horny sheath which covers the jaws runs more or less inwards into the mouth; 
in the Chelonioidte, it forms even several ridges parallel to the margin of the jaw, 
evidently for crushing and breaking the thick sea-weeds, upon which they feed. 
As all other Reptiles have true teeth and no horny cover whatsoever on the 
maxillar bones, this sheath is peculiar to the order of Testudinata;1 and while all 
other Reptiles use their jaws merely for seizing their food, Turtles, on the contrary, 
chew it. This is particularly the case with the herbivorous families, Chelonia and 
Testudo. A much more extensive use of the tongue is connected with the act of 
chewing, as long as the food is in the mouth, than we observe in other Reptiles. 
Thus the fleshy tongue of the Turtles serves three different purposes: first, in 
tasting, (see p. 277,) then in the act of respiration, (see p. 281,) and thirdly, in 
managing the food as long as it is in the mouth; that is, for bringing it into 
the right position between the sharp scissors formed by the bill, and for moving 
it into the pharynx and oesophagus when it is sufficiently divided. The last two 
uses of the tongue are the more interesting, as we do not meet them again, 
to this extent, except in Mammalia. The tractus intestinalis has generally thick 
walls. The oesophagus of the family of Chelonidse is provided with long, hard 
papillae. The stomach lies always transversely, crossing the body from the left to 
the right. The length of the whole intestine, in comparison with the length of the 
trunk of the animal, varies very much in different families, being longer in the 
herbivorous, and shorter in the carnivorous Turtles, just as among Mammalia and 
Birds. The relative length of the different parts of the intestine, compared with 
each other, varies still more; the rectum being very short in Emydoidae, Cinoster- 
1 Yet the order of Turtles is not the first among 
Vertebrates, in which we find the jaws transformed 
into a bill. We find already something similar 
among the Fishes, in the so-called Parrot Fishes, 
(Scarus,) and again among Amphibia, in the larvae 
of the Batrachia anura. I may add, however, that 
after removing the horny sheath, we find, along the 
dental ridges of the jaws, in the young Trionyx and 
Chelydra, a regular series of holes for nerves, which 
are evidently homologous to the alveola) of the teeth 
in other Reptiles. These holes contain, however, no 
rudimentary teeth, as are found in the jaws of Whales. Chap. I. 
DIGESTIVE APPARATUS. 
279 
noidae, Chelydroidae, and Trionychidae, and very long in land Turtles and in Chelo- 
nioidae. Our observations show this variation to extend to such a degree that we 
are unable to obtain from this part of the organization of the Testudinata an 
ordinal character, in contradistinction from the other Reptiles, as the following table 
satisfactorily proves.1 
Family. 
Species. 
Total 
weight of 
the body in 
ounces. 
Length 
of the 
Carapace 
in inches. 
Total 
length of 
the diges- 
tive duct. 
(Esopha- 
gus. 
Stomach. 
Small 
intestine. 
Coecum. 
Large 
intestine. 
Cloaca. 
Land Turtles, 
(herbivorous.) 
Testudo polyphe- 
mus, fem. 
100 
101 
821 
4f 
81 
i 
44| 
31 
Land Emydoidae, 
(omnivorous.) 
Cistudo, triunguis, 
(3 toed Box-tur- 
tle,) fem. 
15 
51 
31 
3 
31 
19f 
f 
51 
Water Emydoidae, 
(omnivorous.) 
Emys rugosa, (ru- 
briventris,) fem. 
62 
11 
99 
5 
7i 
70f 
i 
13 
31 
Cinosternoidae, 
(carnivorous.) 
Cinosternon penn- 
sylvanicum, fem. 
«* 
41 
*2 
24| 
CO 
21 
161 
0 
21 
Chelydroidae, 
(carnivorous.) 
Chelydra serpen- 
tina, male. 
65 
101 
801 
10 
71 
48f 
0 
111 
31 
Trionychidae, 
(carnivorous.) 
Trionyx ferox, 
fem. 
76 
13 
581 
6 
6 
35 
0 
6 
51 
Chelonioidae,2 
(herbivorous.) 
Chelonia Caouana. 
77 
102 
1 These measurements may be of interest, as they 
were made upon fresh specimens. The numbers, 
which express the length of the parts in the table, in- 
dicate American inches, twelve of which make one 
foot; the weight of the body is given in officinal 
ounces, twelve of which make a pound, and one of 
which is equal to 480 grains. In this table, which 
explains itself, we will only point out Cistudo, which, 
upon a superficial examination of its outlines, would 
seem to belong to the Testudinina, (land Turtles,) 
and which, by the proportions of the different parts 
of its intestines, is in reality an Emydian, as it will 
be shown below from a critical examination of its 
forms. See The Family Characters, below. 
2 This last measure, respecting Chelonia Caouana, 
is borrowed from the valuable Chemical and Physio- 
logical Investigations by Joseph Jones, published in 
the Smithsonian Contributions to Knowledge, vol. 
viii., 1856, where the student will find many interest- 
ing data relating to the digestion of Turtles in com- 
parison with other cold blooded, and with warm blood- 
ed animals. 280 
AMERICAN TESTUDINATA. 
Part II. 
The whole tract of the alimentary canal is provided with folds, between which 
there are everywhere crypts from the stomach to the anus. The coecuin is small, 
or wanting. A large, broad liver, continuous from one side of the body to the 
other, by means of a bridge, receives the heart in front between its two halves. 
A large gall-bladder is imbedded on the right side. The spleen and the pancreas 
are never wanting; the spleen is generally attached to the pancreas, and this to 
the duodenum. The spleen is an ovoid, or globular, solid body, while the pan- 
creas is more or less divided into lobes, often broadly and thinly scattered, par- 
ticularly in the herbivorous Turtles, and, on the whole, of a very irregular shape. 
As among Mammalia, so among Turtles, the pancreas is generally much larger in 
the carnivorous families than in the herbivorous, having, for instance, in the her- 
bivorous Testudo polyphemus only about the weight of the body, while in 
Emys serrata, which feeds upon fishes, mollusks, and worms, etc., about and 
in Chelonura serpentina, which is entirely carnivorous, even But, as a strange 
exception, we see in the herbivorous Chelonia Caouana the number All Turtles 
digest rather slowly, particularly the herbivorous land Turtles, which keep always 
a store of half-digested vegetables in their enormously large intestine. Turtles stand 
hunger for several months; Emyds, if they are provided with water, for more than a 
year. All Turtles which we had an opportunity to observe, when drinking, held the 
head under the level of the water, and evidently swallowed the water. The Gala- 
pagos land Turtles, (Testudo indica,) however, are said to drink like most Birds, 
by taking a mouth full of water, and then holding up the head and neck ver- 
tically, letting the water run down through the oesophagus. Turtles, (particularly 
the land and fresh-water Turtles,) like Frogs, usually carry with themselves a 
quantity of water in the cloaca. According to recent observations of Professor 
J. Wyman, this water is taken up through the anus. 
1 See Jos. Jones, 1. c.^ p. 107, where a list is given 
containing the weight of the pancreas in proportion to 
the body for several Fishes, Amphibians, Reptiles, 
and Mammalia. For the Loggerhead-Turtle, (Che- 
Ionia Caouana,) which J. Jones has numbered among 
the carnivorous Reptiles, we have to remark, that as 
far as we know it feeds, like the other Chelonioidae, 
upon sea-weed. If this be true, the law given by J. 
Jones, in relation to the proportionate size of the 
pancreas, (1. c., p. 108,) is evidently not without ex- 
ceptions, and it shows also how careful we must be in 
drawing such broad conclusions. Chap. I. 
RESPIRATION. 
281 
SECTION XI. 
RESPIRATION. 
Here, again, we meet with a very striking ordinal character. The Turtles 
swallow the air they breathe.1 The breast-box, which includes the lungs, being 
immovable, a respiration like that of the other Reptiles, the Birds, and Mammalia, 
performed by the expansion and compression of the breast-box, and consequently 
of the lungs, is impossible. Owing to the peculiar structure of their trunk, breath- 
ing is, therefore, only possible for Turtles by a pressure of the air from the 
mouth down into the lungs; but, though we are persuaded that this swallowing 
of the air constitutes the main act in the process of breathing, still we are inclined 
to believe, against the opinion of other anatomists, that the diaphragm, which in 
Turtles is very much developed, and attached to the lungs, takes also its part 
in that act.2 Moreover, the muscles of the shoulder and of the pelvic region may 
assist in that operation, either by immediately compressing the lungs, which generally 
extend in Turtles from one end of the trunk to the other, or by pressing the 
bowels against them. 
The act of swallowing the air is chiefly performed by the apparatus of the 
tongue-bone, and the tongue itself, which, by its large size, facilitates the opera- 
tion. Being drawn backwards and upwards, this organ shuts up the choannse, and 
at the same time opens the slit of the windpipe, situated just at its base, thus 
giving to the air a passage into the windpipe, and at the same time preventing 
its entrance through the choannae into the nose. In this way, the tongue takes the 
place, in a certain sense, of the velum palatinum of the higher Vertebrata, which 
is wanting in Turtles. After the air has passed into the windpipe, the tongue is 
drawn forwards, and thus the longitudinal glottis is again closed, while now the 
choannse are again opened to a free communication with the cavity of the mouth.3 
1 We find the same mode of breathing in the 
class of Batrachians; but for an entirely different 
reason, namely, on account of the absence of ribs. 
2 The existence of a diaphragm is erroneously 
denied to Turtles by Dumeril and Bibron, Erpe- 
tologie gene rale, I., p. 175. This work, however, 
worked out as it seems almost entirely by Bibron, 
is to this day the best illustration of the Zoology 
of Turtles, as it also is of the Saurians and Frogs, 
while the part relating to Ophidians, completed after 
the early death of that able herpetologist, Bibron, 
contains the most superficial descriptions of genera 
and species. 
8 In Amphibia, this process is similar, though not 
the same. It is easy to observe, that in this class 
the eye-bulbus is often active in swallowing the 
air; these large balls, when pressing downwards, 
narrow the cavity of the mouth, and the air moves 282 
AMERICAN TESTUDINATA. 
Part II. 
The trachea is generally rather short, divided near the base of the neck into 
two large bronchi, one of which is often so curved as to form a large arch. The 
lungs are very voluminous; more so in land than in water Turtles. This differ- 
ence alone, in the size of this organ, accounts almost entirely, both for the high 
arched body of the true land Turtles which never go into water, and for the 
flat trunk of the Trionychidae and sea Turtles, which hardly ever leave the water, 
except to lay their eggs. But even in the aquatic Turtles, the capacity of expan- 
sion of the lungs is great enough to allow them to remain for half an hour or 
more under the water, as I have had ample opportunities of observing in Trionyx, 
though it must not be forgotten, that in the family of Trionychidm, the skin being 
soft and thus more permeable to water, a kind of respiration of the blood may 
take place through the skin also,1 as is the case so extensively in Frogs. 
The following table shows the capacity of the lungs in those families, of which 
I was able to obtain fresh specimens at the time. The experiments were made 
upon the living animal by pumping out the air of the lungs, then pumping in 
water, then pumping out the water again and measuring its amount in cubic 
inches. This table shows that aquatic Turtles require much less air in their lungs, 
in proportion to the weight of the body, than land Turtles.2 It shows especially, 
that in mud and soft-shelled Turtles, the lungs being much reduced in size and 
importance, by far the greater part of the respiration must be performed by the 
skin of the whole body, which is much thinner in these families than in other 
Turtles; while, on the contrary, in the true land Turtles and that land Emydian, 
backwards. Again, we find in Frogs, at least in 
some, for instance in the genus Rana, a movable valve, 
by which it can close or open the nostrils at will; 
there is nothing of this kind to be found in Turtles. 
1 The beautifully ramified vessels, which are seen 
through the epidermis upon the entire lower sur- 
face of the body of Trionyx, add great weight to 
this supposition. See below, p. 284. 
2 It is moreover evident that the capacity of 
the lungs is not a family character, for while the 
Testudinina (land Turtles) are generally provided 
with much larger lungs than the Emydoidae, our 
table furnishes the unexpected evidence, that in a 
member of the latter family they are larger still. 
The capacity of the lungs in Cistudo, for instance, 
shows clearly its influence upon the form of the 
body, and it would thus seem that here, at least, 
form cannot characterize the family. But this very 
instance proves, on the contrary, the truth of the 
principle adopted for the limitation of families, as 
by a thorough examination we find still in the 
Cistudo the real character of the form of Emyds, 
in its sharp contradistinction from the Testudo 
family. See below, The Family Characters of Emyd- 
oidae. Hence it follows, that the mode of life, and, 
what depends upon it in the organization of the 
animal, the capacity of the lungs, the length and pro- 
portions of the intestine, etc., are generally, though 
by no means always, common to a family; and that 
such definite complications of forms as characterize 
families may be modified according to the different 
modes of life, without interfering with or changing 
the ideal combination. This ideal is the conception 
of the Divine Mind. The conception however is 
not changed, in the act of being expressed in living 
realities, but only specified; and this is done in the 
various members of a family, according to their 
mode of life, etc. Chap. I. 
283 
RESPIRATION. 
the Cistudo, the process of respiration is no doubt performed entirely by the lungs. 
This remarkable difference is not only owing to the greater or less thickness of 
the epidermis, but particularly to this circumstance, that air does not penetrate a 
horny epidermis so easily as water. Thus, aquatic animals probably absorb the 
water through the whole surface of their body, and that water, being impregnated 
with oxygen, is made subservient to respiration; while, on the contrary, animals 
living on land are much less capable of breathing through their skin, the air 
penetrating the epidermis with greater difficulty. This seems to be rendered 
evident by our table, if we compare Testudo with Trionyx. We suppose the 
same law may have its application in regard to the respiration of all animals; 
and that animals living in water generally require a much smaller development 
of the breathing organs proper than animals living in the atmospheric air. 
TABLE, 
SHOWING THE CAPACITY OF THE LUNGS COMPARED WITH THE WEIGHT OF THE BODY. 
Species. 
Mode of Life. 
Weight of the 
Body. 
Capacity of the 
Lungs. 
Length of the 
Carapace. 
Testudo polyphemus. 
( Gopher.) F emale. 
On dry ground and 
in sand-holes. 
95 Ounces. 
35 Cubic In. 
10| Inches. 
Cistudo triunguis. 
(Three Toed Box-Turtle.) 
Female. 
In dry woods, under 
leaves, etc. 
19 " 
17f " 
6% " 
Ptychemys rugosa. 
(Emys rubriventris.) 
(Red Terrapin.) Female. 
In water and on land. 
62 " 
22| " 
11 " 
Cinosternon pennsylva- 
nicum. 
(Mud-Turtle.) Female. 
In water and mud. 
8 " 
1 « 
2 
41 « 
'2 
Chelydra serpentina. 
(Snapping-Turtle.) Male. 
In water and mud. 
65 " 
7 " 
10 " 
Trionyx ferox. 
(Soft-shelled Turtle.) Female. 
In water and mud. 
76 " 
41 « 
^2 
13 " 
But there is another interesting circumstance, to which I would allude in this 
connection. Dr. A. Sager says, that, "arranged along the surface of the tongue 
of Trionyx and somewhat in rows, as well as on the fauces and about the rima 284 
AMERICAN TESTUDINATA. 
Part II. 
glottidis, and also over the edges of the cornua hyoidea, there exist a great num- 
ber of delicate fringes, resembling, especially on the hyoid arches, the fimbriated 
gills of the Menobranchus or the internal gills of a Tadpole."1 Before reading 
this paper, we had noticed these organs; but, after seeing this Turtle remaining 
under water for half an hour without showing the least sign of oppression, it 
seems plausible to assume that these fringes may be similar to the internal gills 
of Tadpoles, not only in their shape, but also in their function. There exists, 
moreover, an extensive network of beautiful vessels, spreading in elegant dendritic 
ramifications upon the whole lower surface of the Trionychidae, which can hardly 
have another function than that of assisting in the process of breathing, as they 
are too numerous and too large to be considered simply as the nutritive vessels 
of the skin. This is the more probable, as these vessels are very superficial, and 
only covered by a very thin epidermis. They are indeed as plainly visible, 
through the horny layer which protects them, as the vessels of any special external 
breathing organ, and give to the lower surface of the body, over which they 
extend, a very ornamental appearance. 
Turtles have a voice. Though I have myself made this observation only in 
a few species, namely, in Emys elegans, serrata, picta, and insculpta, which emit 
a piping note,2 and in Chelonia Mydas, whose voice resembles somewhat a quick, 
low bark. I am inclined to believe that all of them have, more or less, the 
faculty of emitting distinct sounds. Sphargis has its name even from crqpaeav/w, to 
make a noise. But, whether this name is meant only for that sharp hissing sound 
which all Turtles produce, when they are excited, or whether it is intended to 
designate a real voice, I am not able to state, as I have never heard the sounds 
emitted by Sphargis. However, it is reported of many Turtles, especially of the 
Chelonioidm, that they cry aloud when they are seriously wounded. 
I have not yet been able to ascertain to what extent the respiration is reduced 
or interrupted in those Turtles which burrow under the ground during the winter. 
In the more aquatic species, however, which secrete themselves in the mud, under 
the surface of the water, the pulmonary respiration is, of course, entirely suspended. 
The changes, which the other functions undergo in different families during this 
state of hibernation, have not yet been investigated. It would be easier to make 
these observations in the Southern States, where the waters remain open all the 
year round, than in the Northern States, where the ground is covered annually, 
for several months, by a thick sheet of snow and ice. 
1 Compare Dr. A. Sager's Notes on the Anatomy, 
etc., quoted above, p. 277. 
2 Dr. Weinland informs me that Emys europaea 
is known to produce a similar sound. Chap. I. 
285 
VASCULAR SYSTEM. 
SECTION XII. 
VASCULAR SYSTEM. 
The heart of the Turtles lies just above the liver. It is broad, nearly trian- 
gular, the wide basis of the triangle extending across the body. It is inclosed in a 
double sac of the pericardium, and attached to it, at its point, by means of a fold 
of the pericardium. The plan of its interior structure is the same in Turtles as 
in Ophidians and Saurians. While in Crocodiles there exists a true septum between 
both ventricles,1 as in Birds and Mammalia, we find in Turtles, typically, only one 
ventricle.2 
In a large specimen of Ptychemys rugosa, (E. rubriventris,) we had an opportu- 
nity of studying the beating of the heart. The process is as follows: The auricles 
are filled simultaneously, one with a bluish red, the other with a light red blood. 
When filled to the utmost, they have a triangular shape, with rounded corners. But 
while the auricles are already thus filling, the heart itself, the ventricle, is grad- 
ually expanding more and more; then a sudden contraction of the auricles throws 
all the blood into the broadly expanded, but empty, ventricle, which thus filled 
assumes the form of a high cone. Immediately after this follows the contraction of 
the ventricle, then follows a pause until the auricles are filled again, and the power- 
ful pump begins its play anew. This goes on about ten times in a minute. The 
rhythm in its details is as follows: First second, systole of the auricles; second 
second, systole of the ventricle; third and fourth seconds, the ventricle remains 
contracted; fifth and sixth seconds, the auricles are gradually filling; seventh 
1 This difference becomes, however, of less impor- 
tance when we remember the fact, that in Crocodiles 
there exists, at their very base, a communication be- 
tween the two trunks which start from the two ven- 
tricles of the heart, causing there a similar mixture 
of the dark and red blood, outside of the heart, as 
exists, in Turtles, inside of the heart. 
2 We cannot agree with the view generally adopt- 
ed, that this so-called imperfect septum in the heart 
of Turtles, which seems to divide it into two cavities, 
a so-called cavum arteriosum and a cavum venosum, 
is homologous to the perfect septum between the ven- 
tricles which exists in Mammalia and Birds. The 
fact, that the great bloodvessels (the aorta and the 
arteria puhnonalis) start together from the cavum 
venosum, seems to prove that the two cavities in 
the heart of Turtles, which are by no means very 
marked, do not correspond to the two ventricles in 
Mammalia and Birds, but, on the contrary, that, as 
stated above, the ventricle in Turtles is typically 
one, as in Fishes. Yet this one ventricle of Tur- 
tles is not any more identical with the one ventri- 
cle of Fishes than with the two ventricles of warm 
blooded Vertebrata, for in Fishes we find only one 
vessel, the aorta, arising from it, while in Turtles, both 
aorta and arteria pulmonalis start together from it 286 
AMERICAN TESTUDINATA. 
Part II. 
second, or first of the second contraction, systole of the auricles, etc. The whole 
rhythm was remarkably regular, except some variation in the measure of the last 
four seconds, which, as stated above, were generally thus divided into two pairs; 
but sometimes this division was not distinctly marked, the filling of the auricles 
beginning already in the fourth or even in the third second. As we have not 
found any important structural differences in the hearts of the most different 
families of Turtles, we are induced to believe that the rhythm observed in Emys 
rubriventris is probably the general rule for the contractions of the heart in all 
Turtles. This rhythm exhibits great uniformity, not only in the duration of the 
contractions as a whole, but also in the measure of its successive steps. 
Three large vessels, intimately connected at their basis, which is sometimes 
supported by a cartilaginous frame, arise from the ventricle. Two of them, car- 
rying red blood, soon form one common trunk, the aorta; but before this takes 
place, each of them sends off many vessels, namely, to the right the arteria 
anonyma, from which soon start the arteriae carotides and subclaviae, and to the 
left the arteries of the stomach and mesenterium. 
The venous system of Turtles agrees with that of other Reptiles. Two vena? 
anonyma) from before, and two from behind, the umbilical veins of Bojanus, open 
into the sinus venosus, which pumps the blood into the right auricle. It is char- 
acteristic of the Turtles, that the venae vertebrates - vena azygos of Bojanus, of 
which there are two, as in Saurians, while in Ophidians there is only one - run 
above the ribs in Turtles, while in all other Reptiles they run below the ribs. 
We find such veins in Turtles above the transverse processes of the vertebrae 
all along the dorsal column, and also in the neck and tail. There are more- 
over some veins, peculiar to Turtles, running from the liver directly to the heart, 
while in other Reptiles the vena cava receives all the veins of the liver. The 
blood of Turtles does not show different features from that of other Reptiles.1 
1 Its constituents, and its changes by starvation, 
thirst, etc., have been recently illustrated by Joseph 
Jones, q. a., p. 279. When taken from fresh speci- 
mens, the specific gravity of the blood of different 
Turtles varies from 1025 (Chelydra serpentina) to 
1034 (Emys reticulata.) The amount of solid constit- 
uents in 1000 parts varies from 105 (Chel. serpen- 
tina) to 156 (Emys serrata.) The water in 1000 
parts of blood varies from 895 (Chel. serpentina) to 
843 (Testudo polyphemus) ; the dried organic con- 
stituents (blood globules) vary from 56 in Chel. ser- 
pentina to 87 in Testudo polyphemus. Thus, as was 
to be expected, the blood of water Turtles is more 
watery than that of land Turtles. Jones (p. 23) no- 
tices another difference in the color of the serum, 
namely, that, while in some Turtles (Testudo poly- 
phemus) this color is light yellow, as in most Mamma- 
lia, Birds, Reptiles, Batrachians, and Fishes, it is 
golden in some Emydoidae, (Emys serrata, reticulata, 
concentrica,) as it also is in the black Turkey Buzzard 
(Cathartes atratus.) With reference to the influence 
of hunger on the blood, we find the following experi- 
ment related in the same paper. Emys concentrica, 
recently captured, had on the 16th of June a weight 
of 14,285 grains. Kept without food and drink for 
forty days, weighed, July 23d, 11,400 grains. Loss, Chap. I. 
UROGENITAL ORGANS. 
287 
The lymphatic system is very much developed in Turtles.1 Two hearts, lying 
near the base of the tail, immediately under the bony shield, and provided with 
fat cushions for protection against pressure, form the pump-work of this vascular 
system. Like the blood-heart, these lymphatic hearts are provided with transversely 
striated muscular fibres. Lymph vessels bathe all the arteries of the body, surround- 
ing not only the main stems, but running with them along all their branches. 
There lies a large lymph cistern between the lungs, opening into the ductus tho- 
racicus, which leads into the venae subclaviae. 
SECTION XIII. 
UROGENITAL ORGANS. 
'Urinary Organs. We find that the so-called primordial kidneys, or Wolffian 
bodies, which exist in all Turtles, as well as in all other true Reptiles, are built 
up, as in these, of fine canals, sending off a duct into the cloaca. We have 
never found a distinct secretion in this duct. Investigations about their relation 
to the real kidneys and to the genital organs have led us to results which are 
in many respects at variance with those of other authors.2 The urinary bladder of 
the Turtles is always more or less bilobed, and mostly onesided. It is remarkably 
large, and in land Turtles almost always filled. The ureters are short, the kid- 
neys lying in the cavity of the pelvis, outside of the peritoneum. The kidneys are 
generally flattened, and composed of many lobes. Their weight, in relation to the 
weight of the body, varies much in different Turtles, and the laws about this 
variation are not yet clear;3 but all of them have the kidneys two or three 
times smaller in proportion than other Reptiles. 
Genital Organs. While in Turtles the kidneys lie outside of the peritoneum, 
2885 grains. Amount of blood obtained, 400 grains; 
not more than one third the usual quantity. Solid 
constituents in 1000 parts, 199 ; water, 800. We quote 
this experiment only to show how intensively all the 
systems of the body are working on, even in this state 
of starvation, and how erroneous is the idea of a gen- 
eral torpor of such hungering animals. 
1 After this system had been first discovered in 
Turtles by Hewson, in 1769, and beautifully illus- 
trated by Bojanus in 1819, J. Muller discovered, in 
1839, the hearts which set it in motion. This impor- 
tant discovery of J. Muller seems, however, to be 
unknown to Rymer Jones, who, in the year 1852, in 
Todd's Cyclopedia, (Reptiles, p. 302,) denies the exist- 
ence of these lymphatic hearts in Turtles. They are 
easily found in any living Turtle, and may be seen 
beating for a long time after being laid bare. 
2 See Part III. of this work, where this point 
is fully considered. 
8 See p. 127 of Jones's paper, q. a., p. 277, note. 288 
AMERICAN TESTUDINATA. 
Part II. 
the spermaries and ovaries are situated inside of it. The spermaries are oval, 
and surrounded by a convolution of seminiferous canals, the lumen of which is 
large, whilst their walls are often provided with a large amount of black pigment? 
The spermatic ducts open into the cloaca on the top of a papilla near the open- 
ing of the urinary organs. The penis is single, large, and retracted into the 
cloaca, as in Crocodiles, while in Snakes and Lizards it is double, and lies outside 
of the cloaca.2 The form of the penis, particularly its end, exhibits great diversity 
in different families, the extremity being simple in Testudo and Emys, for instance, 
while it is branching in Trionyx. The ovaries are very much as in Birds. The 
number of eggs which are matured in one year is, as in Birds, very different 
in different families, genera, and species. The eggs of the ovaries are largely 
provided with bloodvessels. The oviducts begin with a tender but large tuba? 
often provided with beautifully folded margins. In relation to the reception of 
the eggs through these tubae, we have come, by numerous observations, to the 
strange result, that eggs from the left ovary are often received in the right tuba, 
and vice versa. This fact is clearly demonstrable. We have observed, in a 
large number of cases, that there were more corpora lutea to be found in the 
ovary of one side than eggs in the oviduct of the same side; and the eggs which 
were wanting in this oviduct were found in that of the other side, on which there 
accordingly appeared fewer corpora lutea than there were eggs in the oviduct. 
Whether this occurs only among Turtles, or, as we would rather believe, also in 
other Vertebrata, we do not yet know. During their passage through the oviduct, 
the eggs are provided with a thick, hard, calcareous shell, as in Crocodiles, while 
in all other Reptiles we find only a leathery shell. In connection with this, 
Lizards and Snakes have, while hatching, a sharp tooth, to cut through the shell, 
as with a knife.3 In Turtles, we find only a hard tubercle upon the snout, by 
1 We do not find ripe semen in the seminiferous 
ducts of the young Emys picta (of which we had a 
large series from the first year upwards) before it 
has attained the seventh year of its age. 
2 Stannius has established a primary division, 
among the Reptiles, upon this difference, and that 
other peculiarity of a free movable suspensorium 
for the lower jaw in Saurians and Ophidians, which, 
on the contrary, is immovable, and soldered by 
sutures to the skull, in Crocodiles and Turtles; 
Handbuch der Zootomie, Amphibien, Berlin, 1856, 
p. 5 and 7. lie there calls the Reptiles, Amphibia 
monopnoa; while the two large sections, founded upon 
the characters mentioned above, are his Strepto- 
stylica, embracing the Ophidians and Saurians, and 
his Monimostylica, the Crocodiles and the Turtles. 
Though we acknowledge a nearer relation between 
Snakes and Lizards, and a greater difference be- 
tween Saurians and Crocodiles, than is generally 
admitted, we cannot see, on the other hand, a real 
relationship between Turtles and Crocodiles. There 
is, at least, no more affinity between them than 
between Saurians and Turtles ; and, though a group 
comprehending Turtles and Crocodiles may be con- 
venient in an anatomical point of view, it seems 
to us at the same time artificial. 
8 This tooth was discovered by Johannes Muller, 
(see his Archiv fur Anatomie und Physiologic for Chap. I. 
UROGENITAL ORGANS. 
289 
means of which the young, like young Birds, break through the hard shell. Dr. 
Weinland tells me, that in a beautiful series of specimens of Crocodiles in the 
Museum of Berlin, the snout of the embryo about hatching is sufficiently hard 
to break the egg, and that there is no such tubercle upon it; neither is there 
a tooth in the intermaxillary bone for this purpose. 
The cloaca is very large in both sexes; it opens on both sides into a large 
pouch, (sacci anales,) the function of which is not yet fully ascertained; it may 
stand in connection with the reception of water into the cloaca, mentioned above. 
The cloaca is exceedingly long in Trionyx. In female Turtles, we see in the 
bottom of the cloaca a longitudinal furrow, with thick, rounded walls, running out 
generally into fringed appendages behind. This serves as a vagina in the act 
of copulation. Interiorly we find, in the cloaca, first, the opening for the urine, 
then behind and outside of it, on each side, that for the oviduct. 
The copulation is generally said to take place only once in a year; but my 
observations have satisfied me, that, at least in some species, it takes place twice 
every year, namely, in the spring and in the autumn. 
It is, perhaps, the proper place to mention here some glands in Turtles which 
open outward and secrete a strong, odoriferous oil. These glands seem to have 
a more immediate reference to the relations of the animal to its fellow-beings 
than to its own individual organism. We find such glands in the lower jaw in 
Testudo, in the neck and shoulder region in sea Turtles, while in the family of the 
Cinosternoidm there are two larger glands on each side under the carapace, near 
the bridge which unites the carapace and plastron, the excretory ducts of which 
the year 1841, p. 329 and foil.) The operation of the 
tooth itself in the living animal has been observed 
in young Snakes, while hatching, by Dr. Wein- 
land, (see Wurttembergische naturwissenschaftiche 
Jahreshefte, XII., for the year 1856, p. 90 and foil.,) 
so that there can be no doubt about the function of 
this strange tooth, which is fixed in the intermaxil- 
lary bone, where afterwards, at least in most Snakes, 
no tooth at all is to be found. Nor can there 
be any question of its being common to all Snakes 
and Lizards, when hatching, for after Muller had 
already found it in very different families, it has 
been traced by Dr. Weinland in all the German 
Snakes and Lizards. Now neither J. Muller nor 
Dr. Weinland could find this tooth in the young 
Crocodiles when hatching. This is remarkable, 
because it strangely coincides with the suggestion of 
Stannius, (see above, p. 288, note,) to unite the 
Snakes and Lizards on one side, and the Turtles 
and Crocodiles on the other side, into two large 
groups; the first of which have such an egg-tooth, 
whilst the latter have none. But, as far as the 
Turtles and Crocodiles are concerned, this resem- 
blance is evidently only negative, and cannot, there- 
fore, prove any affinity; while the fact, that the 
egg-tooth is common to the Lizards and Snakes, is 
another striking instance of their close affinity, and 
of the correctness of the views of Stannius, who 
proposes to unite them into one group, in opposition 
to Turtles and Crocodiles, as Merrem has already 
done. Thus, the Reptiles would really form only 
three large groups, one comprehending the Lizards 
and Snakes, another the Crocodiles, and a third 
the Turtles. 290 
AMERICAN TESTUDINATA. 
Part II. 
run through the bone and open outward by a fine slit in that bridge. The 
Crocodiles have one large musk gland on each side near the inner and lower 
edge of the two branches of the lower jaw, not far from their posterior angle. 
The position of these glands is nearly the same as in Testudo. Many Saurians 
have similar glands on the lower surface of the thigh. In Chelydra there are 
no such glands, though they emit a musk-like stench, quite as strong as that of 
the Cinosternoidse. It is however possible, that in this family the odor arises 
from a large number of small glands opening between the warts of the skin; 
but I neglected to examine this point in the proper season. Though the pro- 
duct of these glands may be of some use in keeping the skin fat and elastic, 
still its more important function may be to enable the sexes to find each other 
at the time of copulation, as we observe it so plainly in Snakes. 
SECTION XIV. 
THE DEVELOPMENT OF TURTLES FROM A ZOOLOGICAL POINT OF VIEW. 
The growth of Turtles is exceedingly slow. In this respect they differ greatly 
from the Batrachians, which complete their growth, either entirely or nearly so, 
during the first year of their life. The true Reptiles, on the contrary, acquire 
slowly the age of maturity; and among them the Turtles are the slowest in their 
growth, and acquire latest, as far as we know, the period of puberty. I have 
collected data which prove satisfactorily that our common Emys (Chrysemys) picta 
does not lay eggs before it is ten or eleven years old; and even then it is by 
no means full grown. 
Like most other Reptiles, Turtles lay their eggs either in moist ground, or in 
dryer places near the water, (fresh-water Turtles,) or in dry ground, (land Turtles,) 
or in hot sand, (Chelonioidse.)1 The embryo breaks through the shell of the egg 
by means of the horn it has upon its snout, (see above, p. 288,) after an incuba- 
tion varying, in different genera or families, from six weeks to three or four 
months and even more.2 The outline of the carapace of all Amydae, at the time 
of its formation, is remarkably similar, namely, ovate, or orbicular and flat; at least, 
this is the case with all the young which I have had an opportunity to see. 
There may be an exception with reference to these features in Testudo only, 
1 Respecting the laying of the eggs, more will 
be found in Part III. 
2 For more details respecting the act of incuba- 
tion, see Part III. Chap. I. 
GROWTH OF TURTLES. 
291 
which I have not seen in its youngest state. In the Trionychidse, this flat, orbic- 
ular form is preserved through life, and in the Emydoidm during the first four 
or five years, at least; but by and by the shield assumes the more or less ellip- 
tical and higher form of the adult, according to the different genera and species. 
This change takes place earlier in the Chelydroidm and Cinosternoida) than in the 
Emydoidae, and earlier still in the Chelonioidm.1 In this last family, the character- 
istic features of the adult are already sketched out in the first year, though not 
yet fully developed. In the family of Chelydroidae, the embryonic characters are 
prevalent for two years at least; in that of Cinosternoidm the characters of the 
young do not disappear before the fourth year. It is nevertheless true that each 
family has its special pattern. 
The young Turtles are mostly so different from the adult, in all their features, 
that it is very difficult to identify them. At all events, it requires a long experi- 
ence to recognize them, in these first years, for what they are. Our systematic 
works, even the most recent, furnish, in fact, the painful evidence that these young 
Turtles have repeatedly been mistaken for distinct species. On the other hand, 
it is worth mentioning, that Turtles belonging to the same genus, as the genera 
are circumscribed below, show already in the youngest state slight peculiarities 
which at least indicate the genus, though the generic characters are by no 
means all developed. In the family of the Emydoidm, I have further observed 
that the young approximate the lower Testudinata, not only by their remarkable 
similarity with the Chelonioidm in the earlier stages of their embryonic develop- 
ment, but also by their mode of life, which is much more aquatic than that of 
the adult of the same species. This agrees remarkably well with the law, which 
seems to exist throughout the animal kingdom, that aquatic animals rank lower 
than the terrestrial representatives of the same groups.2 It may be remembered 
in this connection, that in a large number of Insects the larva) live in the water, 
while the perfect Insects are entirely aerial. Still greater differences, in the mode 
of life and the form of the young and adults, may be observed among parasitic 
Worms. Among Vertebrates, similar differences are particularly obvious in the 
class of Batrachians, in which the young of some of their representatives are 
entirely aquatic, whilst the adults live exclusively upon land. At least, this is 
the case for the highest among them, the Toads. These remarks in relation to 
the development of the form, and the mode of life, which is more or less con- 
nected with the form, may be sufficient to show how important the study of 
young animals is with reference to a correct appreciation of their true relations. 
The following table gives a complete view of the changes which our common 
Chrysemys undergoes in its form. 
1 See Part III. for further details. 
2 Compare Part I., Sect. 9, p. 30. 292 
AMERICAN TESTUDINATA. 
Part II. 
TABLE, 
SHOWING THE SUCCESSIVE CHANGES IN THE RELATIVE DIMENSIONS OF THE BODY IN EMYDOIDAS. 
Species. 
Age. 
Sex. 
Height of 
the Box. 
Dorsal Shield. 
Ventral Shield. 
Length of 
the Tail. 
Length. 
Breadth in 
the Middle. 
Length. 
Breadth in 
the Middle. 
E m y s p i c t a, 
Second year.1 
12 Mil. 
261 
25 
25 
18 
161 
Auct. Now 
Third year. 
Male. 
17 
42 
391 
37 
24 
n* 
C h r y s e m y s 
Fourth year. 
F emale. 
2H 
51 
49 
44 
371 
201 
p i c t a, Gray. 
Fifth year. 
F emale. 
231 
54 
51 
50 
39 
21J 
Sixth year. 
Female. 
25 
59 
56 
54 
421 
231 
Seventh year.2 
Male. 
261 
66 
60 
60 
47 
26 
Seventh year. 
Male. 
27 
67 
60 
60 
471 
261 
Eighth year. 
Male. 
28 
72| 
61 
68 
50 
27* 
Ninth year. 
Male. 
28 
74 
62 
70 
50 
271 
Tenth year. 
Male. 
30 
77 
64 
73 
531 
28 
Eleventh year. 
Male. 
30 
80 
67 
76 
54 
281 
Fourteenth year. 
Male. 
33 
92 
741 
85 
60 
281 
Twenty-fifth year. 
F emale. 
43 
121 
92 
113 
80 
34 
Old. 
F emale. 
47 
129 
96 
1201 
81 
37 
Very old. 
F emale. 
59 
163 
113 
154 
95 
53 
C h r y s e m y s 
Sixth year. 
Male. 
29 
68 
59 
63 
47 
27 
(Emys) 
Old. 
Male. 
35 
99 
77 
92 
63 
40 
B e 11 i i, Gray. 
Very old. 
Female. 
59 
155 
110 
145 
93 
50 
There is another feature which, though of less importance, still allows a gen- 
eralization worth mentioning, I mean the change of color in Turtles of different 
1 As Turtles lay their eggs in the spring, the 
specimens selected for examination were all collected 
in the spring; the starting point of comparison is, 
therefore, really the second year of their develop- 
ment. However, as the eclosion takes place only 
late in the summer, the young had only been hatched 
six months when picked up, though they are con- 
sidered here as one year old, on account of the 
long period of incubation. Moreover, there is very 
little difference between specimens recently hatched 
and those collected the following spring. 
2 After the seventh year, it is much more difficult 
to distinguish the age of those Turtles, which, like 
Chrysemys picta, have a perfectly smooth epidermis, 
than during the earlier years. I have, however, 
been able to determine it with tolerable precision, 
by collecting large numbers of specimens at the 
same time and in the same season, and assorting 
them according to their size, and comparing the 
sets thus formed with specimens of other species, 
in which the successive lines of growth indicate the 
number of their years. During the first six or seven 
years the rate of growth is so uniform that numer- 
ous specimens collected at the same time are readily 
arranged in sets of the same age, simply by the 
difference they show in their size. Chap. I. 
GROWTH OF TURTLES. 
293 
ages, and the simplicity of their forms. As a roundish form is an attribute 
of the young, which we may trace throughout the animal kingdom, so also 
has simplicity of ornamentation, particularly of color, been considered as charac- 
teristic of the younger age. Most Birds furnish examples of this law, in their 
monotonous gray plumage at the time of hatching, when contrasted with the 
beauty, gayety, and variety of colors in the adult. But in Reptiles this law is not 
so obvious, and there are even very striking exceptions, if the opposite is not 
actually to be considered as the rule. A Boa constrictor, a striped Snake, a 
Rattlesnake, when hatching, show the same purity of colors as the adult, or even 
a greater brilliancy. The same seems to be the case with Turtles, if we compare, 
for instance, the beautiful network of yellow lines in Graptemys Lesueurii and 
geographica, when hatching, with the pale colors of the adult. Still, the law 
mentioned above is maintained, at least thus far, that few young Turtles have 
really purer colors than the adults. Yet there are some, which in middle life 
are more brilliant than either in their earlier years or in old age. This is, for 
instance, the case with Ptychemys concinna, (E. floridana,) and rugosa, (E. rubri- 
ventris,) and with Emys Meleagris, (Cistudo Blandingii.) From all those instances 
which I have investigated more thoroughly, it may be inferred that the fading 
of the colors in adult specimens is either owing to the thickness of the grayish 
epidermis, which thus obscures the Malpighian layer, in which the color resides, 
or to external mechanical influences which injure the smoothness of the epidermis. 
In order to illustrate this subject more fully, I add in a note more minute 
details relating to the development of Chrysemys picta, not only as far as its 
form is concerned, but also respecting its colors. A large series of specimens of 
all ages, from the youngest, just hatched, to the adult, including very old ones, 
collected in the same season of the year and at the same time, enables me to 
present this sketch.1 I have selected this species to illustrate the changes which 
1 When comparing young specimens of our most 
common Turtles with adult ones, our Emys picta for 
instance, when just hatched, there are three points 
which strike us at first sight. A large, full head, 
a circular, flat carapace, and a long tail, vertically 
compressed. The head, at first almost a regular ball 
with three prominences, the two large eyes and the 
nose, becomes in more advanced age more and more 
pyramidal; it has in the adult four distinct sides, a 
very flat upper surface, two lateral surfaces, which 
are slightly bent, and a flat under surface. But it 
is remarkable, that in Emys concentrica, and also, 
though in a less degree, in the type of Emys floridana, 
that youthful form of the head continues throughout 
life. This is more remarkable still, if we remember 
that just these species are the most aquatic among 
Emydoidce, and further that our young Emys picta 
is itself much more aquatic in its habits, during the 
first years of its life, than it is in later life. In 
relation to the changes of the forms of the carapace, 
I have presented these in the shape of a table, in 
which the differences arising during the growth, in 
the relative proportions of the different diameters 
of the body, may be seen at a glance. See p. 292. 
Thus we may say that this Emys, for the first 
four or six years of its life, has the shape of the 294 
AMERICAN TESTUDINATA. 
Part II. 
Testudinata undergo with age, not only because I have been able to obtain a 
much larger number of specimens, but chiefly because I have had ample oppor- 
carapace of a Trionyx, and that like this, it lives 
almost exclusively in water. This is also the 
reason why, in spite of the much larger number of 
young than of adults, (which exist no doubt among 
these animals, as in most species throughout the 
animal kingdom,) the young Emydoidae are still so 
rare in our museums, and almost unknown to zoolo- 
gists. Nothing could prove more directly this differ- 
ence in the mode of life of the young and the adult 
than the fact, that though Emys insculpta is so com- 
mon in the neighborhood of Lancaster, about forty 
miles from Boston, that I have at times collected 
over one hundred in an afternoon, aided by a few 
friends, I have never yet been able to obtain a 
single young specimen of the first year, even though 
a whole school of young men were called to aid in 
the search. Professor Baird has found the same 
difficulty in obtaining young Emys rugosa for me, 
and though he offered a high price for them, he 
could not obtain more than a single specimen of 
the first year. And yet this species is so common, 
that, in the season, hundreds are daily brought to 
the market of Washington. 
By and by the bulk of the body becomes more 
concentrated in the middle ; the lungs of land species, 
being larger in proportion than those of aquatic 
ones, (see above, p. 283,) require a larger develop- 
ment of the carapace in height; and Emys picta 
of the seventh year, which is now ready to go from 
time to time on land, assumes at this age the shape 
of the Nectemyds. Then it approaches more and 
more the rounded form of the land Turtles; this 
is, however, never reached in this species, though it 
is actually the case in a higher genus of Emydoidae, 
the terrestrial Cistudo. 
The retrograde development of the tail, as shown 
in our table, furnishes another proof of the truth 
of these comparisons. At first, in the hatching 
Turtle, the tail is vertical, compressed laterally, and 
very long in proportion to the size of the animal, 
indeed, nearly as long and powerful as in Chelydra, 
and, like the tail of a Tadpole, serves as a kind of 
rudder, strong enough to direct the course of that 
living flat-boat with its four paddles. Thus, as 
in the flying Bird, the tail is to be looked upon as 
a locomotive organ. But afterwards it does not 
grow in the same proportion as the body; and 
while in the young it was one of its most im- 
portant parts, it is, on the contrary, in the adult, 
a mere appendage to the body, weak and useless 
for the locomotion of that heavy bulk. I may 
add here, that the tail is also rather long in Triony- 
chidae; and that in the family of Chelydroidae it 
is most powerful, and clearly subservient to loco- 
motion, in darting the body forwards or in turning 
it over when on its back ; while in Cistudo it nearly 
disappears, or at least loses all significance. 
Again, the legs, in their development in the young 
as compared with the adults, show similar meta- 
morphoses, though not in the same degree in our 
species as in some others, E. guttata or insculpta, 
for instance. Being really broad paddles in the 
young, they become stiffer and more compact in 
the adult, to suit their habit of walking on the land, 
as well as swimming in the water. In Cistudo, 
the highest Emydian, they have reached the form 
of feet adapted to walking, instead of broad paddles, 
and so we find the slender fingers soldered together. 
In one species of this genus, one of these fingers 
has even faded away to a single phalanx, which 
does not reach beyond the skin, or only shows, when 
young, a very small nail projecting sideways. 
We now proceed to a comparison of the horny 
plates of the young E. picta with those of the adult. 
I would also refer to the Plates I., II., III., and IV., 
which exhibit accurate drawings of the young of a 
number of other species of our Turtles. PL XXVI. 
represents, besides, several young Ptychemys rugosa, 
(Emys rubriventris,) and Pl. XXVII. adults of 
the same species in different varieties of color. 
A glance at the horny plates of both shows a great 
difference in form. The following changes take place 
in the development of these plates in Chrysemys 
(Emys) picta. The plates of the dorsal side of this 295 
Chap. I. 
GROWTH OF TURTLES. 
tunities of watching it for ten successive years. The other species, of which I 
possess less extensive series, are described in the following, third, Chapter. 
Turtle, when hatching, are angular, when adult, 
rounded; the median ones are twice as broad as 
high in the young; they are as broad as high, or 
even higher than broad, in the adult. Granulated 
in the young, they are smooth in the adult. The 
granulated plate of the first year continues in some 
land Turtles, and also in Cistudo virginea, some- 
times throughout life, as the centre of the plate. 
In Chrysemys, and in most Emydoidie, the plates 
become entirely smooth after the second year. 
We meet similar discrepancies in reference to the 
plates of the plastron. While in the young they 
have all the same longitudinal diameter, they are 
of very different length in the adult, the three pos- 
terior pairs, particularly the second pair of the con- 
necting plates, becoming much higher. All these 
changes in the form of the plates are, of course, 
connected with the changes of the general form of 
the carapace, as described above. We find, for the 
first time, the form of adult plates in specimens 
about six years old. But I must mention here 
a remarkable exception, which I once met with 
in this species, namely, a fine specimen of more 
than seven years exhibiting still all the forms of 
the plates of the young when hatching. 
We observe similar changes with reference to 
colors. In Chrysemys picta just hatched, the back 
is of a dark gray brown color with a yellow middle 
line. The marginal plates are red above, each 
with three semicircular bands, the lowest one the 
broadest; they are red below, with a black circle. 
The plastron is red, in some specimens with a black, 
bottle-like mark in the middle, occupying the innei* 
margin of all the plates of the plastron. The head 
is brown, with yellow stripes; a yellow spot behind 
each eye, and a broad, club-like band on each side 
running behind, are particularly conspicuous; over 
these there are yellow spots along the neck. Similar 
bands, forked in front, extend from the angle of the 
mouth to the fore leg; two other yellow bands are 
seen along the under-side of the neck; and finally, a 
short, imperfect one runs backwards from the middle 
of the lower jaw, not touching the former ones, as 
in the adult. The fore legs have one red middle 
stripe in front, and another, very short, above it. 
All phalanges have reddish lines. The hind part 
of the fore leg is dark brown, with some little white 
spots. The hind legs are dark in front, with two 
yellowish bands behind, the lower one originating 
from the base of the tail, where it meets that from 
the other side, and hence forms one stripe along the 
under-side of the tail. The tail is marked above in the 
same way by a yellowish line, forked near the root. 
In the dress of the Turtle during the second year, 
there appear entirely new yellow stripes across the 
back, coloring the anterior margin of the plates and 
joining the yellow median stripe, which grows then 
much broader. Moreover, the plastron is no longer 
red, but yellow. The black mark upon it, if it still 
exists, extends only from the fourth pair of plates 
to the last. All the stripes upon the legs and feet 
are no longer red, but yellow. In the third year, 
the colors are brighter, especially the yellow cross 
bands on the back, which now turn reddish, extend- 
ing more and more over the margins of the plates, 
with the exception of the exterior margin. The 
marginal plates, light red until now, change into a 
splendid purple. In the fourth year, we see already 
all the colors of the adult, though the Turtle of this 
year is not yet half-grown, and though its general 
roundish form, as well as the form of the head, of 
the tail, and of the single plates, still exhibits rather 
the youthful than the adult characteristics. (Comp, 
the table above, p. 292.) 
It is interesting to follow out the same develop- 
ment in another Emydian, Chrysemys Bellii, which 
is very nearly related to Chrysemys picta. The 
organic laws of its development are exhibited 
in the same way as in Chrysemys picta, but 
we learn here that the specific character, so far 
as the coloring is concerned, namely, that black, 
bottle-like mark, (which we find so largely devel- 
oped in the adult Chr. Bellii, while it is entirely 
wanting in the adult Chr. picta,) is already very 296 
AMERICAN TESTUDINATA. 
Part II. 
SECTION XV. 
THE PSYCHOLOGICAL DEVELOPMENT OF TURTLES COMPARED WITH THAT OF THE OTHER 
ORDERS OF REPTILES. 
It is a question of the greatest interest, and one which must arise in the mind 
of every reader who has entered into the spirit of the First Part of this work, 
whether the psychological development of animals rises in the same degree as the 
development of the complication of their structure generally. If this be the case, 
it follows directly that the rank of the orders expresses at the same time the 
range of their psychological development. And we think that this is really the 
case. Now since we have shown that, owing to the complication of their structure, 
the Turtles are really the highest order among Reptiles, wTe must expect to find 
in them also the highest psychological development of the whole class, higher 
indeed than that of Lizards and Snakes. 
But, to measure the psychological development of animals is one of the most 
difficult tasks in natural science, since it can only be done by a comparison of 
those functions through which the mental energies are manifested, and the grada- 
tion and intensity of which are not so easily ascertained as those of other organs. 
These functions are, the sensations and the motions. 
With reference to the sensations, it cannot be doubted that they stand in 
distinct in the young animal when hatching, more 
so indeed than in Chr. picta, in which, as stated 
above, I have sometimes seen such a mark when 
young; and while it now increases in Chr. Bellii, 
it disappears entirely, in the two or three following 
years, in Chr. picta. Then again, in relation to 
the form, we find that the specific character of the 
carapace, by which Chr. picta and Chr. Bellii are 
so easily distinguished when adult, (the large diame- 
ter of the hind part of the shield in comparison to 
its front part, as we meet it in Chr. Bellii, while 
in Chr. picta both these diameters are nearly 
equal,) only appears about the seventh year. Thus, 
we see that in this development there is not a 
definite and regular series in the appearance of 
specific, generic, family, and ordinal characters; a 
specific character may appear, while the family 
character is not yet marked. The young Chrysemys 
Bellii, when hatching, has really in its forms, which 
constitute family characters, not much more relation 
to the family of Emydoidae than a Trionyx, when 
hatching, while it already exhibits its specific coloring 
in contradistinction to that nearly allied species, 
Chr. picta. The idea that an animal, in its develop- 
ment from the egg, exhibits first, class, then order, 
then family, then generic, then specific characters, 
may be true in some cases, but it is certain that in 
most species this is not the case. On the contrary, 
I do not hesitate to say that there are many ani- 
mals which exhibit in their youth the characters 
of a different family from that to which they really 
belong when adult. It is evident that if this be 
the case, the supposed law, above alluded to, is 
positively denied in nature. Chap. I. 
PSYCHOLOGICAL DEVELOPMENT. 
297 
direct relation to the development of the organs of the senses and of the brain; 
while the motions are dependent upon the development of the muscular system. 
Now, accurately to determine the standing of the Turtles in their class, as 
far as their psychological development is concerned, a glance at the position of 
the whole class, in its branch, may furnish some valuable hints. Though the 
orders have been represented1 as the natural groups which, being founded upon 
the complication of the structure of animals, above all determine their relative 
rank, it is equally true, that the classes, when compared with one another, stand 
lower or higher, in proportion as the systems of organs which are developed in 
them have a higher importance, or are built upon a more perfected pattern. In 
the branch of Vertebrata, there can be no doubt that the class of Fishes, as a 
whole, occupy the lowest position, that Amphibians rank next to them, that 
Reptiles come next, that Birds stand above these, and that Mammalia are the 
highest. Their whole structure shows this plainly. But, to consider only the 
points which have a bearing upon the question under consideration, it is obvious, 
that the Fishes, in which the whole bulk of the body is one undivided mass, 
the vertebral column continuous in one horizontal line with the base of the skull, 
the muscular system uniformly extended over the whole trunk, so as to allow only 
lateral motions, and the limbs reduced to branching digitations without concen- 
trated activity; in which the brain is only a slight enlargement of the spinal 
marrow, and some of the organs of senses are either wanting or very imperfect, 
while the others are rather blunt and obtuse; - it is obvious, I say, that this 
class occupies, not only structurally, but also with reference to its psychological 
endowment, a much lower position than the classes of Amphibians and of true 
Reptiles, in which the different regions of the body are more distinct, the motions 
more localized, the organs of the senses more perfect, and the brain larger. 
In these two classes, the preponderance of the head is already fully indicated 
by its position, being somewhat raised above the bulk of the body and forming 
with it a more or less marked angle, whilst in most of them the limbs are 
detached as locomotive appendages, distinct from the trunk, though not yet so 
free as to move with perfect independence. In Birds and Mammalia, the progress 
is still more distinct. The different regions of the body are not only better 
marked, they are also more diversified in their structure; the body is no longer 
so prone upon the medium in which the animal lives; the head has acquired a 
special movability in connection with the highly organized organs of the senses, the 
larger brain and the commanding position it has assumed; the motions also are 
more diversified, not only in themselves, but the anterior and posterior pair of 
1 See Part I., Chap. 2, Sect. 3, p. 150, 
38 298 
AMERICAN TESTUDINATA. 
Part II. 
limbs are even sometimes adapted to different purposes. All these features are 
brought to a climax in Man, whose vertical station presents the highest contrast 
with the horizontal position of the body in Fishes; whose head is so raised as to 
stand free above the whole frame, while the hands have become the willing tools 
of the manifestations of his mental powers. The gradation, as far as the structure 
is concerned, is as evident as possible, from the unwieldy, massive, horizontal body 
of the Fish, up to the commanding attitude of Man; and that this structural 
gradation stands in immediate correlation to the degree of the psychological 
development is equally evident, when we compare the mental powers of Man 
with the imperfect faculties of the Fishes. 
With reference to the motions in particular, Dr. Weinland has presented very 
interesting considerations, in a paper read not long ago before the Boston Society 
of Natural History.1 He remarked, that there exist in animals two kinds of 
motions, entirely different from one another, which, however, have not as yet been 
duly distinguished. If we watch attentively the motions of a dog, for instance, 
we soon perceive that they are partly subservient to himself only; such are his 
motions when eating, drinking, etc.; while he performs many other motions with 
his eyes, his ears, his tail, his whole body, by which he evidently intends to show 
to other animals or to Man, the state of his mind, what he thinks, feels, or wants. 
Dr. Weinland calls the first kind of these motions "subjective;" the second, 
" sympathetic." He showed that the first are common to all animals, while the 
second appear only in the higher types,2 and culminate in Man. Moreover, the 
higher perfection of the organs for sympathetic motions, as observed in Man, 
expresses at the same time his higher psychological standing. The gradation 
observed in this respect, in the different classes of Vertebrata, is not less appre- 
ciable. The Fishes, lying horizontally in the water, move simultaneously the whole 
body by the lateral bendings of the vertebral column, and the fins perform only 
locomotive functions; the eyes are little movable, and without expression. Fishes 
have no voice, indeed hardly any means by which they can communicate with 
their fellow-creatures, and yet they may be seen moving together in such a man- 
ner as to indicate a kind of concert; I have even observed some playing with 
one another. 
In Batrachians and Reptiles, the sympathetic motions are already more varied, 
the relations of the individuals of the same species to one another are more exten- 
sive and more frequent, and their ability to emit sounds almost universal, though 
these sounds are still very monotonous. With the Birds and Mammalia, all these 
1 See Dr. Weinland, " On the Motions of Ani- 
mals," in Proc. Boston Society of Nat. History, 1856. 
2 It is impossible, for the present, to extend 
such investigations to the faculties of Invertebrata. Chap. I. 
PSYCHOLOGICAL DEVELOPMENT. 
299 
relations become more intimate, and acquire a character of intensity unknown among 
the cold-blooded Vertebrata. In Man, the vertical station renders the whole body 
better adapted to perform sympathetic motions, and the organs themselves, by 
which they are performed, are more perfect; the hand especially, still a locomotive 
organ in the Monkeys, is, next to speech, the most expressive organ of Man. With 
it he strengthens his word; with it he grasps the hand of his fellow-man; with it 
he presses his mate upon his heart. Need I add, how expressive are the lips, the 
eyes, the tongue, the organs of the voice, and even the attitudes of the body, in 
giving utterance, by their diversified play, to our thoughts, our feelings, and our 
emotions-joy, love, grief, or hope! 
In this series, the true Reptiles occupy an intermediate position between the 
Batrachians and Birds. But if we apply the same test to the Turtles in particular, 
we cannot fail to see that, as the complication of their structure assigns to them the 
highest position in their class, so also is their psychological development highest 
among Reptiles. No one can fail, on the contrary, to see that the place assigned to 
the Snakes, at the bottom of their class, while the Lizards stand in an intermediate 
position between them and the Turtles, is as well justified in a psychological point 
of view as it is by the complication of their structure. Their whole body is used 
for locomotion; there are no limbs; the head and neck are buried in the uni- 
form cylindrical body; the eyes are nearly immovable; there is no voice but a 
kind of hissing, which may express at times fear, at other times fierceness. This, 
and certain bendings of the whole body, or an uplifting of its front part or of 
the tail, and a feverish shaking of the latter, as we see it particularly in some 
poisonous Snakes when near their prey, are the only motions by which Snakes 
show to other animals or to Man, the state of their mind. Fear and ferocity 
are indeed the only psychical emotions which have been observed in Snakes by 
the most attentive observers. If we compare a Snake near its prey with a Liz- 
ard in the same employment, we may admire the shrewd prudence of the latter, 
while we are astonished at the awkwardness of the former. The Lizard, turning 
its head now on one side then on the other, watches carefully the fly it has 
espied, and at once catches it by a quick motion, which he makes, however, only 
when sure of success. On the contrary, we may often see Snakes striking again 
and again in the direction of their prey before they catch it. There are more- 
over no eyelids in Snakes, while they are much developed in Lizards, and capable 
of the liveliest motions. The eyelids render the eyes of the Lizard expressive, 
and from these alone we may ascertain whether they are lively or depressed, 
while the eyes of the Snake are unexpressive, cold, and unchanging. Snakes see 
only; Lizards look. And now what is the further step of psychological devel- 
opment made from the Lizards to the Turtles ? The neck, in the first place, 300 
AMERICAN TESTUDINATA. 
Part II. 
has become still freer than in Lizards; and secondly, the head moves indepen- 
dently of the neck, which was not yet the case in Lizards. With this structural 
condition, the foundation is laid for a higher and more conscious relation to the 
surrounding mediums than is observed in Lizards. The ability to move the head 
freely upon the neck furnishes a larger horizon for the senses, which are situated 
in the head, and by this a more extensive and more accurate perception of the 
surrounding world may be obtained than we can suppose in those animals in which 
the neck is buried in the body, as in Fishes and Snakes, or in which the head 
at least is buried in the neck, as in Lizards. But even the legs, which, as in 
Lizards, seem to be subservient only to locomotion, perform in addition, in Tur- 
tles, functions which we would hardly suppose in these animals. Professor Jeffries 
Wyman had once the rare opportunity of watching two Chrysemys picta while 
making love, and he saw the male caressing and patting the head of the female 
with its fore feet for several minutes. Thus among Reptiles the fore feet have 
become, in Turtles, organs for sympathetic motions; but we are not aware how far 
this is extended to the whole order. Moreover, the voice of Turtles is superior 
to that of Lizards, which are only able to emit that hissing sound which is com- 
mon to all Reptiles. 
In conformity with this higher psychical endowment of the Turtles, their brain 
is much more developed than in the other Reptiles, particularly the large hemi- 
spheres.1 Still it is true, that Turtles are in some respects more insensible than 
other Reptiles, or at least than Lizards. They resist hunger and thirst, and the 
effect of wounds, easier than Lizards. This shows, no doubt, a slower process 
of change in the materials of which the body is built up, and accordingly also 
a lower vital energy generally. But, on the other hand, we must not forget that 
our observations of the habits of Turtles have for the most part been made upon 
individuals kept in captivity. If we walk along our ponds, and watch our Emy- 
doidae, sunning themselves on the shore, or on logs floating upon the water, they are 
by no means so slow and lazy as they are so generally supposed to be. They may, 
on the contrary, be seen attentively looking around and stretching out their neck 
to the utmost, as if listening. At the slightest noise of our steps, and with a 
quick motion of their paddles, they disappear under the surface of the water. 
If, now, in captivity, the same animal becomes more or less awkward and slow, 
we ought to remember, that the higher an animal stands, the more it feels 
the privation of its liberty; and my long experience with Turtles has satisfied 
me that they do feel the change, when confined in narrow enclosures. 
1 See above, Sect. 8, p. 274. 301 
Chap. I. 
GEOGRAPHICAL DISTRIBUTION. 
SECTION XVI. 
GEOGRAPHICAL DISTRIBUTION OF THE TESTUDINATA. 
The distribution of the Testudinata upon the surface of our globe presents 
some very interesting features, which deserve the more to arrest our attention, as 
they bear directly upon the very principles which regulate the geographical dis- 
tribution of the animals in general. In the first place, we find that, taken as 
a whole, the range of the Testudinata is less extensive than that of the other 
orders of Reptiles. This agrees with the general fact, that the higher representa- 
tives of any comprehensive group are everywhere more limited in their distribution 
than the lower types of the same group; and as we have seen that the Testu- 
dinata are the highest Reptiles, we should expect to find them, as is really the 
case, occupying a more limited area of the surface of the globe than either the 
Saurians or the Ophidians. This is equally true of their horizontal and of their 
vertical range. A few Saurians, and some Ophidians, especially of the family of 
Vipers, extend much farther north, and much higher up, along the slopes of the 
mountains, than any Chelonians. In the second place, it is known that the sea Tur- 
tles, the Chelonii proper, which constitute the lowest sub-order of the Testudinata, 
have a much wider range than the land and fresh-water Turtles, the Amydm. This 
fact is important in two different points of view: first, as corroborating the asser- 
tion, already made above, that the lower representatives of any comprehensive group 
have a wider distribution than its higher types; and secondly, as showing that the 
mediums in which the lower types dwell are frequently different from those which 
suit the higher ones. It is a fact, that though the Testudinata, as a whole, have 
a more limited geographical range than the other orders of Reptiles, the sea Turtles, 
which are unquestionably the lowest Testudinata, are by far more widely diffused 
upon the surface of the earth than either the land or fresh-water Turtles. They 
are common to all oceans, being found in the North and South Atlantic as well 
as in its warmest waters; in the Mediterranean, in the Indian Ocean, and over 
the whole range of the Pacific. Moreover, marine Turtles have been observed in 
northern latitudes, far beyond the range of other Turtles; they are, indeed, the only 
ones seen, and that but occasionally, along the northern shores of Europe and of 
Eastern Asia. It is not less characteristic, that these Chelonii, which are the lowest 
of the Testudinata, are at the same time all marine, while the Amydm, which con- 
stitute a higher sub-order, never live in the ocean, but only upon land, either in 
fresh water or upon dry land. 302 
AMERICAN TESTUDINATA. 
Part IL 
In the sub-order of Amydae, the same features which characterize the Chelonii 
obtain again, though within still more restricted limits. The aquatic Amydae have 
a wider range than the terrestrial; and while the lower representatives of the 
sub-order are fluviatile, the higher are terrestrial. The lowest Amydae, the Triony- 
chidae, have truly the widest distribution; for while in the Old World they are 
chiefly limited to the tropical fresh waters, in the New World they are only 
found within the temperate zone of North America, extending as far north and 
as high in the mountains as any other Turtles, indeed much farther north, and 
higher up, than any land Turtles, and even beyond the natural boundaries of the 
Emydoidae. The family of Chelydroidae is already much more restricted in its range, 
being limited to the temperate zone of the eastern side of the North American 
and of the Asiatic continents. The Chelyoidae, on the contrary, are circumscribed 
within the fresh waters of tropical South America; whilst the Cinosternoidae extend 
over the temperate parts- of North America, over Central America, and over the 
warmer regions of South America. The Ilydraspids, on the contrary, prevail in 
South America, and extend also to Southern Asia, to Africa, and to New Holland. 
The family of Emydoidae, which is, as it were, the central type of the Amydae, 
is the only one among the fresh-water Turtles which has representatives simulta- 
neously in North and South America, in Europe, in Africa, and in Asia, though 
the range of the individual species is very limited in this family also, much more 
so, indeed, than the species of the lower families of the aquatic Amydae, or 
those of the Chelonii. The highest Amydae, the Testudinina, or land Turtles, are 
the most limited in their range, if we contrast them with the whole number of 
fresh-water Testudinata, for they do not extend beyond the limits of the warmer 
parts of the temperate zone, while the aquatic Amydae are not only found in 
the tropical fresh waters, but also in those of the warm, and even of the colder 
parts of the temperate zone. It may perhaps seem unnatural, that I should 
thus contrast the Testudinina, which constitute only one family, with the many 
families of fresh-water Amydae; but it is just the object of physical geography 
to ascertain what are the natural relations between the physical conditions of the 
surface of the globe and the organized beings which live upon it. 
I shall enter into more details respecting the special distribution of the North 
American Testudinata, after I have considered more fully their generic and specific 
relations to one another. There is one more point, however, which deserves to be 
noticed in this connection. The Chelonii proper, which are the lowest, and at the 
same time the only marine Testudinata, are also the largest representatives of the 
whole order; next in size are some of the fresh-water Amydae, of the family of Che- 
lydroidae, which are very large, as are also some of the Testudinina. The average 
size of the fresh-water Amydae exceeds, nevertheless, that of the terrestrial ones, Chap. I. 
FOSSIL TURTLES. 
303 
though the smallest of all Testudinata are fresh-water species. But it must not 
be forgotten, that these belong to the temperate zone, while the largest land Turtles 
are exclusively tropical. Gigantic Testudinata, approaching the size of the largest 
land Quadrupeds, are known among the fossils. 
SECTION XVII. 
FIRST APPEARANCE OF TESTUDINATA UPON OUR GLOBE. 
Though the period of the first appearance of the Testudinata upon the surface 
of our globe has been a point of discussion among naturalists, even within the last 
few years, I do not intend to enumerate here the fossil representatives of this 
order, now satisfactorily known, nor even to compare the different Turtles which 
have existed, in former ages, in North America, with those now living. My 
object, for the present, is simply to point out the period at which this remark- 
able type of animals first made its appearance, and at the same time to show 
how important critical investigations are with reference to the affinities of fossil 
and living animals, and how utterly impossible it is to arrive at any general 
result respecting the order of their succession in time without such a close and 
careful study. Only five years ago, Sir Charles Lyell published a supplement to 
the third edition of his Manual of Elementary Geology,1 intended chiefly to sus- 
tain the view that Reptiles had existed much longer upon the surface of our globe 
than was generally supposed, and that the Chelonians in particular could be traced 
back to the Potsdam sandstone, that is, to the lowest stratified set of beds in 
which fossils had been found at all. The identification of these animals rested 
upon footprints which had been examined by Professor Owen, who published a 
description of these impressions early in the year 1851.2 This report has since 
gone the rounds of all the scientific and other periodicals, and is now repeated 
in almost every modern text-book of Geology and Palaeontology, though Owen him- 
self has recognized his mistake,3 and in the following year published his opinion, that 
1 Lyell's Manual of Elementary Geology. Post- 
script to the third edition, London, December 10th, 
1851. 
2 Description of the Impressions on the Potsdam 
Sandstone, discovered by Mr. Logan, in Lower Can- 
ada, Quarterly Journal of the Geological Society, 
London, 1851, vol. 7, p. 250. 
8 A few days after Professor Owen had read his 
first notice in London, an abstract of it was communi- 
cated to the American Association for the Advance- 
ment of Science, during its meeting at Cincinnati, 
May, 1851, which led to a discussion, in which I ex- 
pressed my conviction, based partly on physiological 
grounds, and partly on the examination of similar 
impressions, that they were the tracks of some palae- 
ozoic Crustacean, and not those of a Reptile. 304 
AMERICAN TESTUDINATA. 
Part II. 
these footprints " were not made by a Chelonian Reptile,1 nor by any vertebrated 
animal." About the same time, Captain Lambert Brickenden2 described foot-tracks 
from the Old red sandstone of Morayshire, which are also ascribed to Chelonians. 
Though I have not seen these fossil footprints, I have seen the impressions left 
by Turtles, upon soft mud, often enough to feel justified in saying that the Scotch 
foot-marks have not the remotest resemblance to the footprints of a Chelonian. 
These animals, when walking, stretch the legs on opposite sides of the body, in 
a diagonal position with reference to the body itself, so that the foot-marks of 
the fore foot of one side and those of the hind foot of the opposite side, form 
couples which alternate with the corresponding couples arising from the fore 
foot and the hind foot of the other side. No such succession is observed in the 
footprints described by Captain Brickenden. No more do the footprints from 
the Red sandstone near Dumfries, in Scotland, described by Dr. Duncan and by 
Dr. Buckland, and reproduced by the latter in his Bridgewater Treatise, resemble 
foot-marks of Turtles. 
Long before the publication of these different notices, the existence of Turtles 
in older geological formations had been asserted by Sedgwick and Murchison,3 who, 
upon the authority of Cuvier, had referred to the genus Trionyx a fragment of 
bone found in Scotland, in the slates of Caithness, which belong to the Old red 
sandstone formation. These remains I have shown, in my work on Fossil Fishes,4 
to be those of a very remarkable type of extinct Fishes, forming a distinct 
family, the Cephalaspides, and belonging to the genus Coccosteus. Kutorga has 
also described fragments of fish bones of the Old red sandstone, as belonging to 
the family of Trionyx.5 In his researches on fossil bones, Cuvier, finally, has 
referred to Chelonians several remains from the Muschelkalk, which were after- 
wards shown by Herman von Meyer to belong to the genus Nothosaurus. 
These are, as far as I know, all the instances in which the existence of Turtles 
in deposits older than the Jura has been maintained. Though introduced by the 
highest scientific authorities, there is not one of these alleged cases which stands 
a careful criticism. Neither the tracks of the Potsdam sandstone of Owen, nor 
1 Description of the Impressions of Footprints of 
the Protichnitis from the Potsdam Sandstone of Can- 
ada, by Professor Owen, Quarterly Journal of the 
Geological Society of London, 1852, vol. 8, p. 214. 
The geological description of Sir William Logan, 
which precedes, p. 199, gives the most minute account 
of the occurrence of these fossil footprints in Canada. 
2 Quarterly Journal of the Geological Society of 
London, vol. 8, p. 97. 
8 On the Structure and Relations of the Deposits 
contained between the Primary Rocks, and the Oolitic 
Series in North Scotland, by A. Sedgwick and R. I. 
Murchison, in the Transactions of the Geological So- 
ciety of London, 2d series, vol. 3. 
4 Monographic des poissons fossiles du vieux Gres 
Rouge, Neuchatel, 1844, 1 vol. 4to. p. 22. 
5 See the same Monograph, p. 91. These re- 
mains belong to the genus Asterolepis. Chap. I. 
FOSSIL TURTLES. 
305 
those of the Old red of Captain Brickenden, accepted by Lyell and Mantell, nor 
those of the Rev. Dr. Duncan, examined and described by Dr. Buckland, have 
the slightest resemblance to the tracks of any living Reptile, while the bones of 
the Devonian from Caithness, referred to Trionyx by Cuvier, and those of the 
same formation referred to the same genus by Kutorga, are really Fishes, and 
those of the Triasic period, described by Cuvier, are Reptiles of another order. 
The first genuine Testudinata known among the extinct representatives of the 
class of Reptiles, in past ages, belong to the oolitic series. 
It is self-evident, that the geologist who has neither the means nor the incli- 
nation to test critically how far any identification of fossils may be relied upon, 
must, at every step, be led to the strangest conclusions. What would be the 
direct inference, with respect to the plan of creation, to be drawn from the 
presence of unmistakable Turtles in the oldest fossiliferous rocks ? Of course, the 
conclusion would be that there is no kind of progressive order in the successive 
appearance of Vertebrates upon the surface of our earth, since the presence of the 
highest Reptiles would appear coeval with that of the oldest Fishes. But let it be 
understood that all the supposed cases of the occurrence of Reptiles prior to the 
Jura which have been quoted from time to time, cannot be relied upon, and are 
evidently mistakes, the whole question at once changes its aspect, and we see 
again an intelligible plan in the order in which organized beings have successively 
made their appearance upon this globe. 
The following diagram, made, so far as it has been in my power, with the 
same critical method with which I have scrutinized the case of Turtles, may give a 
more definite idea, not only of the time of the first appearance of Testudinata, but 
of their relations to their predecessors, their contemporaries, and their successors 
upon the earth.1 It shows conclusively, that the four great branches of the 
animal kingdom have had simultaneously representatives from the very beginning 
of the existence of organized beings. It shows further, that the law which 
obtains in the gradation and successive appearance of the Radiata, Mollusca, and 
Articulata is not the same as that of the Vertebrata. For while the classes of 
the first three branches appear all at the same time in the lowest fossiliferous 
rocks, with the sole exception of Insects, there is a decided gradation among the 
classes of Vertebrata. Among Radiata, we find simultaneously in the lowest 
rocks, Polypi and Echinoderms. The absence of remains of Acalephs in the 
oldest rocks is no objection to this assertion, when we remember how soft and 
1 In order to appreciate fully the meaning of this 
table, it would be well, while considering it in detail, 
to read section 7 of the first chapter, page 23, and 
also sections 21-28, from page 93 to 123, where many 
points are considered, which here are represented 
graphically. Comp, also Chap. 3, p. 181-187. 306 
AMERICAN TESTUDINATA. 
Part II. 
perishable their bodies are. The presence of well defined impressions of Medusae 
in the lithographic limestone of Solenhofen, specimens of which are preserved in 
the Museum of Carlsruhe, confirms the assumption that they occur everywhere, 
where Polypi and Echinoderms are found together. Among Mollusks, Acephala, 
Gasteropoda, and Cephalopoda are always found in close association. Among 
Articulata, this is also the case with Worms and Crustacea; Insects only appear 
at a somewhat later period. Whilst among Vertebrata, we find only Fishes, Sela- 
chians, and Ganoids in the lowest formations; next Amphibians, next Reptiles, 
next Birds, and last, Mammalia. 
TABLE, 
SHOWING THE PERIOD OF THE FIRST APPEARANCE OF THE TESTUDINATA COMPARED WITH THAT OF THE 
OTHER ANIMALS. 
Geological 
Periods. 
Radiata. 
Mollusca. 
Articulata. 
Vertebrata. 
Polypi. 
Acalephs. 
Echinoderms. 
Acephala. 
Gasteropoda. 
Cephalopoda. 
Worms. 
Crustacea. 
Insects. 
Myzontes. 
Fishes. 
Selachians. 
Ganoids. 
Amphibians. 
Reptiles. 
Birds. 
Mammalia. 
Present. 
- 
2 
- 
8 
4 
6 
Pliocene. 
Miocene. 
Eocene. 
Cretaceous. 
Jurassic. 
Triasic. 
Permian. 
Carboniferous. 
Devonian. 
Silurian. 
Cambrian, or Azoic.1 
1 The most natural limit between the Cambrian 
and Silurian periods seems to me to be the hori- 
zon at which animals and plants make their first 
appearance. 
The Table renders it unavoidable to refer notes 2, 3, 4, and 5 to the opposite page. Chap. I. 
307 
FOSSIL TURTLES. 
The classes adopted in this table are circumscribed according to the principles 
discussed in the first part of this work.6 I have nothing special to add with 
reference to the classes of Radiata, Mollusks, and Articulata; but it may be proper 
to state here, that the order of appearance of the classes of Vertebrata makes in 
favor of the subdivision of the Fishes into four classes. The Selachians, in par- 
ticular, differ so completely from the ordinary Fishes, that it is surprising they 
have not long ago been considered as a distinct class.7 In a palaeontological 
point of view, the early appearance of the Selachians has a deep meaning, when 
we consider how extensively the characters of the higher classes of Vertebrata 
(such as their few large eggs, which recall the true Reptiles and the Birds, and 
the placental connection of the embryo of some of their species, which recalls 
the Mammalia) are blended in their structure with embryonic features, (such as 
their cartilaginous skeleton and their branchial fissures,) whilst the Myzontes are 
purely embryonic. The Ganoids, on the other hand, stand in a special prophetic 
relation to the Reptiles proper;8 and their extensive reduction, at the time of the 
first appearance of the Fishes proper, is truly significant. 
2 The period of the first appearance of genuine 
Fishes is somewhat doubtful, and depends upon the 
appreciation of the true relations of the Leptolepids. 
If they are Ganoids, as I consider them, then the 
class of Fishes proper does not appear before the 
Cretaceous period. 
8 This is the period of the first appearance of 
Testudinata; at a time when neither genuine Birds 
nor genuine Mammalia existed. 
4 The presence of Birds in the Triasic period 
is only inferred from the numerous footprints found 
in the Red sandstone of the valley of the Connec- 
ticut, respecting the true characters of wrhich I have 
expressed my doubts elsewhere. As it is now 
known that the earliest representatives of higher 
types often exhibit characters common to them and 
to lower types, it seems to me probable that the 
first Birds were not so completely different from 
the other Vertebrates as the Birds now living 
are. Before the first appearance of genuine Birds, 
there may have existed bird-like Vertebrates, com- 
bining in their structure Reptilian and Mammalian 
characters, as we find early Reptiles combining Fish 
characters, and even anticipating, in some of their 
features, peculiarities that are afterwards charac- 
teristic of Birds and of Mammalia. The foot-marks 
of the Trias suggest such suppositions much more 
readily than the idea of a very close affinity to real 
Birds. For more details upon these tracks, see 
Hitchcock, (Ed.,) An Attempt to Discriminate and 
Describe the Animals that made the Fossil Foot- 
marks of the United States, etc., Mem. Amer. Acad. 
1848, vol. iii. p. 128, and Deane, (James,) Illustra- 
tions of Fossil Footprints of the Valley of the Con- 
necticut, Mem. Amer. Acad., 1849, vol. iv., p. 204. 
No Bird remains are known from the Jura. 
6 The presence, in the Jurassic period, of remains 
belonging apparently to the class of Mammalia, has 
long been known. But Owen for the first time 
set forth their true relations, in a paper published 
in the Transactions of the Geological Society of 
London, 2d series, vol. vi. Whether Microlestes of 
the Trias, described by Plieninger, belongs to the 
same type, is still questionable. If it is a Didel- 
phian, it would carry this sub-class one period lower 
down. It is curious, that nothing like them has thus 
far been found in the Cretaceous formation. So 
the age of Mammalia proper begins with the Eocene 
period, unless some recently described Cetaceans 
truly belong to the Cretaceous period. 
6 See Part L, Ch. 2, p. 145, and Ch. 3, p. 183. 
7 Aristotle alludes here and there to the Sela- 
chians in contradistinction to the Fishes proper. 
8 Comp. Part I., p. 116 to 118. 308 
AMERICAN TESTUDINATA. 
Part II. 
SECTION XVIII. 
SUB-ORDERS OF TESTUDINATA. 
The Sul-Order of Sea-Turtles - Chelonii, Opp} The sea is the home of these ani- 
mals. They swim freely, and sustain themselves in the water for any length of 
time without seeking the bottom or the shore for support or rest. They never go 
on land, except to lay their eggs, and then proceed only a short distance from the 
shore, moving slowly and in a very constrained way. They swim almost entirely 
by means of the front limbs; the other pair act independently, and are chiefly 
useful in aiding to balance the body and guide the general course. The fore- 
arm and hand form a sort of paddle, or rather a wing. These two wings are 
raised together, and also strike downward simultaneously; but the blow is not exactly 
vertical, the wings being carried forward as they rise, and approaching the breast 
when brought down. They descend farther below the body than they rise above 
it, and their motion is very similar to that of a Bird's wings; indeed, the animal 
may be said to fly through the water. On land, these animals still move the 
front limbs together, carrying them forward, throwing the weight of the body upon 
the elbows or thereabouts, and then pulling the whole toward them. 
The peculiar flying locomotion of this sub-order affects the general symmetry 
of the body very essentially in two ways: first, it makes it necessary that the 
bulk of the body should be carried forward near the wings, otherwise the animal 
could not control it; secondly, the force necessary to propel the wings requires 
a large muscular apparatus, and this takes much room, so that the fore part of 
the body (dividing the whole crosswise into two parts of equal lengths) far out- 
weighs the hind part, being in bulk in the proportion of two to one; the fore part 
is broad and high, the hind part descending and narrowing gradually. The humerus 
is very short, and the extensive surface of the wing arises principally from the 
blade, which is formed of the forearm and hand. This blade is long, broad, and 
thick at the base, thin along the inner margin, and pointed at the outer end; 
it is turned back at the elbow, and cannot be brought out in a line with the 
humerus, though it is capable of moving towards it and away from it through a 
long arc. The force and general direction of the blow is given by the muscles 
of the shoulder; but the surface presented is determined in a great measure by 
the rotation at the elbow, at the wrist, and within the hand, the blade being 
1 This sub-order was first recognized and char- 
acterized by Oppel, in the work quoted below, p. 
309. Compare also Sect. 2, p. 241, where the syno- 
nymes of the sub-orders are given, and Pl. I.-VI. Chap. I. 
SUB-ORDERS. 
309 
turned, now edgewise, now flatwise, to the resisting medium. The fore-arm is short; 
the radius is carried down and back under the ulna, and the inner side of the 
hand carried down with the radius. By this peculiar arrangement, the flat surface 
of the hand is more directly presented to the resistance of the water in the 
downward and backward flying blow. The fingers add the greater part to the 
length of the blade; they are very long, stiff, and fixed in their respective places, 
their only movement consisting in a slight accommodation to the turning of the 
whole blade. The muscles and skin form one continuous surface over the fingers, 
excepting the last joint of one or two of them, which, sometimes at least, pro- 
trudes, and has its protruding surface covered with a nail. The coracoid process is 
very long; the other bones of the shoulder apparatus short and stout. It is 
necessary to the flying locomotion of this sub-order that the wings should have a 
free sweep by the front end of the body, and that nothing should hinder them 
in rising and descending or moving backward and forward; hence the shield 
cannot project forward above or below, and the humerus carries the elbow, in all 
its positions, beyond it. Again, as the humerus is so short, and the blade so 
long, the front limbs cannot be brought round before the body; but, when at rest, 
the blades hang down, or are placed beside or upon the outer edges. Although 
the front limbs are the principal locomotive organs, and are essentially wings 
in all their operations, there is yet one marked structural difference between 
them and the wings of a Bird; for with the Turtles the humerus reaches 
forward, and the forearm and hand are turned backward in one line from the 
elbow, whereas with the Bird, the humerus reaches backward, the forearm for- 
ward, and the hand again backward, the main surface of the wing being in the 
angle of the forearm and hand, instead of being, as in Turtles, in the angle of 
the humerus and the limb below. The pelvis and hind legs are very small. The 
legs, as was said above, do not move together with the wings, and they take little 
part in locomotion beyond aiding to balance and guide the body. The femur 
and leg are short, and the toes also short, compared with the fingers, but they 
form the greater part of the whole blade below the knee. The leg and foot 
are formed into a paddle, much smaller than the blade of the front limbs, and 
broadest near the outer end. Below the knee, this blade is generally turned back- 
wards ; but it moves through a long arc back and forth, and may even be brought 
out upon a line, or nearly on a line, with the femur. The paddles often strike 
directly downwards, so that the plastron cannot extend under them, and is very 
small under the pelvis. 
The neck is short and little flexible, so that the head is not withdrawn under 
the carapace; instead of this, it is protected by a very large development of the 
post-frontal, parietal, jugal, and mastoid bones, making a bony arch over the whole 310 
AMERICAN TESTUDINATA. 
Part II. 
head back of the eyes, and projecting somewhat over the neck, entirely covering 
the temporal muscles above. Thus neither head nor limbs can be withdrawn 
into the shield, and the front limbs cannot even be brought round before the 
body, but they can all be drawn back somewhat. So the method of protect- 
ing the extremities and the head, which is so fully developed in the other sub- 
order, and is so characteristic of the order, is here but just begun. The shield 
itself is here much less developed than in the other sub-order. In one family, 
the Sphargididse, it is little more than a broad girdle, encircling the thorax and 
abdomen; its bony part does not rest upon the ribs, and has no marginal 
rim. In the other family, the Chelonioidae, the shield is somewhat larger, cover- 
ing the pelvic region above; but still the front limbs, including the shoulders, are 
free and exposed, and so also are the hind limbs below, including the hips. 
Although the bony derm rests upon the ribs, their union never becomes so inti- 
mate as in the other sub-order, and the plastron is but imperfectly ossified and 
rather loosely connected with the carapace. Thus we find the most prominent 
characteristic features of the order least developed in this sub-order; and if we 
add to this the habitat, the mode of locomotion, the paddle-like structure of the 
limbs, the reduced state of the hind pair, the want of specialization in the neck 
vertebrae, and the unsymmetrical relations of the two ends of the body, we can- 
not hesitate to consider this group as the lowest of the Turtles, and to recog- 
nize a kind of gradation in rank between them and the Amydm. But here, 
in this lowest group, where the characters of the order are least prominent, we 
find features of form and structure which remind us of animals higher in the 
series, and belonging to another class. The mode of locomotion, the form and 
structure of the locomotive apparatus, the great preponderance of the fore part 
of the body, the bill-like jaws, the overlapping of the scales in some, as in 
Penguins, are all characters which belong to the class of Birds, and are there 
only carried out to their fullest development. 
The Sul)-Order of Fresh-water and Land Turtles - Amyd.e, Opp} The habitat is 
various. Some species spend nearly all their life in the water, some live partly 
under water and partly on dry land, and some entirely on dry land; yet none 
are entirely aquatic, none remain for any great length of time in the water with- 
out seeking the bottom, nor can they swim unsupported for a long distance. When 
in the water, they remain usually at the bottom, either at rest or moving along 
over it. They seldom swim freely, except when they rise to the surface or descend 
to the bottom. So, in fact, they dwell principally upon land, sometimes under the 
1 Like the sub-order of Chelonii, that of Amydae 
also was first recognized and characterized by Op- 
pel, in his classical paper, Die Ordnungen, Familien, 
u. Gattungen der Reptilien, Munchen, 1811,1 vol. 4to. Chap. I. 
SUB-ORDERS. 
311 
water, and sometimes in the open air. The difference between these two conditions 
does not acquire much importance with reference to the characters of the sub-order, 
as will be seen from the fact that, in the family of Emydoidae, one genus at least 
never goes into the water, while several genera live the greater part of the time in 
water, and there is a series of intermediates. These differences affect the structure 
and symmetry in a smaller degree, and are not to be compared in importance with 
those which distinguish the sub-orders; they do not essentially alter the mode of 
progression. 
The locomotion is entirely different from that of the sea Turtles. It no longer 
takes place by a Hying, but by a walking motion; the weight is not thrown 
upon the front limbs, but is almost equally supported by both pairs; the front pair 
are not carried up together, and then brought down simultaneously, but they alter- 
nate with one another, as do also the hind pair; the front legs of one side 
move with the hind legs of the other side, so that the two pairs act in concert; 
further, they move back and forth below the carapace, in a diagonal plane 
between the perpendicular and the horizontal diameter of the body. The two 
pairs are nearly equally developed, as also are the pelvis, and shoulder apparatus. 
As the bulk of the body is no longer thrown upon the front limbs, and as the 
muscular apparatus of the two pairs occupies about equal space, there is no such 
contrast between the two ends of the body as exists in sea Turtles. This 
mode of progression, and the consequent symmetry, allow greater development of 
the bony shield than can take place with the other sub-order. As the fore limbs 
are not raised high up, when moving, the carapace may be extended forward 
without interfering, and as they are not brought far down crosswise over the body 
toward one another, the plastron may be broad between them. The carapace is 
always broad above the pelvis, and covers all that part of the body, and the hind 
legs, when they are at rest; the plastron is sometimes broad under the pelvis 
and the hind legs. 
The limbs are never reduced to paddles or wings; the feet are always distinct 
from the legs; the articulations at the wrist and ankle joints allow distinct move- 
ments, and not merely a kind of yielding to the turning of the whole limb, below 
the elbow, as with the sea Turtles. In the feet of this sub-order, the toes never 
have the great length which distinguishes them in the wings and paddles of sea 
Turtles. When the foot is adapted to walking on dry land, the toes are short- 
ened, and the whole concentrated, and their joint with the leg above is rather 
stiffened; when it is more adapted to swimming, there is greater freedom of 
motion at the wrists and ankles, and between all the bones of the feet below; 
the phalanges are prolonged, and the toes joined by a broad web, capable of 
being spread far apart and closed together. When the blow is struck, a broad, 312 
AMERICAN TESTUDINATA. 
Part II. 
webbed surface is presented to the water, and when the foot is withdrawn for 
another blow, the web is folded; - a very different way of controlling the surface 
presented to the resistance of the water from the turning of a stiff blade, now 
edgewise, now flatwise, which takes place with the sea Turtles. The limbs, thus 
jointed and proportioned, can always be withdrawn under the carapace, the front 
pair before, and the hind pair behind, the main bulk of the body; the neck 
is always retractile enough to allow the head to be withdrawn partially, and 
generally completely, within the shield; and we nowhere find the temporal muscles 
protected by such a very broad bony arch as exists in the sea Turtles. 
Here, then, those features which are most peculiarly characteristic of the order 
of Turtles, namely, the protection of the body by the shield, and the withdrawing 
into the shield of the head and neck, and limbs and tail, are most fully devel- 
oped. This sub-order occupies clearly a higher rank than the other; the equilibrium 
of the body, the higher development of the limbs, the cooperation of both pairs 
in the progression, the greater specialization of the neck vertebrae allowing the 
head to be withdrawn under the carapace, the nature of the habitat, and the 
higher degree to which the characters of the order are carried, - all these features 
assign to the Amydae a rank superior to that of the sea Turtles. In this higher 
group, the Bird characters, which are so prominent in the sea Turtles, yield to 
the characters of a higher class. The equal development of the two pairs of 
limbs, their full cooperation, the walking locomotion, the elevation of the body 
free from the ground while walking which takes place with most of them, and 
the general symmetry of the body, are characters which remind us of the class 
of Mammals. And the analogy is the more striking when we remember that this 
is the first instance, in the series of Vertebrata, of real walking, unless the running 
of some toads be considered as such; for the Salamanders, the Lizards, and the Croc- 
odiles move partly by means of the vertebral column bending and carrying the 
legs forward, now on one side and now on the other. These Mammalian charac- 
ters may be not so striking here as the Bird characters are with the other group, 
for the class of Reptiles is further removed from that of Mammals than the 
Birds; still the analogy is too complete and too clear to be accidental, or to be 
passed over in silence. One marked difference between the locomotion of these 
Turtles and that of Mammals is, that in the former the knee and elbow joints 
open in the same direction, whereas in Mammals they bend in directions opposite 
to one another. 
The characters of the Chelonii and Amydse show these two groups to be 
sub-orders, and neither families nor orders proper, as they partake of the features 
of orders, without extending to the whole structure of all the different systems 
of their organization. Chap. I. 
CONCLUSIONS. 
313 
SECTION XIX. 
CONCLUSIONS. 
I have attempted in the preceding sections to illustrate, so far as it was in 
my power, the characters of the order of Testudinata, more with the view of 
ascertaining what are ordinal characters, than in the hope of drawing a complete 
picture of the whole order. Consulting the leading works upon this subject, I 
have found that all original investigators agree in presenting, as characteristic of 
this type, the same kind of characters as I have mentioned above, and nearly in 
the same way, though perhaps they have not aimed so directly, and with the 
same care, as I have done, at admitting only such anatomical features as are 
truly characteristic of the whole order, and excluding every feature which occurs 
in other representatives of the class. If I have succeeded in this attempt, and if 
the characters presented above are truly those of the order of Testudinata, it follows 
that ordinal characters are essentially anatomical characters, and not what are 
commonly called zoological characters. They are borrowed from the peculiar com- 
plication of the anatomical structure of the class of Reptiles, so that this type 
furnishes direct evidence of the correctness of the definition of orders given in 
the first part of this work,1 where it is stated that orders are natural groups, 
characterized by the degree of complication of their structure. It follows, there- 
fore, that, to characterize orders correctly, we must compare their anatomical struc- 
ture with that of the other orders of the same class, as I have done above,2 
and that, by this comparison, we ascertain the relative rank of this kind of natural 
groups; whereas in characterizing families, we consider the structure with reference 
to the form of the animal; and in characterizing classes, we illustrate, in a general 
manner, the ways in which, and the means by which, the plan of their respective 
branches is executed. 
The characters of classes, like those of orders, are anatomical; but in charac- 
terizing a class, we consider the nature of the different systems of organs which 
constitute their living frame, we investigate the relations of their systems of organs 
to one another, their respective functions, etc., and not the various degrees of 
complication which they may exhibit in these combinations, for such complications 
constitute ordinal characters. If this is correct, and true to nature, it follows 
further, that such a distinction as is often made in Natural History, between 
1 See Part I., Chap. 2, Sect. 3, p. 150. 
3 See Part IL, Chap. L, Sect. 3, p. 252. 314 
AMERICAN TESTUDINATA. 
Part II. 
anatomical and zoological characters, is not correct, in the sense in which it is 
generally understood; but that so-called anatomical characters are either characters 
of the classes or of the orders, and, to some extent also, of the families, while the 
so-called zoological characters are more properly generic or specific characters, and 
the features generally considered in what is now called Philosophical Anatomy, and 
in Morphology, are mostly characters of the great types or branches of the animal 
kingdom. The separation of Comparative Anatomy from Zoology, as a distinct 
branch of science, is therefore only justifiable in so far as the proper meaning 
of those peculiarities of the structure of animals which characterize classes or 
orders, or families or genera, have not yet been satisfactorily ascertained ; but I 
look forward to the time when the more comprehensive groups of the animal 
kingdom shall be illustrated in our zoological works with that fulness of struc- 
tural illustrations which is now generally supposed to belong to anatomical works 
only, and with that searching care which alone can insure a proper discrimination 
between organic features of different kinds. 
Such a method will, in due time, relieve our science of all the exaggerations 
respecting homologies, with which it has of late been incumbered. As soon as it 
is understood, that the great branches of the animal kingdom are characterized by 
different plans of structure, and not by peculiar structures, we shall have fewer of 
those unsuccessful attempts to force every peculiarity of every type into a dia- 
gram, by which, renouncing almost entirely the study of the wonderful combina- 
tions of thought which are manifested in the endless diversity of living beings, 
authors substitute for them a dead formula of their own making. Having once 
understood, for instance, what constitutes the peculiar plan of Vertebrates, we shall 
be prepared to find it executed in a variety of ways and with innumerable com- 
plications, and we shall no longer try to force the framework of a Fish into a Pro- 
crustean bed, to which we may reduce at the same time all other Vertebrates, with 
Man. When the axis of the body consists of a simple dorsal cord, we shall be 
willing to acknowledge that it is not to be considered as an articulated backbone; 
when the skull-box consists of a continuous cartilage, that it is not to be artificially 
divided into isolated parts; and, when there are no limbs at all, we shall not 
assume that they exist potentially in the same degree of complication as in animals 
more favorably endowed. And, let it not be supposed, that such a sobriety of 
views excludes general comparisons; it only withdraws them from the field of 
fancy to the rich field of life. 
Suppose, for a moment, that we should attempt to homologize the different 
parts of the solid shield of a Turtle with the complicated system of muscles which 
intervene between the ribs and the skin in the trunk of other Vertebrates, or 
assume, perhaps, that the few scales which cover their back are to be considered Chap. I. 
CONCLUSIONS. 
315 
as arising from the confluence of the innumerable hairs or feathers which cover 
the backs of Birds or Mammalia, - would this not be doing, for the muscular 
system or for the external coverings, what is now doing, on so broad a scale, for 
every isolated point of ossification in the skeleton ? Let us rather be satisfied 
to recognize the fact, that Vertebrates have a plan of their own; that this plan is 
carried out in one way for Fishes, in another for Reptiles, in yet another for Birds, 
and again in another for Mammalia. It is true, grand traits of resemblance pre- 
vail through all, showing that the same thought is variously expressed in these 
different classes, and that this thought has found utterance in an endless diversity 
of distinct beings; but this resemblance lies chiefly in the unity of the conception, 
and not in the similarity of the execution. The various complications introduced 
in this execution constitute the typical peculiarities of the orders, while the forms 
in which they are inclosed constitute the typical peculiarities of the families, and 
the finish of the execution constitutes the typical peculiarities of the genera, while 
the relations to one another, and to the surrounding world, of the living individ- 
uals in which these thoughts are manifested, generation after generation, constitute 
the typical peculiarities of the species. Then, and then only, shall we grasp 
at the same time the grandeur of the conception of the plan according to 
which the animal kingdom is framed without losing sight of the admirable com- 
plication of its execution, and the infinite variety of conditions under which life 
is maintained. 
There is hardly any other type in the whole animal kingdom, in which the 
direct intervention of thought, as the first cause of its characteristic features, can be 
so fully and so easily illustrated as in the order of Testudinata. In the first place, 
these animals are so peculiar in their form and in their structure, that they strike, 
at first sight, every observer as belonging almost to another creation. They have 
been represented as inverted Vertebrata; and the peculiarity in the position and 
connection of their limbs has been so magnified, even to the rank of a class charac- 
ter, that very special conditions would seem necessary to their existence; and yet 
they are so extensively scattered upon the whole surface of the globe, among other 
animals of entirely different form and structure, upon land, in the fresh waters, and 
in the ocean, that, unless it can be shown that, besides its known properties, matter 
possesses also a turtle-making property, it must be granted that there are special 
thoughts expressed both in their structure and in their forms, and that the plan to 
which they belong, notwithstanding their striking differences, must have been devised 
and executed by a thinking being. In the next place, the different representa- 
tives of this order are allied to one another in such a manner, that every feat- 
ure of their organization appears to have been minutely considered; for, while 
some of their genera are closely linked, and constitute extensive families with 316 
AMERICAN TESTUDINATA. 
Part II. 
numerous species, other families are small, and their representatives more remotely 
allied and fewer in number; and, while some are limited in their range, others have 
the widest distribution, so much so indeed, that even those peculiarities of their 
existence which may seem the most trifling appear to have been devised with 
the same thoughtfulness and the same providential care as their most important 
general characteristics. It is, however, in the mode of their embryonic develop- 
ment, that Turtles show, most directly, the thoughtful connection which may be 
traced among all their peculiarities. For, while the young embryo Turtle exhibits, 
at some period of its life, the closest resemblance to other Reptiles, and while still 
younger, even to other Vertebrata, as soon as its Turtle characters begin to appear, 
nothing can be more surprising, or more attractive to watch, than the manner in 
which the peculiarities of the Amydae and Chelonii proper, and those of their 
different families, are successively blended and specialized in the periodicity of their 
exhibition, in their prevalence, in their transformation, and in their final growth. 
It seems almost as if we were allowed to penetrate into the sanctum of the great 
Artist, and could behold him so combining his thoughts as to produce a variety 
of master-works, in this case all representing the same idea, but each in a pecul- 
iar way, and at last endowing them with life for ages to come. 
The nature of these combinations, as characterizing the different families of 
Testudinata, will be illustrated in the following chapter. CHAPTER SECOND. 
THE FAMILIES OF TESTUDINATA. 
SECTION I. 
GENERAL REMARKS UPON FAMILIES. 
For many years past, naturalists have extensively indulged in the practice of 
separating, as natural divisions, any group of genera, or even single genera, which 
appeared to differ strikingly from other genera, and of calling such divisions, 
families, without apparently caring to ascertain upon what characteristics they 
were founded; nay, frequently without even assigning to them any characters at 
all, remaining for the most part satisfied with naming such families.1 It is, how- 
ever, not enough to select some prominent genus, and give to it a patronymic 
ending, in order to establish the right of any natural group to be considered as 
a family. The result of this practice, as it now lies before us, has been to 
incumber the nomenclature of Zoology with innumerable names ending in idee 
or ince. For, regardless of every question of priority, the names of families and 
sub-families should end in that way, according to certain writers. 
As no advantage can be derived, from such a method, to the real advance- 
ment of science, I have proceeded upon an entirely different plan in this work. 
After a most minute and careful comparison of all the Testudinata I could obtain, 
and having made myself familiar, as far as I could, with all their features, I 
have arranged them, according to their different degrees of relationship, into as 
many natural groups as I could recognize, and then only attempted to find out 
1 Naturalists who in no way deserve this impu- 
tation will pardon me if, to avoid useless personal- 
ities, I allude to the prevailing evil, without men- 
tioning names. A mere glance at my " Nomen- 
clator Zoologicus" will show to what extent this 
method of making families has been carried. 318 
AMERICAN TESTUDINATA. 
Part II. 
what was the real value of all these divisions. Trusting, in a measure, to the 
principles discussed in the second chapter of the first part of this work, I soon 
ascertained which of them exhibit generic characters, and which were to be con- 
sidered as families. I may well add, that I had also the gratification of finding 
that the natural groups, which 1 had thus practically circumscribed, afforded new and 
additional evidence of the correctness of the general principles ascertained before 
by a more extensive study of other classes. This direct confirmation of the gen- 
eral views there expressed shows plainly that these principles are likely to be of 
immediate practical use in the special investigation of any type of the animal 
kingdom, and may particularly assist zoologists in finding out the prominent char- 
acters of any kind of natural groups of animals. 
In the following pages, I have attempted to show how, according to these 
principles, families ought to be characterized. It will be seen, I hope, that, though 
it is easy to acquire satisfactory evidence that families are distinguished one from 
the other by distinct forms, it requires the most careful comparison to discover 
what are the structural elements which constitute these different patterns. And if 
this be so, it must be obvious, that such investigations necessarily lead to inter- 
esting results respecting the meaning of the structural differences which distinguish 
them. For my own part, I have already satisfied myself that in this way much 
can be learned of the habits of animals, the mode of life being in direct rela- 
tion to the form of the animal. More than once already has the direct obser- 
vation of the habits of our Turtles confirmed what the study of their form had 
at first only led me to suspect. 
The essential elements of the form of Testudinata, as far as the body is con- 
cerned, are, first, the curve of the back, following the line of the vertebral column, 
and its relation to a similar line along the middle of the lower surface; secondly, 
the outline of the outer edge of the shield, in its relation to the height of the 
carapace, and the depth of the lower part of the body; thirdly, the connection 
of the upper and the lower surface of the body, as determined by the lateral 
curves of the carapace and the plastron; fourthly, the outline of the plastron in 
connection with the openings through which the head, the limbs, and the tail are 
protruded between the upper and the lower parts of the shield; fifthly, the rela- 
tion of the bulk of the body with reference to the longitudinal axis. Next to 
these elements, the form of the neck and head affords excellent characters, as 
well as the form of the limbs, the relations of the front and hind pair, the 
articulation of their joints, and especially the form of the feet, the mode of con- 
nection of the toes, and the manner in which they act upon the medium of 
resistance when the animal is in motion. 
It has already been stated above, that though orders form necessarily progres- 319 
Chap. II. 
FAMILIES OF TESTUDINATA. 
sive series as they are characterized by the degrees of complication of their 
structure, other kinds of groups may stand higher or lower, when compared with 
one another.1 This is strikingly the case with the families of Testudinata, between 
which there is a marked gradation. Their respective standing is even so easily 
ascertained, that, ever since these animals have been divided into families, all her- 
petologists have arranged them in the same progressive series, beginning with the 
marine Turtles as the lowest, and ending with the land Turtles as the highest, 
while they all assign to the fresh-water Turtles an intermediate position between 
the two other groups. It is true, as far as the marine Turtles, on one hand, 
and the land and fresh-water families, on the other hand, are concerned, the 
relative position of these two groups is determined by structural features, which 
constitute sub-orders; but the gradation of the families is not limited to the 
relative standing thus assigned to them, for even the families of the Chelonii, 
and those of the Amydae, stand higher or lower among themselves; and within 
these narrower limits the gradation is no longer determined by the complication 
of their structure, but chiefly by peculiarities in those features which essentially 
characterize the families, namely, the forms. Chelonii, compared with Amydae, have 
lower forms; the form of the Sphargididae is made up of elements of an inferior 
order to that of the Chelonioidae; the form of the Trionychidae is simpler in 
its essential elements than that of the Chelyoidae, or that of the Chelydroidae 
and of the Cinosternoidae, in which last three families are preserved through life, 
elements of form which recall the characteristic features of the Chelonii, but 
which mostly disappear in the first years of life in the Emydoidae. In many 
respects the form of the Emydoidae approximates already that of the Testudinina, 
to which the highest rank undoubtedly belongs, on account of the higher sym- 
metry of the body. 
This progressive series of the families of Testudinata, as far as it is based 
upon their form, is not inferred simply from a vague estimate of the gradation 
of these forms, as they appear in the adult, but rests upon a direct comparison 
of the metamorphoses of the young, all of which undergo most remarkable 
changes in their form. These changes are the more instructive, as they consti- 
tute a connected series, when they are compared at certain stages of the growth 
in different families, and yet they lead, in the end, in each family, to the 
development of a typical pattern characteristic of the family. Starting from a 
common type at an early embryonic period, the form is gradually modified to 
a certain degree, in one family, before it assumes its typical characters; in another 
family the same primitive type diverges in another direction, and then assumes 
1 See Part L, Chap. 2, Sect. 3, p. 152-154. 320 
AMERICAN TESTUDINATA. 
Part II. 
its typical characters; while in a third family the progress leads in a still different 
direction, and ends in another typical form; etc. And yet, in no one instance, can 
these characteristic patterns be considered merely as resulting from an arrest in the 
development of one continuous series. On the contrary, they are evidently mod- 
ifications of one fundamental idea, expressed in various combinations of forms, which 
are so linked together, that it is only by an abstraction on our part that their 
connection may be ascertained, as it is only to an abstract conception that their 
origin and their combinations can be referred. If this be so, - and the sequel 
will, I trust, furnish satisfactory evidence that this is the only true view of the 
case, - it follows, that the different patterns which characterize the different families 
of Testudinata were devised, as the forms in which the structure of these animals 
were to be clothed, before they were called into existence. The various relations 
and the close connection which exist between these forms show further that their 
combinations were so considered beforehand, that when brought into existence 
they should constitute not only a regular series, but also a perfect system. In 
other words, the very outline of these animals, humble and low as they are, 
proclaims as loudly as the grandest features of nature, the direct intervention of 
a thinking Mind in their creation. 
SECTION II. 
THE FAMILY OF SPIIARGIDIDjE. 
The genus Sphargis, which alone constitutes this family, is now generally 
referred to the family of Chelonioidse by modern herpetologists, though for some 
time it has been considered as a distinct family1 by the ablest zoologists. In a 
1 It is a fact worth noticing, that no modern her- 
petologist has maintained the family of Sphargididae, 
though it was, at first, generally adopted as a natural 
group. This is, no doubt, owing to the looseness of 
the views now prevailing respecting classification. 
In similar cases, the objection is constantly urged, that 
a distinction is not necessary because the genera are 
so few. It may be useless, it is true, if it leads to 
nothing beyond the introduction of a new name into 
the system ; but if the distinction is based upon an 
accurate knowledge of the real standing of any sin- 
gle species exhibiting genuine family characters, then 
it must be adopted, not because it may appear con- 
venient, but because it exists in nature. I trust I 
shall show that this is the case with Sphargis. The 
first author who distinguished this genus from the 
other Chelonii, as a family, is J. E. Gray, who calls 
it Sphargidae, (Ann. of Philos. 1825,) though I think 
it ought to be written Sphargididje, in accordance 
with its etymology. Th. Bell adopted it in 1828, 
(Zool. Journ. Vol. 3,) and so does Fitzinger in his last 
work, (Syst. Rept. 1843,) changing, however, the name 
to DermatochelyDuE ; but since 1844 Gray unites 
it again with the Chelonioidse. Canino considers it Chap. II. 
THE SPIIARGIDID2E. 
321 
theoretical point of view, it is of the utmost importance to know that an iso- 
lated genus may constitute a distinct family, because such a fact shows how futile 
and artificial the efforts of those naturalists must be, who aim at establishing the 
utmost equality between groups of the same kind. Here we have a natural fam- 
ily, not only with a single genus, but perhaps with a single species, or, at the 
utmost, numbering two or three species, while there are other families, in which the 
genera may be counted by tens, and the species by hundreds. 
The form of the Sphargididae may be compared to a flattened cone with angu- 
lar sides, to which are appended in front a large head with a pair of larger 
naked paddles, and behind, a smaller pair of very broad rudders. 
The body is broadest about the arch of the second pair of ribs, where the 
carapace and plastron first unite, and narrows gradually from thence backwards 
to near the arch of the seventh pair of ribs, where the union of the carapace 
and plastron ends. The portion of the vertebral column which is fixed descends 
gently from the neck to the sacrum. Thus, that part of the body which is 
entirely encircled by the shield forms a truncated cone with its base turned 
forward. This cone is the more symmetrical, because the body is deep below 
the plane of its outer edge and not so extensively flattened as in most Turtles, 
but tapering downward, so that the median horizontal flat surface of the plas- 
tron is quite small. The shield fits close to the body above and below, and 
assumes the same conical form. The carapace, after passing over the thoracic 
and abdominal regions and separating from the plastron, suddenly grows narrow 
much faster, leaving the hind legs almost entirely exposed, but covering the 
sacrum with a narrow arch, and coming to a point over the tail. In front also, 
from its union with the plastron forward, the carapace narrows fast, but its front 
end is truncated; the margin of the sides and end of this narrowed part, which 
is turned rather sharply downward, are deeply concave, leaving the shoulders 
and neck much exposed. The plastron narrows constantly from where it first 
unites with the carapace to where it again separates from it, then narrowing still 
faster it comes to a point under the pelvis, leaving the hind legs and tail 
entirely exposed from below. It reaches forward, between the front limbs, but a 
short distance, and is there much narrowed; the front end of this narrowed 
part is nearly straight, but the sides are concave. Thus, the hard dermal shield 1 
a sub-family under the name of Spiiargidina (Saggio 
An. Vert. 1831.) The name of Sphargidse having 
the priority as a family name, though it is now re- 
jected by its own author, there arises an interesting 
question of nomenclature in this case, respecting the 
authority under which it shall be quoted henceforth. 
My opinion is, that, in spite of Gray himself, it should 
be referred to as Spiiargididje, Gray; notwith- 
standing even the alteration in the spelling. 
1 See Chap. 1, Sect. 5, p. 263. 322 
AMERICAN TESTUDINATA. 
Part II. 
is here little more than a broad girdle encircling the thorax and abdomen. The 
carapace has no sharp distinct marginal rim, but curves round over the outer 
edge and meets the plastron somewhat under the body; this curved outer edge 
rises constantly backwards. 
The carapace is strengthened by several longitudinal ridges, the most prominent 
of which is along the middle of the back; it is low and small at the front end, 
but grows higher and broader backward, until just over the sacrum it includes 
the whole width of the carapace, thence it lowers to the hind end, making this 
narrow, unsupported part of the shield much firmer than it would be if it was 
Hat on each side. Beginning at the angle of the truncated front end is another 
ridge, highest at the front end and diminishing backward, so that near the front 
end the two together render the top of the body nearly flat; but over the pelvis 
they change the curve of the surface but little. There are two more pairs of 
ridges outside, but they are quite small, and the lowest one little more than a 
row of bony nodules. The dermal shield, as in all Turtles, rests upon the vertebral 
column of the thoracic and abdominal regions, upon the ribs, upon the isolated 
true bone above the lower neck vertebrae, and upon the true bones of the ster- 
num. Over all these is wrapped a thick layer of coarse fibrous corium.1 In the 
carapace, this fibrous corium is protected and stiffened by an overlying sheet of 
bony pavement. This pavement2 nowhere rests upon or touches the true skele- 
ton ; it is perfectly continuous, without any other suture than those of its pave- 
ment-like structure, and without intervals above the ends of the ribs. This bony 
sheet curves with the carapace at its lower edge, but does not extend over the 
plastron. The ridges of the carapace, spoken of above, are made by angles in 
this sheet, filled up below by an increased thickness of the corium, but the lower 
surface of the latter has no corresponding depressions. Along each of the ridges 
is a row of nodules. In the plastron, the thick layer of fibrous corium is not at 
all protected by a bony sheet, and has no bony derm, excepting some rows of 
nodules; these rows are somewhat irregular, but there are, in general, five of 
them, a double one along the middle, and two single ones on each side. The 
corium is supported on its inner surface by the true bones of the sternum, of 
which there are four pairs; these are long, narrow, and arranged in a contin- 
uous row, encircling the flattened, horizontal surface. The foremost pair meet 
between the fore legs, and at their meeting are broad and strong; they spread 
apart backward, and overlap the outside of the second pair; the latter send out 
a process behind each shoulder; the second and third pairs extend the whole 
length of that part of the plastron which spreads entirely across the body, and 
1 See Chap. 1, Sect. 4 and 5, p. 256 and 263. 
2 See Chap. 1, Sect. 5, p. 264. Chap. II. 
THE SPIIARGIDIDJE. 
323 
the fourth pair meet at their hind ends under the pelvis. So we have an 
irregular ellipse of true bone, narrowed backward. This ring does not touch the 
ribs. The ribs are broad and flat, firmly supported and kept in position by 
the corium resting upon them. The first pair is free from the second, and so 
is the tenth from the ninth. The ninth extends back by the side of the pelvis, 
and thus strengthens the narrow end of the carapace. The specimen examined 
has only some of the neck vertebrae preserved, among which is the last; this 
has very little motion at the joint with the first dorsal vertebra. There are 
no scales on any part of the skin; at least, there are none on the skin of the 
only genus thus far known to belong to this family. 
The skeleton is light; the shield narrow and small in proportion to the size of 
the animal, and so placed with reference to the limbs as to be as little cum- 
bersome as possible; the surrounding thick layer of corium is filled with fat; the 
body is rounded, and the wings and paddles are large and free. These characters 
seem to indicate that the animal travels far and fast. This assumption would cer- 
tainly be justified, if it can be shown, as I shall attempt to do,1 that the speci- 
mens of Sphargis coriacea, observed in Europe, had travelled across the Atlantic 
from the coasts of North America. 
The head is high, short, and very broad at the hind end. As in the other 
members of the sub-order of Chelonii, the parietal, postfrontal, jugal, temporal, and 
mastoid bones are so extended as to form one continuous bony roof over the 
whole head back of the eyes, protecting the temporal muscles, and projecting 
somewhat back over the first neck vertebra?. In Sphargididss the parietal bones 
are almost exclusively devoted to the formation of that arch, as they enlarge the 
cavity of the brain-box only by a depression in their thickness, and a sulcus formed 
by two low ridges, and do not reach down to the floor of the skull, the upper 
occipital bone extending entirely across the brain-box under them. The temporal 
bones are small, and reach outward, so as to add rather breadth than length to 
the bony arch, thus making more room for the temporal muscles. The lower 
edge of the temporal and jugal bones, at their meeting, is deeply concave, thus 
allowing a broader attachment of the muscles for the lower jaw, and leaving 
them here somewhat exposed. The floor of the skull is carried far forward, con- 
siderably beyond the end of the roof. The prefrontals do not extend beyond 
the frontals, but the front edges of both make the front end of the top of the 
skull; the roof formed by them does not extend more than half way over the 
nasal cavity. The os quadratum descends low down, and carries the articulation 
of the jaws far below the general level of the floor of the skull. The outer 
1 See, below, Chap. 3. 324 
AMERICAN TESTUDINATA. 
Part II. 
surface of the intermaxillaries retreats backward from its upper to its lower edge; 
their inner edges separate about half way down from the nasal opening, and slant 
outward to the suture with the maxillaries, so that a deep, angular depression 
is included by their lower edges; the maxillaries too have a deep depression near 
the suture with the intermaxillaries, so that near this suture the alveolar margin 
forms a long, sharp, tooth-like projection. The alveolar margin of the upper jaw 
is sharp all round, except the lateral notches in front, which have a rounded edge. 
The horizontal part of the alveolar surface is narrow, forming a mere ridge at the 
front part, but it grows wider backwards. At the front end it rises steeply and 
high up. The palatines do not project over the vomer so as to form a broad 
roof below the palate proper, as in the Chelonioidm, and on that account the 
passages from the nasal cavity to the mouth open directly downward. For the 
same reason, the fleshy part of the tongue, which closes these openings when 
the animal is breathing, is placed further forward than in the Chelonioidae. The 
lower jaw is thin, and its margin sharp; its front end terminates in a sharp, 
strong, prominent point. 
The size is greater than that of any other family of the order. I have 
seen specimens weighing over a ton. It remains to be ascertained whether this 
family is carnivorous, as the form of the jaws seems to indicate. Though I have 
seen several specimens upon the coasts of Florida, I could learn nothing respect- 
ing their habits. Like the Chelonioidm, they lay a large number of eggs, as I 
infer from the condition of the ovary; but I have never seen mature eggs. 
SECTION III. 
THE FAMILY OF CHELONIOIDJE. 
The family of Chelonioidm was first distinguished by J. E. Gray, and has been 
adopted by all modern herpetologists, though not exactly with the same limits which 
were first assigned to it, since it is now generally made to embrace also the 
Sphargididm.1 But, as we have already seen that the Sphargididae constitute a 
1 With this wider extension, the Chelonioidae of 
modern writers answer exactly to the sub-order of 
Chelonii, Opp., or to the family of Carettoides of Fit- 
zinger, (Neue Classif., etc., 1826.) See above, p. 242. 
But, as characterized here, this family is strictly cir- 
cumscribed within the same limits which Gray at 
first assigned to it, (Ann. of Philos., 1825.) It cor- 
responds also exactly to the sub-family Chelonina 
of Canino, (Sagg. An. Vert. 1831,) and to the genus 
Caretta of Merrem, which is identical with the genus 
Chelonia of Wagler, of Dumeril and Bibron, and of 
most modern writers. Chap. II. 
THE CHEL0NI0ID2E. 
325 
distinct family, the limits of the Chelonioidse are again circumscribed, as they 
were at first. 
The form of the Chelonioidae is that of a heart flattened on one side, from 
the broad end of which projects a large head upon a thick neck, and from the 
widening side of which protrude, in front, a pair of large, flat, wing-like, scaly 
flappers, and below the narrow part of which hang another pair of broad, short, 
scaly rudders. As illustrations of the prominent features of this family, see sev- 
eral attitudes of the Loggerhead Turtle in Pl. 6. 
The body is not, as in Sphargididae, broadest about the arch of the second pair 
of ribs, where the carapace and plastron first meet to encircle it, but continues 
to widen from the front end to about midway, and thence narrows to a point 
behind; while the vertebral column descends constantly and gently along the whole 
thoracic, abdominal, and pelvic regions to the tail. The carapace is a roof 
slanting down on either side from the vertebral column, and thus it continues over 
the pelvis as well as along the thoracic and abdominal regions, and terminates 
behind the sacrum, by the meeting at a point of the outer edges and the middle 
line; the only deviation of its outline in passing from the abdominal to the pel- 
vic region being a slight elevation of the lower edge above the hind legs. The 
carapace is bordered all round by a distinct marginal rim; about the front end 
this rim is turned downwards, but shortly behind the beginning of the union with 
the plastron it flares outward, and so continues to the hind end. In consequence 
of this peculiar form of the marginal rim, the shoulders are much more protected 
than in the Sphargididae; its width adds still more to the protection of the hind 
limbs. The plastron is joined to the carapace from near the arch of the second to 
between the arches of the sixth and seventh pairs of ribs. The plastron and the 
carapace meet at a sharp angle, the plastron descending but little below the level 
of the outer edges. The plastron, like the carapace, grows broad to about midway 
of the body, and narrows thence backward; it underlies a very large part of the 
lower surface. The opening about its hind end, for the protrusion of the limbs 
and tail, is smaller and more under the body than in the Sphargididae. Thus the 
shield, - instead of having, as in Sphargididae, a conical form wrapped closely around 
the thorax and abdomen, and growing narrow backward in passing over those 
regions, then narrowing still much faster to pass over the pelvis, - presents here an 
extended roof-like carapace, with the outer edge sharply defined, flattened upon the 
sides, broadest about midway, protecting above the whole body from one end to 
the other, and a plastron which descends but little below the outer edges. 
The shield, having a form widely different from that of the Shargididae, needs 
also a different structure and different means of support. Instead of a con- 
tinuous layer of fibrous corium protected above by a thin bony sheet, we have 326 
AMERICAN TESTUDINATA. 
Part II. 
here both carapace and plastron composed chiefly of bony plates resting immediately 
upon, and firmly fixed to the true skeleton, and united to one another. The only 
part of the carapace which remains unossified up to adult age is a narrow strip 
along the ribs near their lower ends, just above the ossified marginal rim, and 
extending all round except at each end, where a bony plate is interposed. All 
the ribs, except the first and tenth, reach down to the marginal rim. The eight 
other ribs have each a bony plate extending from the inner end outward ; but 
these bony plates do not reach the bony marginal rim, or if at all, not till late in 
life. The first rib rests on the same plate with the second, and so also the tenth 
with the ninth. Between the inner ends of each pair of costal plates, above the 
vertebral column, and firmly fixed to it, there is a small plate filling the whole 
space; the number of these plates varies somewhat, as one or more of the hinder 
ones is often divided. In front, an odd plate extends from the foremost plate of 
the vertebral row, and from between the foremost pair of costals to the front end 
of the carapace, thus entering into the marginal rim, and connecting it with the 
bony derm above. This plate does not touch immediately any rib or vertebra, but 
is connected with the isolated true bone situated above the lower neck vertebrae, 
and the connection is so intimate that they can hardly be distinguished apart. 
The ninth pair of ribs reaches almost directly backward, passing over the iliac bones, 
and giving support to the narrow, pointed hind end of the body. Wedged between 
the plates which are fixed to these ribs, and behind the last of the plates which 
are fixed to the vertebrae, there is one lying over the sacrum, but free from it; 
sutured to this there is another behind, and sutured to the latter still another, 
which last enters into the marginal rim and terminates it behind. The plates of 
the marginal rim are in one continuous row all round, consisting generally of 
eleven pairs1 besides the odd one at each end; two of these pairs are in advance 
of the first costals. The costal plates are firmly fixed to the ribs and sutured to 
one another, and those of the vertebral row are firmly united to one another and 
to the costals, and those which are fixed to the vertebra? are firmly soldered to 
them; the marginal plates, passing along the ends of the ribs, connect them with 
one another, and they are themselves connected with the bony derm above by 
the odd plates at the ends of the carapace. Thus we have a combination of 
bony derm with the vertebra? and ribs which is well adapted to give strength 
and stability to the broad, roof-like carapace. 
The plastron is connected with the carapace at the lower edge of the mar- 
ginal rim by unossified corium, and is somewhat movable or rather yielding there, 
as it also is along its middle line for the greater part of its length. In Sphar- 
1 The scales which cover these plates arc not so constant. Chap. II. 
the chelonioidse. 
327 
gididse, the plastron narrows continually backward from where it is first joined to 
the carapace; it is firmly wedged in between the curved edges of the carapace, 
and consists of a thick, stiff sheet of unossified fibrous corium, and strengthened 
only by a ring of bones of the true skeleton. In Chelonioidm, however, as the 
plastron spreads out broader at the middle, as it meets the carapace at a sharp 
angle, as it is connected with it by flexible corium, and as it is somewhat flexible 
within itself, it also needs a different structure. It is made up partly of unossified 
corium, and partly of plates composed of true bone and of bony derm. These plates 
form by far the larger part of the whole, and sometimes nearly the whole plastron. 
The two kinds of bone are so united as to be hardly distinguishable ; we shall 
therefore speak of the plates without reference to their composition. There are nine 
of them, four pairs and one odd one. The first pair is situated between the front 
limbs; they meet in front and spread apart backward, and overlap the outside of 
the front edges of the next pair, which are here turned forward; at their ends, 
where they meet, they are broad and strong, but grow slender backward. Joined 
to the hind edges of this pair, and reaching back somewhat between the inner 
edges of the second pair, is the odd plate; it is interposed against the front pair 
at their union, and prevents the formation of a hinge in that end of the plastron. 
These three plates, thus united, make a broad, firm support for the shoulder appa- 
ratus. The second and third pairs reach across from one edge of the carapace 
to the other. These two pairs are sutured to one another, and together they 
make up much the largest part of the plastron; their outer edges are connected 
with the marginal rim by unossified corium, and their inner edges with one 
another in the same way, but they approach the marginal rim and one another 
by spine-like processes reaching out from near the fore end of the second and 
the hind end of the third pair. The fourth pair underlie the pelvis and meet 
behind it; they are long and slender, extending more backward than inward, and 
are joined, before, to the third pair. 
In this family, then, the dermal shield is much more extended and more bony 
than in the Sphargididae; the wings and paddles are more covered by the shield 
and less free, and the body is more flattened upon the sides and below. These 
characters seem to indicate that the animal is less capable of powerful and long- 
continued flight. 
The shield is everywhere covered with epidermal scales. These scales are 
largest upon the carapace, where there is one median row along the vertebral 
column, and one on each side above the costal plates, besides the row which 
protects the marginal rim; the foremost of these is an odd, short, but very broad 
scale; the hindmost, on the contrary, form one pair. Upon the plastron there is a 
double row of larger scales in the middle, and a row of smaller ones on each side 328 
AMERICAN TESTUDINATA. 
Part II. 
upon its junction with the carapace. On the free skin, the epidermis is also formed 
into a kind of scales; but upon the wings and paddles the scales become stiff and 
hard, and they are larger along their inner and outer edges, as they are also where 
the skin fits close to the bones of the head. The scales on the inner edge of 
the paddles recall the large feathers of the wings of birds by their arrangement 
and their elongated form. The central scale upon the skull is the largest. The 
horny sheath of the bill is very strong. 
As in Sphargididae, the jugal, parietal, postfrontal, temporal, and mastoid bones 
of the Chelonioidae unite to make a bony covering over the whole head back of the 
eyes, protecting the temporal muscles and the brain-box, and projecting even back 
over the first neck vertebrae; but here the parietal bones are not so exclusively 
devoted to this office as in the Sphargididae, for they reach down to the floor of 
the skull, and add to the length of the brain-box in front. The temporal bones do 
not, as in the Sphargididae, add to the width of the head, but reach directly forward 
and so bring the bony arch further down over the attachment of the temporal mus- 
cles to the lower jaw. The prefrontals meet before the frontals, and so carry the 
top of the skull further over the nasal region. The alveolar margin of the upper 
jaw has not the deep depressions or the sharp, tooth-like projections observed in 
Shargididm. The horizontal alveolar surface is very broad all round the upper 
jaw, and the palatines project inward from the suture with the maxillaries, unit- 
ing, together with the end of the vomer and the alveolar surface, to make a 
very broad roof below the palate proper. The passages from the nasal cavity 
necessarily descend very obliquely over this roof, to open into the mouth behind 
it. The lower jaw is very thick, especially at the symphysis, and its alveolar sur- 
face is broad. The neck moves somewhat up and down upon the first dorsal ver- 
tebra, and the head may be drawn back so as to reach the carapace, but it can- 
not be withdrawn under it. 
The size of the members of this family is very great, much greater than the 
average size of the Amydae, though they do not grow so large as the Sphar- 
gididae. The food of most of them is known to consist of aquatic plants, sea- 
weeds, and the like. Like all the herbivorous animals, the Chelonioidae are shy 
and inoffensive; they do not bite, even when hard pressed, but strike with their 
powerful flappers, and try to make their escape by increased speed. The North 
American Chelonioidae lay their eggs towards the end of May or in the beginning 
of June. They lay a large number of them, about one hundred at a time, and 
even more, which they deposit on shore, in the dry sand. These eggs are not 
very large in comparison to the size of the animal, and not perfectly spherical, 
their orbicular outline being more or less irregular. I have no reason to trust 
the reports that they lay eggs more than once in a year. Chap. II. 
329 
THE TRIONYCHIDJE. 
SECTION IV. 
THE FAMILY OF TRIONYCHIDJE. 
This family was first distinguished by J. E. Gray, and afterwards adopted by 
Bell, Fitzinger, Wiegman, Canino, and Dumeril and Bibron, while Wagler unites it 
with the other fresh-water Turtles.1 
The form of the Trionychidm resembles a flat orbicular disc, slightly elongated, 
with a long, pointed head projecting upon a long, slender neck, and two pairs of 
limbs, one before and the other behind, with broad, webbed feet moving hori- 
zontally. 
The body is low, flattened, and spread out wide. The upper surface nowhere 
arches high above the outer edge, either crosswise or lengthwise. The middle line 
above, along the dorsal vertebral column, or rather the cord of its slightly curved 
arc, is very nearly parallel to the flat lower surface upon which the body rests. 
From this middle line the upper surface descends slowly on either side toward the 
outer edge, lowest about the shoulders in the arch of the third pair of ribs, less 
and less backward, until over the pelvic region the arch is very slight. As this 
line is parallel to the base upon which the body rests, the outer edge of the 
shield rises as the upper surface flattens, that is, from the shoulders backward. At 
the shoulders it is but little above the flattened part of the lower surface, so that 
there the bulk of the body is above the plastron and within the arch of the cara- 
pace, while at the hind end it is below the carapace and within the inverted arch 
of the plastron. The opening in the shield for the protrusion of the limbs and 
tail about the hind end is as high or higher than that about the front end 
for the protrusion of the head and front limbs. The body is bluntly curved 
about the front end; it is much broader across the shoulders than across the pel- 
vis, and more pointed behind than before, but the projection of the marginal rim 
beyond the body gives very different proportions to the carapace. This rim pro- 
1 This family corresponds exactly to the genus 
Trionyx of Geoffroy, from which its present name is 
derived. Gray writes the family name Trionicidte, 
(Ann. Phil. 1825,) and Trionycidas, (Cat. Brit. Mus. 
1844;) as also does Canino, (Saggio An. Vert. 1831.) 
Bell writes it Trionichidas, (Zool. Jour. 1828.) Fit- 
zinger has it Trionychoidea, (Neue Classif. 1826.) 
Wiegmann changed the name to Chilotm, (Handb. 
Zool. 1832.) Dumeril and Bibron introduced a third 
name for this same family, calling it Potamides, 
(Erpet. gener. 1835.) The name borrowed from the 
genus Trionyx, having the priority over those of 
Dumeril and Bibron, and of Wiegmann, must be 
retained ; but it must be spelled Trionychid^e. 330 
AMERICAN TESTUDINATA. 
Part II. 
jects very little, if at all, immediately about the front end; but, beginning at the 
arch of the third pair of ribs, where the carapace and plastron first meet, it grows 
wider and wider backward, until about the hind end it becomes a broad leaf, 
which, when the animal is at rest, in the American species at least, drops down 
behind the body on account of its own weight. 
The carapace and plastron first meet in the arch of the third pair of ribs, 
there encircling the shoulders, and continue to encircle the body from thence to 
between the arches of the fifth and sixth pairs. The plastron, like the carapace, 
reaches in front to the end of the body, and no further; after separating from the 
carapace it extends back under the pelvis, and in Trionyx proper1 underlies the 
hind legs, but is there unossified. At the front end, in the American species at 
least, the shield is flexible above and below, and under the control of muscles. 
The two margins may even be brought together so as to close entirely the front 
end of the body, including the head and the greater part of the front limbs. 
The shield is by no means entirely ossified; and, where the ossification exists, it 
is irregular, and less intimately connected with the true skeleton than in the other 
families of the sub-order. In the adult animal, a continuous area of the carapace, 
which overlies the greater part of the viscera of the body, is ossified, and extends 
over the vertebral column, from the neck to the sacrum, and far down on the ribs 
toward their outer end. This bony derm is divided into plates, which correspond 
more or less regularly to the bones of the true skeleton, to which they are fixed. 
The isolated odd plate of true bone is constant, and stretches, with the bony derm, 
across the front end of the shield from one to the other of the second pair of 
ribs, over the last vertebrae of the back and the first of the neck. From this 
plate the vertebral row extends back quite regularly over five or six vertebrae, 
or even to the hind end of the carapace, but sometimes several of the hinder 
ones are divided, and sometimes one, two, or three of them are wanting, so that 
the last two or three pairs of costals meet at their inner ends. The eight pairs 
of costal plates are pretty constant, but the last pair is not always entirely or 
even at all separated from the one next before it. All around and outside of 
this region of bony derm, the carapace is either entirely unossified or has only 
a narrow border of bony derm at the ends. So the marginal rim cannot be 
accurately distinguished from the carapace proper, at least not by sutured plates. 
The plastron is fixed on either side to the leathery border of the carapace. Its 
framework of true bones consists of four pairs and an odd bone. Two pairs, the 
second and third, reach from the carapace inward, but do not meet, or if at all, not 
1 Trionyx, in contradistinction to Aspidonectes, 
corresponds to the genus Cryptopus of Dumeril and 
Bibron, (Erpet. gener., 1835,) or to Emyda of J. 
E. Gray, (Cat. Brit. Mus., 1844.) Chap. II. 
THE TRIONYCHIML 
331 
till late in life. The fourth pair extend backward under the pelvis; their front 
edges extend pretty directly inward, their hind edges more backward, so that they 
are broad where they meet under the pelvis. The odd bone is long and slender, 
and arches forward and overlaps the second pair. The bones of the first pair are 
small, and bent nearly to a right angle; one of their limbs rests against the odd 
bone, while the other reaches almost directly forward. A thick derm underlies all 
this bony framework, and spreads out before it, under the shoulders, as far as the 
end of the body, and, in Trionyx proper, behind it, under the hind legs. A con- 
siderable portion of this derm, on and immediately around the bony frame, is ossi- 
fied; but the larger part, including a space in the middle, is not. There is, on that 
account, some mobility in the plastron, so that when the animal takes breath it 
yields and expands. The microscopic structure of the unossified derm has already 
been illustrated above.1 
As stated before, the ossification of the shield is very irregular, as it undergoes a 
great variety of changes during its growth. There is, however, a regular alternation 
between its growth and that of the true skeleton, with which it is connected, now 
the one advancing,2 now the other. The ossification is much less fixed and deter- 
mined, both as to extent and position, than in the other families of the sub-order. 
These peculiarities, and their relation to the general form, are still subjects of inves- 
tigation, and consequently their value as family characters is not fully determined. 
This much however is certain, that the ossification goes on more slowly, is not 
carried so far, is much less intimately connected with the true skeleton, and is 
more varying, than in the other families of the sub-order. 
As shown above, the vertebral column is nearly at the same level in the sacral 
region as within the scapular arch. The pelvis and shoulder apparatus have nearly 
the same height; they take the proportions of a cross section of the body, that 
is, they are low and wide spread. The scapula is long, as also are the coracoid 
and the acromion; but the scapula reaches far outward, and the acromion from 
thence inward, so that the arch is stretched out, as it were, sidewise, and the 
shoulder joints are carried close to the edges of the body. The sacrum is broad, 
the iliac bones are nearly parallel, and the pelvis is as broad across the hip joints 
1 See Chap. 1, Sect. 5, p. 263. 
2 The regular alternation which is observed in 
the increase and enlargement of the bony derm and 
of the true skeleton, especially at the ends of the 
ribs, is an additional proof that the shield is not to 
be considered as formed by a dilatation of the ribs 
only, but chiefly by the ossification of the derm. The 
differences noticed by Owen, in his paper on the fossil 
Trionyx, (Transact. Pakeont. Society, 1849,) as far 
as they relate to the extension of the ribs beyond 
the solid carapace and to the form of its rim, are 
not specific, but may be observed in a series of speci- 
mens of the same species, in different stages of ossi- 
fication. I have satisfied myself of this by a careful 
comparison of fourteen skeletons of Aspidonectes 
spinifer, and muticus, of all ages. 332 
AMERICAN TESTUDINATA. 
Part II. 
as across the sacrum. The ischium is small, the pubis broad and flat; neither 
extends downward to any considerable distance from the hip joints. The feet are 
very large, and longer than that part of the legs which extends between the knees 
and elbows, and the joints of the wrist and the ankle. The toes are long, united 
by a web, and capable of being widely spread ; the inner one is the stoutest, 
and from thence outward the others are more and more slender, so that the 
last two, and especially the last one, can serve for little else than to stretch the 
web; the middle one is the longest, and on either side of it the others grow 
shorter; the first, second, and third, in the genera examined,1 have strong nails, 
the others none. The inner side of the feet and legs is thick, but from the 
outer side a broad web reaches out and adds much to the surface presented to 
the resistance of the water in swimming. The skin is not very closely attached 
to the legs, and hardly surrounds the front ones at all above the elbows. 
The neck is very long and flexible. The head too is long, and terminated by 
a long, leathery snout. The brain-box forms a marked angle with the front part 
of the head, which is distinctly bent downward. The upper surface of the skull, 
after passing over the brain, turns steeply downward ; the lower surface rises 
from its hind end to the front end of the brain-box, and falls thence forward, 
but not as steeply as the upper surface. The lower jaw grows more flattened 
toward the front end. The sides of the front part of the head approach each 
other forward, as in all the other representatives of the order. So the whole 
front part of the head, including the lower jaw, tapers to the projecting leathery 
snout. The mastoids are long, conical, narrow, from the brain-box outward, and 
taper backward to a point. The opening to the ear cavity is elongated length- 
wise of the brain-box. The temporal arch is narrow, flat, and thin, and not far 
removed from the brain-box, so that the passage within it for the temporal muscle 
is small. The arch, from the top of the skull down to the maxillary, is also 
narrow, and brought near the brain-box. The parietals project very little or 
not at all outward. Thus the temporal muscle has a slight, narrow, bony cov- 
ering. The pterygoids are broad, and have but slight depressions on their outer 
edges. The sphenoid reaches forward between the pterygoids to the palatines. The 
openings in the palate, by which the mouth communicates obliquely with the 
nasal cavity, are large, and extend far back ; the corresponding openings in the 
back wall of the nasal cavity are also large, and the foramen olfactorium is large. 
There is in the skull an opening also in front of the vomer, just within and 
behind the curved end of the alveolar surface; but, in life, this opening is filled 
with a fleshy cushion. 
1 These details are truly family characters, as they determine the form of the feet. Chap. II. 
THE TRI0NYCHID2E. 
333 
The free skin is loose about the neck and limbs. There are no epidermal 
scales, excepting a few narrow, long ones on the limbs, which serve not so much 
for protection as to stiffen the web. 
The principal habitat of the members of this family is the muddy bottom of 
shallow waters. They bury themselves in the soft mud, leaving only the head, 
or a small part of it, exposed. They take breath from time to time, without 
moving the body, by raising up the long neck and head and carrying the leath- 
ery snout above water. They sometimes stay under water a long time, without 
taking breath; in one instance, a specimen has been seen to remain under water for 
more than half an hour without raising its snout above the surface. The nature 
of the habitat is clearly connected with some of the prominent family character- 
istics. For instance, the buried body needs not the protection of the fully ossified 
shield which the other families have : the long neck and head, the projecting snout, 
and the free communication between the nasal openings and the mouth are all con- 
nected with the manner of taking breath. These animals rarely go on dry land, 
and when they do, their locomotion is laborious and constrained; yet it is iden- 
tical with that of the other Amydae in the alternation of the limbs of the two 
sides of the body. When moving through the water, they strike horizontally with 
both pairs of limbs,1 alternating however between the right and left foot of each 
pair ; but when they start suddenly, the front limbs are seen moving together 
towards the tip of the snout, and then striking simultaneously backward with great 
power to propel the body forward. As the shoulders are placed so near the edge 
of the body, and the shield does not project free about the front end, the front 
limbs move mostly beyond the shield, in front and at the sides ; and as the 
outer edge is sharp, and the feet are broad, their web reaches above as well as 
below the plane of that edge, and when they strike, they drive the water back, 
partly over and partly under it. The hind legs move back and forth below the 
carapace and drive the water backward without hinderance, for the flexible broad 
rim is so light in the water that it yields readily to the current. When these 
animals move along on the bottom, the limbs still move horizontally, the web 
striking against the water, and the inner toes against the bottom. They also bur- 
row horizontally, going under the mud only to the depth of a thin layer. When 
burrowing, they carry the hind feet forward and outward, and thus bracing them- 
selves, press the body forward, digging a part of the mud with the fore feet, 
and raising a part of it up on the body ; the mud is loosened by the strong 
1 All the figures which I know, representing 
members of this family, are very incorrect. The 
feet are never brought down, as in other Amydae, 
below the level of the lower surface of the body, 
as they are represented in all the figures of Tri- 
onychidae thus far published. 334 
AMERICAN TESTUDINATA. 
Part II. 
inner toes, but the whole foot aids in removing it. In walking on dry land, the 
legs move as nearly horizontally in propelling the body forward as is consistent 
with the resistance offered by the ground. The animal readily resorts to the shield 
for protection. The neck and head are withdrawn entirely within the shield, the 
skin rolling off from the greater part of the neck, and allowing it to protrude 
naked among the viscera. The legs are withdrawn horizontally, and the skin slips 
off so far that it does not surround them, except below the knees and elbows. 
When thus withdrawn, the humerus is carried round into or before the wide spread 
scapular arch, the elbow being placed very near the head or neck; the fore leg 
and foot are turned back upon the humerus, the flat surface of the foot being 
nearly horizontal, so that its outer edge rests against the humerus. The knee is 
carried almost directly forward, the fore leg turned backward against the femur, 
and the foot again turned somewhat forward, its flat surface being nearly hori- 
zontal. See Pl. 6. 
It is easy to perceive the close relations which exist, in this family, between 
the mode of locomotion, the movements and position of the limbs, and the general 
form of the body. The limbs, for example, move and are withdrawn horizontally ; 
so also is the body widely stretched out horizontally, and moreover it is flat and 
low. The flat front end offers little resistance to the water before it; its sharp 
outer edge offers as little resistance also to the water which is driven back by 
the fore feet. Again, this low end is well adapted to entering the mud, and the 
fore feet to loosen and remove as much of it as is necessary to enable them to 
bury themselves in the soft ground. The flattening of the carapace backward is 
necessary to allow free horizontal movement to the hind legs. 
The habits of the Trionychidae are little known. In confinement, they exhibit 
great quickness in their motions, which are abrupt and unsteady, except when 
they swim rapidly in one direction. They then dart their long, slender neck 
quickly forward or sideways and upwards, as the Snakes do, and bite in the same 
way, striking suddenly the objects they aim at. Different attitudes of the North 
American species are represented in Pl. 6. They feed upon shells, especially upon 
Anodontas and Paludinas, fragments of which 1 have frequently found among their 
faeces and in their intestine. They probably grope for them in the mud with 
their proboscis. They lay from twelve to twenty and more eggs, of a spherical 
form, and about the size of a musket ball, which they deposit on shore in the 
sand near the water's edge. The shell of these eggs is thick but very brittle. 
The eggs of the Trionychidaa and those of the Cinosternoidae are the only 
Turtles' eggs I know, the shell of which is not more or less flexible. 335 
Chap. II. 
THE CHELYOHLE. 
SECTION V. 
FAMILY OF CHELYOID2E. 
The family of Chelyoidae, as characterized below, embraces only one genus, the 
Chelys of South America. As limited by former observers, the type of Pleuro- 
deres, to which Chelys belongs, combines features which are parallel to those that 
characterize the families of Trionychidm, Chelydroidae, Cinosternoidse, and Emydoidae. 
These peculiarities would seem to be remarkably blended here, if this type were 
to constitute a single family. I believe, however, that this is not the case.1 I 
have, at least, satisfied myself already, that the Chelyoidm are very different from 
the other Pleuroderes, as the following description may show. 
The dorsal part of the vertebral column, from the first dorsal vertebra back- 
1 Of all the types of Testudinata, that of Chely- 
dina is the only one, for the examination of which I 
have not been able to secure ample materials. Hav- 
ing however myself, when student in the Univer- 
sity of Munich, made most of the skeletons which 
are figured in the Atlas to Wagler's Natiir. System 
Amphibien, 1830, I have derived sufficient informa- 
tion from his illustrations of this subject to satisfy 
myself that several families are still included under 
the group called Elodites Pleuroderes, by Dumeril 
and Bibron, (Erpet. gener., 1835.) The first allusion 
to the propriety of considering them as a distinct 
group may be found in J. E. Gray's Synopsis of the 
Genera of Reptiles, (Ann. of Philos., 1825,) where 
they are enumerated as a sub-family of the Emy- 
doidae, under the name of Chelidina. Soon after- 
wards Fitzinger considered them as a distinct family, 
under the name of Chelydoidea, (Neue Classif., 1826.) 
This family was afterwards adopted by Wiegmann, 
under the name Chelydae, (Handb. d. Zool., 1832,) 
then subdivided into two sub-families by Canino, 
under the names of Hydraspidina and Chelina, (Che- 
loniorum, Tab. Anal., 1836.) These two divisions 
are considered as families by Fitzinger, in his latest 
work, (Syst. Amph., 1843,) under the names of Hy- 
draspides and Chelydae. Gray, however, considers 
them still as one family, under the name of Chelididae, 
(Cat Brit. Mas., 1844.) I hold that the separation 
of the Chelyoidae from the Hydraspides, as a distinct 
family, is founded in nature. From the examination 
of several specimens in the Museum of the Essex 
Institute in Salem, I have satisfied myself that the 
genus Chelys of Dumeril truly constitutes of itself a 
natural family. But I am by no means convinced 
that the genera referred to the family of Hydraspides 
are so closely allied to one another as to form one nat- 
ural family. There are those among them which re- 
call the Cinosternoids, while others resemble more the 
Emydoids. I am, therefore, inclined to believe, though 
I have not the means to show, that as Chelys consti- 
tutes a natural family among the Pleuroderes, analo- 
gous to the Chelydroidae among the Cryptoderes, so 
does Sternothaerus correspond to the Cinosternoids, 
while the other genera correspond to the bulk of the 
Emydoids, thus forming two natural families, which 
may be called Sternothaeroidae and Hydraspides. It 
may be, however, that several of the genera of the 
Hydraspides differ still more from the others than the 
sub-families of Emydoidte among themselves, as, for 
instance, Podocnemis and Chelodina. This type of 
Pleuroderes requires yet to be thoroughly studied, in 
all its ramifications, and minutely compared with the 
corresponding types of Cryptoderes, characterized in 
the following pages as distinct families. 336 
AMERICAN TESTUDINATA. 
Part II. 
ward, is straight, and parallel to the flattened part of the lower surface. The spinous 
apophyses of the back are very long; longest about midway of the body, a little 
shorter toward the neck, and shortest at the meeting with the sacrum. Thus 
the median longitudinal line of the upper surface is high above the column; it 
arches from end to end, descending much lower behind than before; it reaches 
far forward over the neck.1 The upper surflice is broad, bluntly curved at the 
front end, and narrower and more pointed behind; it reaches far forward in 
front of the arch of the first and second pairs of ribs, but arches little from side 
to side, and the bulk of the body is below the outer edge; it is depressed on 
either side of the middle longitudinal line, along where the ribs first meet it in 
passing out from the vertebras. The outer edge is high above the base upon 
which the body rests; it falls from the front end to about midway, then rises 
over the hind legs, and again falls behind the pelvis, where it is lowest. The 
flattened lower surface is long and rather broad; it reaches forward somewhat 
farther than the upper surface, and backward to the hind edge of the pelvis; 
it is broadest nearly under the third pair of ribs, where it has about half the 
width of the body; it narrows but little forward, having a blunt, broad front 
end, but backward it narrows faster, and at its hind end has about the same 
width as the pelvis ; it rises somewhat from the region where it is broadest to 
the front end. 
It is important to notice, that both the upper and the lower surface extend 
far in front of the first vertebra of the back, and thus a large part (more than 
a third) of the neck is inclosed within the walls of the body. The carapace 
and plastron are joined from the arch of the second to that of the fifth pair 
of ribs. The bridge on each side, reaching down from the outer edge to the 
flattened lower surface, is necessarily long, and the openings about the ends of 
the body for the protrusion of the head and limbs and tail are high and large. 
The bridges reach considerably inward in descending; their free edges are turned 
far into the body, and the upper edge is united by long sutures with the 
second and fifth ribs. The plastron underlies the whole broad flattened lower 
surface of the body; its free edges project little beyond their attachment, in fact 
not at all, except about the front end, so that the plastron does not protect, as 
is the case in the Emydoidse, any extensive part of the lower surface beyond that 
to which it is actually attached. The free edges of the carapace project rather 
widely over the legs, but little behind the pelvis, and only slightly over the neck. 
1 The effects produced in the outline of the 
outer surface by the varying thickness of the derm 
are omitted here, and noted below in the descrip- 
tion of the shield, as they do not constitute an essen- 
tial element of the form, but are rather an incidental 
structural result of it. 337 
Chap. II. 
THE CHELYOIDJE. 
The curve from side to side of the outer surface of the carapace is interrupted 
by three ridges, formed by the increased thickness of the derm, besides the 
depressions spoken of above, which enter into the form of the body itself. The 
middle ridge passes along over the vertebral column; it is slight at the front 
end of the shield, broadest above the first two or three dorsal vertebrae, higher 
and narrower backward above the sacrum, and then decreases to the hind end 
of the shield; it occupies the space between the depressions already mentioned. 
The other ridges are smaller, and situated just outside of these depressions. 
The shield is thick, completely ossified, and regularly divided into plates. Be- 
sides the eleven pairs of marginal plates and the eight pairs of costals, the usual 
plates of the vertebral row, with the odd plates at each end terminating the mar- 
ginal rim, are constant in the carapace. The odd plate and the other marginal 
plates in front, as well as the first pair of costals, are very large, and give the 
unusual length and breadth to the carapace in front of the first costal arch. 
The plastron is made up of nine plates, as usually, four pairs and one odd 
one. The second and third pairs reach entirely across, unite with the carapace 
on each side, and form the bridges and the greater part of the flattened por- 
tion of the plastron. The first pair meet in front, and are united by a bony 
suture, and, reaching backward more than outward, are joined to the second pair 
by sutures of about the same length. These and the odd plate are large, and 
give the unusual size to the front part of the plastron. The fourth pair is the 
smallest, and just underlies the pelvis. 
The scapular arch, dowm to the shoulder joints, is nearly perpendicular. The 
iliac bones are nearly perpendicular and parallel; their upper ends are very 
large, and are firmly sutured to the shield above. The ischium too is sutured 
to the shield below, as also is the pubis. Thus the pelvis is firmly fixed to the 
shield above and below. This support, together with that of the strong bridges, 
the thickness of the bony derm generally, and the additional ridges of the cara- 
pace, make the shield very firm, in spite of the rather slight curvature of the 
carapace from side to side. 
The ribs extend far out from the vertebras before meeting the shield, and 
the space above them on either side of the spinous apophyses is wide as well 
as high, and affords place for the passage and attachment of very large muscles. 
The first dorsal vertebra is turned down at the front end, and its body is 
much enlarged, so as to present a large, round, articulating surface. Its articulating 
processes, instead of reaching as usually outward and downward, are placed higher 
up, near together, and make, with the body of the vertebra, a long, perpendic- 
ular axis, upon which the adjoining neck vertebra swings freely from side to side, 
and but little up and down. This is the prevailing direction of the axis through 338 
AMERICAN TESTUDINATA. 
Part II. 
the neck; but approaching the head there is more freedom of movement up and 
down, and the head itself turns freely in both planes on the nearest two joints. 
So the general direction of the bending of the neck is sidewise, and when the 
animal resorts to the shield for protection, it turns the head to one side,1 and 
does not carry it directly back, bending the neck under the dorsal column, as 
is the usual way. The unusual length of the dorsal spinous apophyses, and the 
long extension of the bony walls of the body in front of the dorsal column and 
of the first costal arch, clearly depend upon the habit of these Turtles of bending 
the neck sidewise. The arch of the atlas is firmly fixed to its body; it is also 
firmly fixed to the body of the epistropheus, and closes over it, so that this one 
arch with two vertebral bodies acts fully as one vertebra, which articulates as such 
with the occipital condyle, and the vertebra next behind. 
The head is broad across the ears, low at the hind end of the brain-box, 
and almost fiat in front of it. The middle of the floor of the skull, from the 
occipital condyle to the alveolar surface, is almost straight. The walls of the 
ear cavities, as they open from the brain-box, reach far forward and downward, 
and a line across the middle of the outer ends of these cavities would pass nearly 
over the middle of the brain-box. The brain-box is very low; the lateral 
occipitals meet over it, and the occipital crest raises the parietals up some dis- 
tance, but they fall fast forward, and at their front ends the roof and floor of 
the skull are brought together, leaving the passage from the brain cavity forward, 
and the open space on each side, very small and low; the roof is raised a little 
in passing forward over the cavities of the eyes and of the nose. The eyes are 
placed far forward, and look upward as well as outward. The jugals and postfron- 
tals are broad behind the eyes, and lie for the most part immediately upon the 
pterygoids and palatines. There is no arch from the ear region forward, but 
instead there is one over the temporal muscles, formed by the meeting of the 
mastoids and parietals. The front wall of the ear cavity curves sharply forward. 
There is a deep, large depression in the mastoid behind the os tympani for the 
passage and attachment of the digastric muscle. The roof of the mouth is very 
broad: the pterygoids have no depression in their outer edges; they turn down 
on the os tympani, reaching as low as the articulating surface, so that there the 
roof of the mouth is a flattened arch, but at the front end it is curved up 
toward the outer edges. 
The upper alveolar surface is merely a slight depression in the thickness of 
the jaw. The floor of the nasal cavity projects forward beyond that surface. 
1 All the fresh-water Turtles which have this 
structure of the neck have been united by Dumeril 
and Bibron into one group, under the name of Pleu- 
roderes, as a sub-family of the Elodites. Chap. II. 
THE CHELY0ID2E. 
339 
In the fresh state, this cavity is prolonged by a membranous snout, as in Trionyx. 
The lower jaw is thin, excepting at the condyles, where it is thickened on the inner 
side to a nearly spherical form; the articulating ball projects somewhat higher than 
the upper edge, but it is lower than the lower edge of the jaw just before it; 
it rolls by a broad and long convex surface on the articulating surface above. 
The jaw rises forward to the coronal angle, where it is so high and broad that 
its upper edge rises above the top of that part of the skull which it incloses; 
from the angle forward it is small and blunt, and fits closely into the alveolar 
depression above. The tongue bones are largely developed, and make a broad, 
firm floor under the cavity of the mouth. 
Most of the many peculiarities of the head are clearly connected with the 
form of the mouth, and thus with the kind of food, and manner of catching 
and devouring it. The jaws are weak, and neither pointed nor sharp-edged; and 
therefore unfit for catching large, active prey, or tearing any tough vegetable or 
animal matter. The mouth is broad but very close, when its roof and floor are 
brought near together; it seems on that account best fitted for catching and 
swallowing minute animals. The mode of articulating of the lower jaw, and the 
large size of the depression in the mastoids for the digastric muscle, indicate 
perhaps that the jaws are opened and shut quickly and continuously with a 
movement somewhat like that of a duck's bill. The legs are strong, and the 
feet broad and compact, with long, sharp claws. 
This family contains a single genus, well known under the name of Chelys. It 
embraces only a single species, called Matamata in tropical South America, where it 
is common. Its habits are little known. From the resemblance of this Turtle 
to the Chelydroidse and the Trionychidae, I am inclined, however, to infer that, 
like these, it lays spherical eggs. 
The family first described by Fitzinger under the name of Hydraspides1 was 
soon afterwards united, by J. E. Gray,2 with the Chelyoidse; but I believe this to 
be a mistake,3 if I am permitted to express an opinion after having had so few 
1 Fitzinger, Syst. Rept., 1843, 8vo. 
2 J. E. Gray, Cat. Brit. Mus., 1844, 8vo. 
3 It has already been remarked in a note, p. 335, 
that the Turtles united as one natural group under 
the names of Chelididte, or Elodites Pleuroderes, do 
not constitute a natural family, but embrace a number 
of families, linked together by the peculiar structure 
of the neck, and besides by the close connection be- 
tween the pelvis and the carapace and plastron. Of 
these families I have only been able to examine the 
Chelyoidae proper with sufficient precision to ascer- 
tain fully their family characters. I take, however, 
this opportunity to call the attention of herpetologists 
to the differences I have thus far noticed among the 
other groups. I have already stated above, that, as 
the Chelyoidae proper recall the Chelydroidae, the 
Sternothaeroidae form in the same manner the coun- 
terpart of the Cinosternoidae, while Pelomedusa and 
Pentonyx remind us of the true Emydoidae. The Hy- 
draspides, restricted to the genera Platemys, Rhine- 340 
AMERICAN TESTUDINATA. 
Part II. 
opportunities of examining these Turtles. The united Chelyoidae and Hydraspides 
form simply a section of the family of Elodites in the classification of Dumeril and 
inys, Phrynops, and Hydraspis, agree in having no 
temporal arch, while the parietals are broad, long, 
and Hat, and the parietal arch is very narrow and far 
backward. The type of Hydromedusa and Chelo- 
dina, which may also constitute a distinct family, 
differs from the genuine Hydraspides in its parietals, 
that are gradually narrowing backward to form a 
ridge with the upper occipital, carrying the parietal 
arch even further backward than in the Hydraspides ; 
as in these, the temporal arch is also wanting. The 
Podocnemides present still more striking peculiarities. 
As in the marine Chelonioidue, the parietal and tem- 
poral arches are united to form a broad roof over the 
temporal region. This is the only group of Testudi- 
nata in which the peculiarities of the skull of Che- 
lonii and Amydae are intimately combined. On this 
account, I expect that the Podocnemides will be found 
to agree much more closely, in those structural pecu- 
liarities which constitute family characters, with the 
earlier representatives of this order in past geological 
ages, than with any other type. It is deeply to 
be regretted, therefore, that the beautiful series of 
fossil Turtles found by Hugi in the jurassic limestone 
of Solothurn, in Switzerland, have not yet been 
examined and described with that minuteness which 
would furnish the means of a direct comparison with 
the living types ; for they exhibit, more distinctly than 
any other fossil Turtles I have seen, a surprising 
combination of Chelonioid and Amydoid characters. 
This is also the case with the genera Eurysternum, 
Munst., and Idiochelys, Myr., described by Herm, 
von Meyer, in Munster's Beitrage, 1839. 
It ought also to be noticed in this connection, 
that the oldest fossil species, referred to the family of 
Chelonioidaa by Owen in his beautiful illustrations of 
the British Reptiles, (Trans. Palasont. Soc., 1851,) 
differ in many respects from the marine Turtles, and 
present, especially in their oval form, which is quite 
distinct from that of the living Chelonioidm, features 
which are characteristic of the living Emydoidae, or, 
rather, common to all the Testudinata of the present 
period, in the younger stages of their development. 
By its rounded form and small size, the Chelonia of 
Glaris differs also greatly from the living Chelonioidae. 
It certainly constitutes a distinct genus, characterized 
by the peculiar proportions in the length of the fingers 
of the front paddles. A knowledge of these combi- 
nations of characters, in the earlier representatives of 
the order, is of great importance with reference to 
the question of their succession in former geological 
periods, and that of their relations to the surrounding 
mediums. Most of the oldest fossil Testudinata have 
been referred to fresh-water types, and their occur- 
rence in the oolitic and cretaceous rocks, with other 
fossils evidently belonging to marine types, has led 
to the supposition (see Pictet, Paleont., vol. i., p. 
440) that they may have been floated into the sea 
from the adjoining fresh waters. I hold that such an 
assumption is not necessary. There is no closer re- 
lation between the secondary Testudinata and the 
Jiving representatives of this order than between the 
fossil Ganoids of the jurassic and cretaceous periods 
and the living Sauroids ; and yet it would be entirely 
gratuitous to assume that the jurassic and cretaceous 
oceans were fresh-water basins, because the living 
species of Lepidosteus and Polypterus inhabit the 
rivers of North America and of Africa. Again: the 
occurrence of fresh-water Turtles in the jurassic for- 
mation, at a period during which no Chelonioids are 
known to have existed, would lead to the conclusion 
that there is no relation between the gradation of 
these animals and the order of their succession in 
past times; while it appears, on the contrary, that, far 
from being genuine Emydoids, the earliest Testudi- 
nata exhibit simultaneously synthetic and embry- 
onic features, exactly as we have already observed in 
many other types. (Comp. Part I., Sect. 24, 25, and 
26, p. 107-118.) Now that the families of Testudi- 
nata are better defined and more fully characterized, 
a renewed comparison of the fossil and living repre- 
sentatives of this order would add greatly to our 
knowledge, especially if the investigation was made 
with direct reference to the questions alluded to 
above. The lateral movability of the neck of the Chap. II. 
THE CHELYDROIDJE. 
341 
Bibron, under the name of Elodites Pleuroderes. Wagler was the first to notice 
the characteristic lateral movability of the neck of these Turtles;1 but neither 
he nor any of the earlier herpetologists availed themselves of this remarkable 
anatomical peculiarity to separate the fresh-water Turtles into minor groups. 
SECTION VI. 
FAMILY OF CHELYDROIDjE. 
The family distinguished by Swainson2 under the name of Chelidridae rests upon 
an unnatural combination of the true Chelydroidae and the Chelyoidae, as char- 
acterized in the preceding section. But, while such an association of these Tur- 
tles is contrary to the principles of classification discussed in the first part of this 
work, it seems more in accordance with the practice generally followed in similar 
cases to adopt the name proposed by Swainson than to frame another for the 
family characterized in the following pages. This is the more feasible, as Swain- 
son himself considered the genus Chelydra as the type of the family. All the 
other naturalists who have written upon the Reptiles unite the Chelydroidae with 
the Emydoidae. 
The body of the Chelydroidae is high in front, and low behind; the middle line 
along the fixed part of the vertebral column descends from its front end backwards; 
Pleuroderes, in particular, seems to me to have a deep 
significance. All the other Turtles, even the Chelo- 
nii, as far as their neck is flexible, bend it in the per- 
pendicular plane of the longitudinal axis of their 
body, in the shape of an S, more or less arched. 
The Pleuroderes, on the contrary, turn it sidewise, 
and conceal it under the projecting edges of the cara- 
pace and plastron, in the same manner as the Birds 
hide their head under the wing. Thus this anatomi- 
cal character excludes the Pleuroderes entirely from 
the natural progressive series which begins with the 
Sphargididaa and ends with the Testudinina, and 
stamps them as a distinct type, bearing among Testu- 
dinata a similar relation to the two sub-orders of 
Chelonii and Amyda?, characterized above, (p. 308,) 
as the Marsupials bear to the placentalian Mammalia. 
There is even this remarkable analogy between the 
representatives of these two classes, that, as among 
the Marsupials and the higher Mammalia the families 
correspond, to a great extent, to one another, so also 
the families of the Pleuroderes recall the families of 
the other Testudinata. The Emydoid form of 
Owen's Chelone Benstedi, from the chalk of Eng- 
land, its small size, and its early appearance in the 
geological series, render the supposition quite plausi- 
ble, that it may as well be a Chelonioid Pleurodere 
as a genuine Chelonioid. At any rate, it has in no 
way the form of a marine Turtle. 
1 See Wagler's Natiirliches System der Amphib- 
ien, p. 214 and 218. 
2 Swainson, (W.,) Natural History and Classifi- 
cation of Fishes, Amphibians, and Reptiles, London, 
1839, vol. 2d, p. 116. The family name ought to be 
spelled Chelydroidae, and not Chelidridae. 342 
AMERICAN TESTUDINATA. 
Part II. 
the outer edge descends steeply from the front margin to about midway, and 
rises from thence backward, but less steeply. Thus the upper surface is a shed- 
roof falling backwards, and curved down on either side, lowest about the middle, less 
and less toward the ends. The arch from side to side is somewhat flattened on 
the top for nearly the whole length of the back. The base, or flattened part of 
the lower surface, upon which the body rests, is very small; it is but little below 
the lowest part of the outer edge; it extends lengthwise from near the front end 
of the body under the whole dorsal vertebral column and a part of the sacrum, 
not reaching the hind end of the body; it is widest about midway, where it 
includes between a third and a half of the width of the lower surface ; from 
thence it narrows to a point behind, and to a blunt but narrow end in front. 
Thus the space around it, that is, between it and the outer edge of the body, is 
very broad, including the greater part of the whole lower surface; it is high and 
steep in front, lower and more horizontal behind. The carapace projects beyond 
the attached surface of the body all round, except where it passes over the neck, 
and where it is joined to the plastron. At the suture with the plastron it is 
turned somewhat down. 
The plastron is fixed, on either side, to the outer edge of the carapace where 
it descends the lowest, about midway between the front and hind ends, from the 
arch of the fourth to that of the sixth pair of ribs, sometimes extending a little 
beyond, and sometimes not quite reaching, these bounds ; from thence inward it 
descends a little, and narrows very fast toward the base, or flattened part of the 
lower surface, where it lengthens again much faster, and spreads out under the whole 
of that surface, and as the free edges do not project, they take its form and size. 
Thus the whole plastron is small. The bridge which passes from its lower flattened 
part to the carapace is extremely narrow; the openings in the shield for the 
protrusion of the head and limbs at the ends of the body are large, including much 
the larger part of the whole lower surface; the front opening is high and exposed, 
and the hind one low under the body, and protected ; these two openings are 
separated from one another on each side only by a narrow isthmus. 
The shield in the adult is completely ossified, and the bony derm is regularly 
divided into plates, and more intimately connected with the true skeleton than in 
the Trionychidm. In the carapace, the eight costal plates, the vertebral row, and 
the marginal rim, are constant. The vertebral row is continuous from one end of 
the carapace to the other; it consists of twelve plates in all, eight of which corre- 
spond to the costals, and lie between them, being fixed to the vertebrae below; 
one reaches from the first of these forward between the first pair of costals into 
the marginal rim, terminating it in front; three more carry the row back to its 
hind end, the last one entering into the marginal rim, and terminating it behind. Chap. II. 
THE CHELYDROIDJE. 
343 
The marginal rim consists of eleven pairs, besides the odd ones at the ends, just 
mentioned. In the plastron there are nine plates, four pairs and one odd one. 
The second and third pairs unite with the marginal rim, form the narrow bridge, 
and then, stretching out lengthwise, form the larger part of the whole plastron. 
The first pair meet at the front end before the attachment of the shoulder 
apparatus, under the neck, where they are broadest, and then growing narrow, 
reach backward and outward and overlap the outside of the second pair. The odd 
plate is quite small; it is situated just back of the first pair within their angle, 
and sends a slender slip back some distance between the inner edges of the 
second pair. The fourth pair meet under the pelvis, terminating in a point just 
behind it, and reach forward and outward and overlap the third pair; they are 
broad where they meet, and grow narrow forward. 
The scapular arch is high, and nearly perpendicular ; it is much higher than 
broad, so that the shoulders are not nearly as wide apart as in the Trionychidse, and 
not so near the outer edge; the coracoid process, the acromion, and the scapula 
are all long, especially the latter; the coracoid process is broad at its ends. The 
sacrum is broad; the iliac bones reach far forward, and approach each other as 
they descend from the sacrum, so that the hip joints are placed under the body far 
inward of the outer edge of both the end and the sides of the shield; the pubis 
and ischium reach steeply downward, and the processes of the pubis, which are 
long and strong, reach downward and forward, and not sidewise. The legs and feet 
are large and strong, the toes are stout, and all but the outer one of the hind 
feet terminate in long, curved, sharp, strong claws; they are freely flexible, but 
not capable of being spread nearly as wide apart as those of the Trionychidse, 
and the web is much smaller, the whole foot being more compact than in the 
latter family. 
The dorsal vertebral column is deep from the shield downward, and there is a' 
large space for the longissimus dorsi on either side of it above the ribs for its 
whole length; the size of this space is connected with the flattening of the shield 
above. The isolated true bone, situated at the front end of the body, is quite 
distinct and prominent; it sends long, slender arms on either side under the mar- 
ginal rim, as far back as to the ends of the second pair of ribs. 
The neck is long, flexible, and stout, and has a powerful muscular apparatus. 
The tail, or, more properly speaking, that part of the vertebral column which extends 
behind the sacrum,1 is very long and strong, much longer than the column between 
it and the neck. This is the case in the American genera, at least. 
1 The great length and strength of that part of 
the vertebral column which extends beyond the sa- 
crum is not simply to be considered as relating to 
the size of the tail ; the part which this region 344 
AMERICAN TESTUDINATA. 
Part II. 
The head is large; it is narrow about the nose and eyes, but grows rapidly 
broad backward to the ear region. The floor of the skull, that is, the roof of 
the mouth and the base of the brain-box, taken as a whole, is on nearly a hori- 
zontal plane; the top of the skull in passing forward over the brain descends 
as steeply, and in Gypochelys Temminckii much more steeply, than in passing over 
the front part of the head, so that we have here none of the angle which in 
the Trionychidse is caused by the turning down of the front part of the skull. 
The ear region is broad from the brain-box outward, but short from behind for- 
ward. The mastoid is short ; its hind surface reaches more upward than back- 
ward, and the os quadratum below descends in nearly a line with it; thus the back 
of the head is high, broad, and square. The crest on the brain-box is high. 
The pterygoids are narrow, and their edges are deeply concave. The breadth of 
the ear region, the height of the crest, and the narrowness of the pterygoids, unite 
to give room for the attachment and passage of very large temporal muscles. 
The arch from the ear to the eye, made up of the jugal, postfrontal, and tem- 
poral bones is broad; the parietals project sidewise, and, for some distance back of 
the eyes, unite with the postfrontals in making a continuous arch over the head; 
moreover the openings for the eyes and nose are small. Thus the head is much 
more protected by bone than in any other family of the sub-order, but much 
less than in the sea Turtles, for there the bony arch reaches to the hind 
extremity of the head, whereas here the ear region is exposed from above. The 
sphenoid is short, and does not extend nearly the whole length of the pterygoids. 
The jaws are strong ; they have sharp alveolar edges, and are pointed at the 
symphyses. 
The free skin is loose, and very movable on the neck and limbs ; it does 
not close around the legs above the knees and elbows, and below incloses them 
'only loosely. The shield is covered with large horny epidermal scales, the arrange- 
ment of which presents rather generic than family characters, especially those of 
the plastron. The free skin, where it is most exposed, especially on the under 
surfaces of the limbs, on the whole front limbs below the elbows, on the neck 
just behind the head, and on the tail, thickens at numerous points into a kind 
of tubercles, and on these tubercles the epidermis is hardened into a kind of scales. 
of the body takes in locomotion, in this family, re- 
minds us rather of the character of the whole ver- 
tebral column in the other Reptiles, in which it con- 
stitutes the principal organ of locomotion. Thus we 
have here a character which is rather Reptilian than 
Chelonian ; and this coincides remarkably with the 
comparatively greater length of the tail in all the 
Testudinata during their earlier stages of develop- 
ment. This resemblance of the Chelydroids and 
other Reptiles is no doubt hinted at in the vernac- 
ular name under which the most common North 
American species is known all over the southern 
United States, where it is called Alligator-Couta, 
from the similarity of its tail to that of an Alligator. Chap. II. 
345 
THE CHELYDROIMh 
On the legs some of these tubercles are enlarged, and their scales form sharp 
projecting ridges ; along the top of the tail there is a row of very strong and 
large tubercles of this kind, and there are many other large ones about the tail 
generally, forming on some parts of it a continuous covering. 
The animal lives mostly in the water, but makes considerable passages over- 
land. It does not, like the Trionychidm, remain burrowed in the soft muddy 
bottom, but rather lies in wait for prey under shelving banks, or among the reeds 
and rushes. It moves over the bottom with long strides, touching it with the 
feet, and also striking the water with the broad surface of the feet and of the 
legs. Both in the water and on dry land, the limbs move in a much more 
nearly perpendicular plane than in the Trionychidm, and the body is raised high 
from the ground; on dry land, a considerable part of the weight of the body 
thus raised is borne by the long, strong tail, which reaches down to the ground. 
When the animal is at rest, the elbow is brought up and back, and a little inward; 
the forearm is turned down, and the flat of the foot rests on the ground; the 
knee is carried forward but little upward, the leg below the knee is turned back 
upon the femur, and the foot again turned forward, resting on the ground ; the 
neck is withdrawn so as to carry the back part of the head under the carapace; 
the tail is bent to one side. See Pl. 4 and 5. In this position, the head, the 
limbs, and the tail are ready for action, the hind pairs of limbs well protected 
by their position under the body, and all withdrawn nearly as far as they can be. 
When danger approaches, the animal does not try to withdraw its head and limbs 
further into the shield, but resorts to a more active defence. It faces the attack, 
raises itself upon the legs and tail, highest behind, opens widely the mouth, and, 
throwing out the head quickly as far as the long neck will allow, snaps the jaws 
forcibly upon the assailant, at the same time throwing the body forward so pow- 
erfully as often to come down to the ground when it has missed its object. As 
far as regards the will of the animal, this is almost the exclusive mode of defence, 
for it is slow to retreat, and cannot withdraw entirely into the shield. It catches 
its prey in a similar way, by throwing the head forward. 
Many of the most important distinguishing characters of this family may clearly 
be traced to its peculiar habits. For example, the height and exposed condition 
of the front end, the descent of the shield behind, the position of the limbs and 
consequent form and small size of the plastron, the breadth of the hind part of 
the head, the strength of the neck and of the longissimus dorsi, the consequent 
flattening of the upper surface over the latter, and the size of the tail; indeed, 
nearly all the prominent characters given above are plainly connected with the 
most marked peculiarity in the mode of life of the family, namely, the defence 
by action with the jaws, instead of a quiet retreat into the shield. 346 
AMERICAN TESTUDINATA. 
Part II. 
There is something fierce and defiant in the attitude of these Turtles, at the 
moment they raise themselves to dart at their enemies, or to seize upon their 
prey. They are as ferocious as the wildest beast of prey ; but the slowness of 
their motions, their inability to repeat immediately the attack, their awkwardness 
in attempting to recover their balance when they have missed their object, their 
haggard look, and the hideous appearance of their gaping mouth, constitute at such 
times a picture as ludicrous as it is fearful and revolting. Their strength is 
truly wonderful. I have seen a large specimen of Gypochelys Temminckii bite 
off a piece of plank more than an inch thick. They take hold of a stick with 
such tenacity that they may be carried for a considerable distance suspended to 
it free above the ground. Their food consists entirely of aquatic animals; fishes 
and young ducks are their ordinary prey. They lay a considerable number of 
spherical eggs, from twenty to forty and more, which they deposit not far from the 
water, in holes which they dig themselves, with their hind legs, upon sloping banks. 
These eggs are rather small in comparison to the size of the animal, about the 
size of a small walnut. Their shell is not brittle, nor is it as flexible as that 
of most of the other Turtles. 
SECTION VII. 
THE FAMILY OF CINOSTERNOHLE. 
Under the name of Sternothserina, Th. Bell has described a group of fresh- 
water Turtles1 which embraces three distinct types so widely different, that, in the 
present state of our knowledge of these animals, they cannot be arranged together 
upon any consideration. One of these types is the African genus Sternothaerus, 
which belongs to the Pleuroderes,2 and for which the family name proposed by 
Bell must be maintained, as a matter of course. The second type is that of 
the genus Cistudo, which truly belongs to the family of Emydoidse, as will be 
shown in the next section. The third type embraces the genera Cinosternum, 
Spix., and Staurotypus, Wagl., which are the leading representatives of the family 
of Cinosternoidse, as characterized below. In the same year in which Bell char- 
acterized the genus Sternothaerus, J. E. Gray distinguished also a section in the 
family of Emydoidse, under the name of Terraphenina,3 which corresponds exactly 
1 Zool. Journ., vol. 2, 1825, p. 299. 
2 See, above, p. 338, note. 
8 Ann. of Philosophy, 1825, vol. 10, p. 211. The 
name ought to be written Terrapenina. Chap. IL 
THE CINOSTERNOIDAE. 
347 
to the Sternothaerina of Bell. As the name of that group is derived from the 
genus Terrapene, Mer., which at that time was restricted by Gray to the common 
Cistudo of the United States, it applies as little to the family of Cinosternoidae 
as that of Bell. Major LeConte, in his late attempt to classify the Testudinata,1 
has also perceived the impropriety of leaving the genera Staurotypus and Cinos- 
ternum among the true Emydoidae, and placed them in his second family with 
Chelydra. Were not the Trionychidae also embraced by him in that family, this 
change would have constituted, in my opinion, one of the most important improve- 
ments recently introduced in the classification of the Testudinata, for Cinosternum 
and Staurotypus are as remote from the true Emydoidm as Chelydra itself, and 
more closely allied to Chelydra than to any other family among the Amydae, 
though they constitute also a distinct family, the characters of which now follow. 
The body is long and narrow. The flattened part of the lower surface upon 
which it rests is much larger than in the Chelydroidae, occupying at least one half 
of the width across the middle, and continuing broad forward, between the shoul- 
ders, to its front end, and backward, under the pelvis and hip joints, to its hind 
end, so that the space between it and the projecting outer edge of the body 
above is much less in this family. The outer edge of the body is not nearly 
as high at the front end as in the Chelydroidae, yet it descends steeply to about 
midway, but keeps upon nearly the same level around the hind end. The upper 
surface rises along its middle line, from the front end to the middle of the body 
and beyond, to near the seventh dorsal vertebra, from whence it falls steeply 
to the hind end; consequently the body is highest far back of a transverse 
section through the middle of the body; and as the hind end is as broad, or 
broader, than the front, the bulk of the body is also thrown backward. These 
peculiarities will always clearly distinguish the carapace of this family from the 
shed-roof of the Chelydroidae, or the more regularly arched cuirass of the Emy- 
doidae. As the outer edge falls from the front end backward, while the middle 
line rises, the upper surface, in order to reach the margin, has to descend far 
down on either side, except about the front end, and, as the body is never wide, 
it must descend steeply. The outer edge of the carapace is raised, all round, 
considerably above the lower flattened surface of the body. It meets the plas- 
tron, and is sutured to it along the two marginal plates which correspond to the 
third and fourth ribs, and is there slightly turned inward and downward; but 
from this suture, either way about the ends of the body, it projects free, a little 
distance beyond the attached surface, and flares outward. 
The free edges of the plastron, that is, the outer edges, where not joined to 
1 Proc. Acad. Nat. Sc. of Philadelphia, 1854. 348 
AMERICAN TESTUDINATA. 
Part II. 
the carapace, also project beyond the attached surface of the body. As the flat- 
tened surface is so broad here, the bridge which connects it with the outer edge 
of the carapace is much shorter than in the Chelydroidae, and rises more steeply, 
but its ends are less concave, and it is broader. 
The whole shield is ossified. The arrangement of the bony plates is, in some 
respects, quite peculiar. The costal plates are constant, eight in number; the 
marginal plates, too, are constant; there is one odd one at each end, one for 
each costal, and two from the front odd one to the first of those which are 
attached to the ends of the ribs, and one from the last of these to the hind 
odd one, making twenty-four in all. But the vertebral row is deficient; it varies 
in number from five to seven, the last two or three being wanting, so that the 
upper ends of the corresponding costals meet one another, and sometimes the 
front one is equally wanting, so that the first costals meet also. The plastron, 
in the adult at least, is made up of only eight plates, four pairs; for there is 
no odd one, as in all the other families of the sub-order. In consequence of 
the absence of an odd bone in the plastron, the median suture extends without 
interruption from one end of the plastron to the other, dividing it into equal 
halves along the middle line. The two pairs of plates, which reach entirely 
across the body, and are sutured to the carapace, do not make up more than 
one third of the whole length; they are but little longer in the body of the 
plastron than in the bridge from thence to the carapace. The front and hind 
pairs are both broad as well as long; they are generally joined to the other 
pair by a flexible hinge,1 except the hind pair in Ozotheca; but in old age 
these hinges are either partially or completely ossified. The middle transverse 
suture is always thoroughly ossified, and never flexible. 
The fixed part of the vertebral column rises backward with the middle line 
of the carapace nearly to the seventh vertebra, and thence descends steeply. 
The tail is never long and strong enough to aid in bearing the weight of the 
body, as it is in the Chelydroidae. In the males it is much larger and longer 
than in the females, and terminates with a horny nail. 
The body projects farther beyond the upper part of the scapular arch than in 
the Emydoidae, and that arch is carried far back in descending to the plastron, 
so far that the coracoid reaches across the middle transverse suture. The pelvis, 
1 The movable parts of the plastron are thus 
different in their composition and in their attachment 
from those of Cistudo and Emys, inasmuch as in 
Cinosternoidae they swing upon an immovable trans- 
verse beam, consisting of two pairs of plates which 
are soldered to the sides of the carapace, while in the 
Emydoids with movable plastron the hinge divides 
the whole plastron transversely into halves which 
swing upon one another, and the sides of the plastron, 
where they meet the carapace, remain also movable. Chap. II. 
THE CINOSTERNOIDJE. 
349 
too, in descending to the plastron, reaches far forward; it is short across the pubis 
and ischium, and the processes of the pubis extend sidewise rather than forward; 
the iliac bones arch outward, but are about the same width apart at the shoul- 
der joints as at the sacrum. The shoulder apparatus and pelvis approaching each 
other so nearly at the plastron, and filling the intervening space with their mus- 
cles, press the organs of digestion and respiration, and the other viscera, up into 
the carapace. The bones of the shoulder apparatus and of the pelvis, and those of 
the legs and feet, are all slender. The feet are short and round. The toes are 
freely movable, and joined by a web, and the whole foot very flexible within 
itself, and at the joint with the forearm and leg. 
The head is long from the orbits of the eye backward, and short from thence 
forward; it is pointed in front. The upper maxillaries and intermaxillaries retreat 
backward and inward, so as to make the mouth small, and carry it far inward, 
under the head. The outer surface of the lower jaw also retreats in the same 
manner, so that the sides of the front part of the head slant inward from the top 
to the bottom. This makes the lower jaw short, and enables the temporal mus- 
cles to act upon it to advantage. These muscles have a long attachment to it, and 
are themselves very large, so that the bite of the animal is strong. The alveolar 
surfaces are broad, and the edges sharp; the lower jaw always terminates in a 
sharp point. The trough by the side of the brain-box, over which the temporal 
muscles pass, is very long; but the mastoids project but little backward, beyond it. 
The arch from the top of the skull, back of the eye, is very short; thus differing 
essentially from the broad roof of the Chelydroidae. The temporal arch, from the 
ear opening forward, over the temporal muscle, is wide. The maxillaries reach 
back under the jugals to the temporals. The bottom of the skull-box and the 
palate rise continually forward to the nasal region, and approach so nearly to 
the top of the skull as to leave only just room enough for the passage of the 
olfactory nerve. The neck is long, but has not nearly as large a muscular 
apparatus as in the Chelydroidae; it is also much more slender. 
The shield is everywhere covered on the outside with large horny epidermal 
scales, which, in different genera, present considerable differences in their arrange- 
ments, especially upon the plastron. The free skin is loose, and folded around 
the body and limbs; its epidermis is thickened into scales in several isolated 
places on the legs, and under the feet, and there only these scales are contin- 
uous and imbricated. The average, size of the representatives of this family is 
smaller than in any other family of Testudinata. The largest, which is about 
nine inches long, is not nearly as large as the smallest of the Chelydroidm, or 
as the largest of either of the other families; and the smallest Ozotheca, which is 
about four inches long, is not larger than the smallest of the Emydoidse. 350 
AMERICAN TESTUDINATA. 
Part II. 
The animal dwells mostly in the water, but comes out from time to time 
and basks in the sun on the shore, or on any exposed surface, usually in such 
a position that at the first approach of danger it may drop directly down into 
the water, or reach it quickly. The slender legs are ill fitted for travelling 
on dry land, but easily carry the body through the water over its bottom. 
When surprised away from the water, the animal seeks the nearest hiding-place; 
if the danger is close at hand, it quickly withdraws the exposed parts into the 
shield, and, if pressed still farther, it resorts at last to biting, not throwing the 
head quickly and forcibly out as the Chelydroidae do, but stretching it out rather 
slowly towards the assailant, and then snapping the jaws forcibly upon it. The 
manner of withdrawing the legs is very peculiar. The fore legs are carried round 
before the body; the elbow, somewhat raised, is carried directly back by the 
side of the head and neck into the scapular arch, the skin at the same time 
rolling off towards the feet and shoulders, and leaving its muscles as naked as 
those of the neck and scapular arch about it; the forearm is turned back, but 
not quite on to the humerus; the hand is either laid in against the head and 
neck, or turned back on to the humerus. See Pl. 4 and 5. The hind legs are 
withdrawn nearly horizontally, the knees like the elbows, though in a less degree, 
stripped of the skin; the foreleg is turned back upon the femur, and the foot 
again turned forward upon the foreleg. The tail is turned to one side. The 
head is drawn back to within the scapular arch, the skin rolling off from the 
neck, but not folding together before the head, as in the Emydoidae. When the 
plastron is hinged, its ends are raised so that the limbs are pressed still farther 
up into the carapace. 
The food is principally animal, but whether exclusively so or not, I do not 
know. As stated above, the habits of these Turtles are entirely aquatic. Their 
natural dispositions are a singular mixture of shyness and of fierceness. They 
remind us of the Insectivora among Mammalia, the rapacious habits of which 
are also in strange contrast with their small size and feebleness. Their motions 
are also quick, though awkward, and almost feverish. When they bite, they 
strike repeated blows, darting the head only, and not the whole body, as the 
Chelydroidae do, - the short tail, and especially the slender limbs, affording no 
adequate means to throw forward the whole bulk of the animal with sufficient 
force to aid in the assault. 
The Cinosternoidae lay few eggs only, from three to five, which they deposit 
on the shore near the water's edge, in holes dug with their hind legs. The 
eggs have the form of a rather elongated ellipse, with very blunt ends. They 
have a shining glazed surface, much smoother than that of other Turtles. Their 
shell is very thick and brittle, even more so than in the Trionychidae. Chap. II. 
THE EMYDOID2E. 
351 
SECTION VIII. 
THE FAMILY OF EMYDOIDAE. 
Since the genus Testudo of Linnaeus began to be subdivided into minor groups, 
and before the family of Emydoidm was circumscribed within its present limits, 
the fresh-water Turtles have been combined, by different authors, in various ways 
with one another and with the land Turtles.1 J. E. Gray tells us, that Th. Bell 
was the first to consider them as a separate family,2 distinct from the Triony- 
chidae, which, five years later, are still united with them by Wagler.3 At that 
time, however, Gray associated the Chelyoidae with the Emydoidae; and though he 
afterwards separated these two families, the Emydoidae still include the Chelydroidae 
and the Cinosternoidae in his latest publications.4 Fitzinger,5 in 1826, and Wieg- 
mann,6 in 1832, adopted also the family of Emydoidae as distinct from the Trio- 
nychidae or Chilotae, while, in 1836, Canino7 considers it as a sub-family of the 
Testudinidae, as he calls the Amydae, exclusive of the Trionychidae. In 1835, 
Dumeril and Bibron8 unite the Emydoidae and Chelyoidae as one family, under 
the name of Elodites; distinguishing, however, the Emydoidae as Elodites Crypto- 
deres, to which they still refer Chelydra and Cinosternum, from the Chelyoidae, 
which they call Elodites Pleuroderes. 
This is by far the most numerous family in the order, as it includes over 
sixty well known species; it presents also the broadest range of differences in hab- 
its, size, and structure. 
The body rests upon a very broad and long flattened surface. It is high, 
and arched upward both lengthwise and crosswise, highest and broadest about the 
middle. The median longitudinal arch is not regular, but descends more steeply 
as it approaches the ends ; the sides, too, curve more sharply around the ends 
than about the middle ; the outlines, however, have no well defined angles so com- 
bining as to divide the body into distinct regions, but run gradually into one 
another, and the whole carapace is like an overturned elongated bowl. The plas- 
1 Comp. Chapt. 1, Sect. 2, p. 241. 
2 See J. E. Gray's genera of Reptiles in Ann. of 
Philos. 1825, vol. 10, p. 210, where that family 
name is spelled Emydidae. Bell also writes it Emy- 
didae in the Zool. Journ. 1825, vol. 2, p. 302. 
3 Natiirl. System der Amphibien, 1830. 
4 Cat. Brit. Mus. 1844. 
5 Neue Classif. der Reptilien, 1826; under the 
name of Emydoidea. 
6 Handb. d. Zool. 1832. 
7 Chelon. Tab. Anal. 1836. 
8 Erpet. gener. vol. 2d, 1835. 352 
AMERICAN TESTUDINATA. 
Part II. 
tron is very large, underlying the whole lower surface. The carapace is raised 
considerably above the flattened part of the lower surface, and its outer edge, 
where it meets the plastron, is turned abruptly downward and somewhat inward, 
and the adjoining edge of the plastron is turned abruptly upward and somewhat 
outward. The edges meet thus, and are joined from the first to the fifth rib, 
so that a large part of the body, including the bulk of the organs of digestion, 
circulation, and respiration, and situated under the second, third, and fourth, and 
parts of the first and fifth costal plates, is completely encircled by the shield. 
The body itself is broadest here, and narrows rapidly to the ends. The free edges 
of the carapace, that is, the edges which do not meet the plastron, project beyond 
the body, and flare outward; the free edges of the plastron also project beyond 
the body, so that the exposed parts, at the openings about the ends, are protected 
by projections of the shield, above and below. Where the body is entirely encircled, 
the shield fits closely to it; still, on account of the greater expansion of this region, 
the flattened surface of the plastron under it, and the arch of the carapace over it, 
are nearly or quite as broad as they are at the ends, where the edges project. The 
fixed part of the vertebral column is arched for its whole length, its highest point 
being nearly over the middle of the body: the arch, however, like that of the cara- 
pace over it, is irregular, descending more steeply near the hind end, but the point 
where the change takes place is hardly, if at all, perceptible; indeed the change 
is but slight, and the whole may be considered as one arc, whose cord makes, with 
the lower surface of the body, an angle opening forward. The iliac bones are 
nearly parallel, making the pelvis about as wide across the hip joints as across the 
sacrum; they reach but little forward in descending from the sacrum; the scap- 
ular arch retreats but little in descending, and the coracoid does not reach the 
middle transverse suture of the plastron; the shoulders are wide apart. Thus the 
pelvis and shoulder apparatus do not closely approach one another, as in the 
Cinosternoidae and Cylidroidse; but the viscera within come down on to the plastron 
between them, and the limbs are carried out nearer the ends and sides of the 
body. The legs are stronger than in the Cinosternoidae. The toes vary widely 
with the habits of the animal; in the most aquatic species they are long, joined by 
a broad web, and capable of being widely spread; in those that live on land, they 
are shorter and less flexible, and the web disappears ; but in none are the feet 
stiff enough to raise the weight of the body upon the ends or last joints of the 
toes, as is the case with the fore feet of the Testudinina. 
The sides of the head are pretty regularly curved from end to end, and widest 
apart between the ear and eye openings. The mastoids reach far backward and 
upward, and are long, rounded, and pointed ; the front wall of the ear cavity 
reaches forward as well as outward from the brain-box. The brain-box is con- Chap. II. 
THE EMYDOIDiE. 
353 
nected with the nasal region by a long, narrow sulcus, for the passage of the 
olfactory nerve. The palatines rise continually from the suture with the ptery- 
goids to the prefrontals, but at their front ends they are considerably lower down 
from the top of the skull than in the Cinosternoidae. The prefrontals meet from 
the foramen olfactorium down to the vomer; they retreat below the foramen. The 
upper maxillaries and the intermaxillaries do not, as in the Cinosternoidae, retreat 
in such a manner as to carry the mouth far inward under the head, but are 
more nearly perpendicular, thus leaving the mouth larger; the jugals come down 
between the maxillaries and the temporals, except that sometimes a very narrow pro- 
cess from the former projects back under the jugals, and meets another from the 
temporals. The jaws vary widely, but never terminate in the long, strong, sharp 
points which exist in the Cinosternoidae. 
The shield is not completely ossified till late in life, and the bony plates are 
very constant and regular in their arrangement. The carapace consists of the usual 
eight costal plates on each side, of eight vertebral plates attached to the fixed ver- 
tebrae, and of two more plates not so attached, which continue this row backward 
to the marginal rim; in the rim there are eleven pairs of plates and one odd one 
at each end, making in all, twenty-four marginal plates. The number of plates in 
the vertebral row varies a little, but the row itself is always continuous from the 
odd marginal plate at the front end to the one at the hind end. The plastron 
consists of nine plates, four pairs and one odd one. The first pair lies across the 
front end, before the shoulder apparatus, and under the extended neck; it is the 
shortest and smallest. The second and third pairs, as in the other families, reach 
clear across the body, and unite with the carapace on either side; these two pairs 
are much longer in the body of the plastron than in the bridge which extends 
from thence to the carapace; they make more than two thirds of the whole plastron. 
The bridge sends off from each end a long process, which is fixed into the cara- 
pace above; when the plastron is hinged, these processes are very small, or entirely 
wanting. The hinge, when it exists, is always between the two middle pairs, and 
never, as in the Cinosternoidae, between them and the adjoining pairs.1 When there 
is a hinge, the edges of the carapace and plastron are united by a narrow, flexible, 
unossified dermal ligament. The odd plate is just back of the suture which unites 
the first pair to one another, and between the fore part of the edges of the next 
pair; it sends back a slender, pointed process for some distance over the suture of 
the second pair. The fourth pair lies under the pelvic region ; it is larger than 
the first pair, but smaller than the second or third. 
Large epidermal scales cover the outside of the whole shield, the form and 
1 Compare the note of p. 348. 
45 354 
AMERICAN TESTUDINATA. 
Part II. 
arrangement of which vary somewhat in different genera. The skin of the head, 
neck, limbs, and tail, is all more or less covered with scales, and where the sur- 
face is exposed, when the limbs are retracted, or when the animal is walking, the 
scales are imbricated, and form a continuous covering. 
The habitat varies widely in this family. Nearly all live more or less in 
the water, in marshes and pools, or along the edges of ponds and still streams; 
but one genus, at least, never seeks the water, and with those that do, the pro- 
portion of life passed in that element varies exceedingly; indeed, the family pre- 
sents a gradual series, from those which are almost exclusively aquatic to those 
which live always on land. In swimming, the feet and legs move in a plane 
nearly parallel to that in which the body is moving, that is, horizontal, if the 
animal is moving horizontally. In walking, also, the humerus and femur move 
nearly horizontally, which is made necessary by the great width of the plastron 
under them ; but at the elbows and knees, which move around or beyond the 
edge of the plastron, the legs are turned down to an angle, greater or less, 
according as the body is raised to a greater or less height from the ground; but 
the knee, even when brought farthest forward, is never opened to a right angle, 
as it is in the Testudinina, and the body is not raised up upon the ends of the 
toes of the fore feet, but the whole foot of both pairs is brought to the ground. 
Thus the body is not carried so high as in the Testudinina, and the gait is 
much less firm and steady. When molested, these Turtles resort to the nearest 
hiding-place ; the aquatic species, if near the water, seek that as the first shel- 
ter ; if hindered in this, they withdraw the head, limbs, and tail into the shield, 
and, if pressed still further, they stretch out the head and bite. When they retreat 
within the shield, the head is carried far back between the shoulders, and the neck 
drawn in naked among the viscera; the legs are folded between the inner parts of 
the projecting free edges of the shield, and the tail is turned to one side. 
The knees and elbows do not, as in the Cinosternoidae, slip in naked among 
the viscera, but the skin keeps its position close around them. The humerus is 
carried round before, and almost directly across, the front end of the body, but a 
little raised at the elbow ; the forearm is turned back upon the humerus, and 
the foot upon the shoulder, the toes reaching to the shield where the edges of 
the carapace and plastron meet. See Pl. 1, 2, 3, 4, and 5. The elbows do not 
come together, but leave room between them for the passage of the head. The 
head is often placed between the elbows, but sometimes drawn further back ; in the 
latter case, the skin folds together before it. The femur is carried round by the 
side of the pelvic region, so as to reach almost directly forward, but a little upward; 
the foreleg is turned back upon the femur, and the foot so turned forward that 
the inner edge rests upon the foreleg. When the limbs are in this position, the Chap. II. 
THE EMYDOID^E. 
355 
toes of the hind feet are at or very near the shield where the edges of the car- 
apace and plastron meet, so that the entire surface on each side between the fore 
and hind leg is protected by the bridge which connects the lower flattened sur- 
face of the plastron with the outer edge of the carapace. Thus the retracted 
limbs and the tail are placed nearly horizontally between the projecting free edges 
of the carapace and plastron; but when the plastron is hinged, its ends are raised, 
and they are pushed further upward and inward. 
The size varies exceedingly in this family ; it is larger than in the Cinos- 
ternoidm, and smaller than in the Testudinina. The smallest known species, Emys 
Muhlenbergii, is about four inches long; the largest, Ptychemys rugosa and concinna, 
are about fifteen inches long. The largest species are among the most aquatic. 
None of the species catch active prey, or are in any way ferocious ; they 
are indeed entirely harmless, and only when hard pressed defend themselves by 
biting; they do not, however, snap repeatedly with the head against their assailants, 
as the Cinosternoidm do. Their food is both vegetable and animal; the latter they 
tear with the jaws, holding it down, when necessary, with the fore feet. In cap- 
tivity, they are very fond of worms, and green leaves, and berries; the more ter- 
restrial species feed upon grass. 
The Emydoidfe, like all other Turtles, lay their eggs upon dry land, in holes 
which they dig themselves with their hind legs. The number of eggs they deposit 
at one time varies more, with different species, than in any other family. The 
more terrestrial species lay the fewest eggs, from two to three, to five or seven; 
while the aquatic species lay many more, from ten to fifteen, to twenty, .thirty, 
and even more. The form of the eggs is that of a more or less elongated 
ellipse; the shell is never brittle, but rather flexible, and less calcareous than in 
most other families. 
The minor differences of form, observed among the Emydoidm, suggest the fol- 
lowing subdivisions, which appear to bear the character of sub-families; but, until I 
have examined a greater number of the species found in South America and in 
the Old World, I do not venture to insist upon the accuracy of their limits. 
1. Nectemydoid.e. The body is rather flat. The bridge connecting the plas- 
tron and carapace is wide, but flat. The hind legs are stouter than the fore legs, 
and provided with a broad web, extending beyond the articulation of the nail 
joint. The representatives of this group are the largest and the most aquatic of 
the whole family. 
2. Deirochelyoidje. The body is higher and more elongated; the bridge con- 
necting the plastron and carapace is not only wide, but at the same time high. 
The plastron itself is narrower than in the preceding tribe. The neck is remark- 
ably long and snake-like, and recalls that of the Chelodinae among the Pleuroderes. 
The feet are webbed. 356 
AMERICAN TESTUDINATA. 
Part II. 
3. Evemydoidje. Differ chiefly from the preceding by the great width and flat- 
ness of the plastron, the narrowness of the bridge which unites the plastron and 
carapace, and the movability of the plastron, at its junction with the carapace, 
and upon itself, owing to a transverse articulation across its middle. The feet 
are webbed. 
4. Clemmydoidal Their chief peculiarity consists in their more arched though 
elongated form, and the more compact structure of their feet, the front and hind 
pairs of which are more nearly equal, and the toes united by a smaller web. 
They are less aquatic, and generally smaller than the preceding. 
5. Cistudinina. The body is remarkably short and high, slightly oblong, and 
almost round. The plastron, which is movable upon itself and upon the cara- 
pace, as in the Evemydoidm, is also connected with the carapace by a narrow 
bridge; but the feet are very different, the toes, as in the Testudinina, being nearly 
free of web. Their habits are completely terrestrial. 
SECTION IX. 
THE FAMILY OF TESTUDININA. . 
The land Turtles are now generally considered as a primary division among 
the Testudinata. J. E. Gray was the first to separate them, under the name of 
Testudinidae, as a distinct family,1 which was soon afterwards adopted by Fitzin- 
ger2 and Th. Bell.3 In 1828, Ritgen changed the name of the family to Cher- 
sochelones.4 In 1830, Wagler6 proposed the name of Tylopodes for this same 
family, which he considers, however, only as a tribe of the one family Testudines, 
to which he refers all the Testudinata. In 1832, Wiegmann6 considers them 
again as a family, which he calls Chersinse, while Canino,7 considering them only 
4 Nov. Act. Acad. Nat. Cur. 1828, vol. 14. 
5 Wagler, Natiirl. System d. Amphibien, 1830. 
6 Handb. d. Zool. 1832. 
7 Saggio An. Vert. 1832; compare also Chelon. 
Tab. Anal. 1836. The family to which Canino refers 
the Testudinina is called by him Testudinidse, and is 
not to be confounded with the Testudinidae, Gray, as 
it embraces, besides the land Turtles, all the other 
Amydae, to the exclusion of the Trionychidae only, 
which he separates as another family coequal with the 
Testudinidae. 
1 Ann. of Phil. 1825, vol. 10. In all his later 
writings, Gray retains the name of Testudinidae ; but 
as Testudo is a Latin noun, it does not admit of a 
patronymic ending. The family name of the land 
Turtles should, therefore, be written Testudinina. 
2 Fitzinger, Neue Classification, etc., 1826, writes 
the family name Testudinoidae ; but in 1836, Syst. 
Anord. d. Schildkr., he adopts Wagler's name, Tylo- 
podes, changing it to Tylopoda. 
8 Bell (Th.), in Zool. Journ. 1828, vol. 3, p. 
419 and 513. He also writes the name Testudinidae. Chap. II. 
THE TESTUDININA. 
357 
as a sub-family, calls them Testudinina. Tn 1835, Dumeril and Bibron1 admit this 
group again as a family, but change the name to Chersites. As this family stands 
at the head of the series, it needs only to be compared with the Emydoidm, which 
are next below. 
As in the Emydoidm, the body rests upon a broad, flat surface, but here it 
continues broad and full much higher up. There is a general equilibrium through- 
out the body; and corresponding parts, between a middle transverse section and the 
two ends, pretty evenly balance one another. The whole form is distinguished by 
the division of its outlines into three well defined regions : a middle region, includ- 
ing the organs of digestion, respiration, and circulation, and extending from the first 
and second pairs of ribs, or, what is the same, from the scapular arch nearly to 
the seventh pair, and two other regions situated at the ends, including and pro- 
tecting the extremities and some adjoining organs. The middle region is very high, 
broad, and long, and forms much the larger part of the body; its sides arch out- 
ward from end to end, but the cords of their arcs are nearly parallel; the top 
is straight, or arched upward ; when straight, it is nearly parallel to the lower 
surface, and when arched, its cord is so. Thus the whole region is quite sym- 
metrical, and its ends are nearly equal, and very large. The anterior and posterior 
regions are comparatively short and small, and the curves which close the ends of 
the body necessarily drop abruptly down, and turn abruptly about them, to meet 
the outlines of the middle region at sharp and well defined angles. 
In most genera, the top and sides of the middle region are only slightly arched 
from end to end; but in Psammobates, and in Cylindraspis, they are so much raised 
as to obscure, at first sight, the distinction between the bulk of the body and the 
ends. Again, the symmetry of the middle region is somewhat disturbed by varia- 
tions in the thickness of the shield, and by a somewhat greater elevation of the hind 
end; but neither of these modifications rises to importance in reference to the essen- 
tial characters of the form; and on examination, the upper surface, divided and spe- 
cialized as it is, is readily distinguished from the simply arched, bowl-like upper sur- 
face of the Emydoidae. The regions at the ends very evenly balance one another 
in bulk, but differ considerably in form ; the front one is shorter and broader 
at the front end, the other more elongated and narrowed toward the hind end; 
the upper surface descends also much lower behind than in front. As in the 
Emydoidse, the openings about the ends, for the protrusion of the extremities, are 
narrow and small. The carapace is raised considerably above the plastron, a 
part of its edges turned abruptly downward and inward, and joined to the corre- 
sponding edges of the plastron, which are turned abruptly upward and outward, and 
1 Erpet. gener. vol. 2d, 1835. 358 
AMERICAN TESTUDINATA. 
Part II. 
the free edges above and below project beyond the attached surface of the body. 
The middle region is the part entirely encircled by the shield. As this region 
is here so predominant, the plastron is longer and broader under it, and its 
suture with the carapace longer, and the openings about the ends shorter, than 
in the Emydoidm. The other parts of the plastron, that is, the parts which under- 
lie the regions at the ends, are comparatively short and small, narrowing rapidly 
towards the ends of the body; indeed, they are so reduced as to appear like mere 
projections; they are both turned out of the general level of the lower surface, the 
front one turned up and the hind one turned down. The hind one does not under- 
lie the whole of its region, but the body projects beyond it all around the sides and 
hind end, so that the opening is outside as well as above it. There is a broad 
space between its outer end and the carapace behind; and, when it is longest, 
this end is deeply notched. The projecting free edges of the carapace flare out- 
ward over these openings. Over the one about the hind end of the body, it flares 
outward considerably at the sides, but less and less backward, until, just behind 
the tail, it continues the steep descent of the carapace above, directly down, and 
reaches nearly or quite as low, and often lower, than the general level of the 
plastron. 
The shield is entirely ossified, and the general arrangement of all the bony 
plates is similar to that which we find in the Emydoidse; but the marginal plates 
are longer, and the two pairs in the plastron which are sutured to the carapace 
larger, than in that family. To meet the neck, the first one or two fixed vertebrae 
are turned down more steeply than the carapace above; the first one is in the 
front margin of the body. Over the middle region, the column follows the general 
direction of the carapace above, and with it turns abruptly down, shortly before 
reaching the sacrum, and continues in its steep descent through the latter, and to 
the end of the tail. As the sacrum is so high up here, the vertebral column below 
is necessarily very long, before it reaches the surface of the body; it protrudes 
but little, and the skin does not close around it till very near the end, so that 
there is only a short, stubbed tail visible. The vertebrae of this part of the col- 
umn are flattened on the upper and lower surfaces. 
The scapular arch is nearly perpendicular, and very high ; the acromion and 
coracoid process are both short, and the shoulders not wide apart ; the humerus is 
broad at the elbow joint, and the tibia and fibula make the forearm broad ; the 
bones of the wrist, hand, and fingers, are all short and compact, and move but 
little upon one another, or upon the end of the forearm. The fingers are all 
close together, down to the last joints; these joints protrude free, and are covered 
with flat, sharp nails. When the muscles and skin are attached, the foot is kept 
nearly on a plane with the forearm above, and the whole limb below the elbow is Chap. II. 
359 
THE TESTUDININA. 
either one continuous broad blade, or a club-shaped stump, terminating in flat, spade- 
like nails. The pelvis is long from the sacrum downward, and short from behind for- 
ward, over the pubis and ischium; it is wider across the hip joints than across the 
sacrum. It will be noticed, that the dimensions of the pelvis and shoulder appara- 
tus agree with the proportions of their regions of the body, which are both high and 
short. The bones of the feet and ankles are short and close together, the last joint 
of the four inner toes only protruding free; these joints are covered with sharp 
nails, narrower and more pointed than those of the fore feet. There is little move- 
ment between the bones of the feet and ankles upon one another, or upon the 
end of the foreleg; the foot is turned forward at the ankle, and the nails turned 
down; and, when the muscles and skin are attached, the whole limb below the 
knee is club-shaped, largest at the bottom, resting on a flat, round base, and having 
four nails protruding forward and downward from the front part of its lower 
edge. 
The end and sides of the front part of the head are high. The nasal region 
is broad, and the eyes wide apart. The nasal cavity reaches back, at the top, 
with its whole width, to the brain cavity, which is also wide here, and the two are 
separated from one another by a thin, narrow strip of bone, which is perforated 
by the foramen olfactorium; below this narrow strip the prefrontals do not meet, 
and there is a large round opening between them, above the vomer. These two 
cavities fill the upper part of the wide space between the eyes, but below they 
recede from one another, and the space between them is filled by the palate, 
which is raised high up at its back end, and continues so to the prefrontals, 
arching somewhat on the way. The alveolar margin is turned directly down- 
ward, and terminates in a sharp edge ; the alveolar surface within is occupied 
by two other ridges, and the intervening furrows; one of the ridges on the inner 
edge, and one between it and the outer. The lower jaw is high, its alveolar 
surface narrow, with sharp edges, and both turned up so as to leave a trough 
between, which, when the jaws are closed, fits on to the middle ridge of the 
upper jaw. The front wall of the ear cavity does not reach so far forward, at 
its outer edge, as in the Emydoidse. The mastoids are short and blunt, and 
reach no farther back than the occipital condyle, so that the hind part of the 
head is broad and flattened. 
The shield is entirely covered, on the outside, with epidermal scales, and the 
skin is everywhere more or less protected with them; and on the most exposed 
parts they are thick and stiff, and form a continuous hard covering, much more 
impenetrable than in the Emydoidm. The parts thus protected are the top and 
sides of the head, the front surface and the edges of the front legs, from the elbow 
down to the finger nails, and up a little way toward the shoulders, the' bottom 360 
AMERICAN TESTUDINATA. 
Part II. 
of the hind feet, and over the heel, and a little way above the back surface of 
the hips, and the space intervening between them, and over the upper surface 
of the tail. 
The size in this family is greater than in any other of the sub-order. The 
Gallapago Turtle, Cylindrapis indica, may be rated at about three feet, the African 
Coui, Psammobates radiatus, at eighteen inches, the South American Chelonoides 
tabulata at fifteen, our Gopher, Xerobates carolinus, at twelve, and the common 
European land Turtle, Testudo graeca, at eight inches in length. Thus they are 
all comparatively large, - except the European species, which is the smallest of the 
whole family, - and, on the whole, by no means as small as some of the Emy- 
doidse; but the great height and fulness of the body make the relative size still 
much larger than the comparison of their length alone would indicate. 
This family live entirely on dry land ; and when placed in the water, they 
try to walk as if on land, having no true swimming motion. In walking, they 
carry the body high up from the ground; the legs are not spread so far apart, 
and move in a plane more nearly perpendicular, than in the Emydoida? ; more- 
over, as the hands are fixed in the plane of the forearm, the body is raised 
up on the ends of the fingers, or at least upon the last joints ; the hind legs 
rest indeed upon the whole lower surface of the foot but the knee joint, when 
the foot is first brought to the ground, is open to about a right angle, and the 
foreleg, which is always long, is nearly perpendicular, so that this end of the body is 
raised to about the same height as the other. They walk with a firmer and more 
steady gait, and travel for a distance with greater rapidity, or rather less slowly, 
than any other Turtles. The front leg is carried forward, and the sharp, spade-like 
nails being fixed to the ground, the body is pulled toward it, the elbow joint closing, 
and the forearm and humerus approaching one another. The deltoid muscles, which 
do the most in pulling the body forward, are here very largely developed. The 
hind leg is carried round to the side of the pelvis, so that the humerus, then 
nearly horizontal, reaches almost directly forward ; the knee is bent to about a 
right angle, and the whole lower surface of the foot, with the nails, rests upon 
the ground ; then as the body is pushed forward, the angle of the knee-joint 
opens, and the leg straightens out. The simultaneous opening of the knee and 
closing of the elbow keep the body, while moving, steady on one plane, and 
there is here a regularity in the walking motion far beyond that of any other 
family of Testudinata. 
The animal has nothing of the ferocious dispositions of most other families ; 
it always retreats from attack, and will not bite, even when pushed to extremity; 
it first seeks some hiding-place, but if it is hindered in this, and the danger is 
close at hand, it resorts to its shield, and trusts solely to it for protection. The Chap. II. 
THE TESTUDININA. 
361 
head is withdrawn far back, but the skin does not roll off from the neck so far 
as to fold together before it, as in the Emydoidse. The humerus is carried round 
before the body, the knees brought together before the head, and the forearm and 
hand turned back upon the humerus. See Pl. 3. The knees meet before the 
humerus reaches directly across the body, and they are somewhat raised above the 
shoulders, which is made necessary by the rise of the plastron forward, so that 
the humerus reaches somewhat outward and upward, and not exactly across the 
body. The blade formed of the forearm and hand is nearly as broad as the 
opening about this end of the body, and when the knees are brought together 
the opening is almost entirely closed, and the surface of the forearm and hand 
exposed before it. The femur is carried to the side of the pelvis, reaching upward 
as well as forward, so that the knee is raised high up within the carapace ; the 
foreleg is turned down and back upon the femur, and the foot and hip thus brought 
together occupy the whole open space by the side of the plastron, so that the bot- 
tom of the foot and the hind surface of the hip only are exposed. The short, 
stubbed tail is bent directly forward (when longest a little curved) between the 
hips, so as to cover most of the surface behind the pelvis. All the parts exposed 
when the limbs are thus withdrawn are covered with thick, hard scales. 
The food of this family is exclusively vegetable. They seem to prefer the 
succulent stems of plants and fleshy fruits to leaves or grass. I have often seen 
our Gopher gnawing the stumps of cabbage and the apples falling from the trees, 
in my garden, as the squirrels do, holding them between their feet. This vegetable 
diet seems to affect essentially the structure of the digestive apparatus, for in our 
Gopher (the only genus examined) the large intestine is longer than all the rest 
of the alimentary canal, including the stomach and oesophagus, whereas in no one 
of the many genera which have been examined of the families of Emydoidae, Cinos- 
ternoidse, and Chelydroidae, does the proportion reach as high as one to five. The 
lungs are very much larger in the Testudinina than in any other family of the sub- 
order, which is undoubtedly due to the exclusively terrestrial habits of the animal. 
These two peculiarities of structure, the great length of the large intestine, and 
the large size of the lungs, directly traceable to the habits of life, go far towards 
giving the middle region of the body its peculiar size and form. A connection 
will readily be seen also between the proportions of the terminal regions, which 
are high and short, and the manner of walking and of withdrawing the limbs, inas- 
much as the legs move in a plane so nearly perpendicular, and the knee and 
elbow joints are raised when retracted so high up within the carapace. Again, the 
equilibrium throughout the body is clearly connected with the steady, straightfor- 
ward motion in walking. Thus this family exhibits, more closely than any other, 
the direct relation which exists between the form and structure. 362 
AMERICAN TESTUDINATA. 
Part II. 
SECTION X. 
ON THE BRAIN OF THE DIFFERENT FAMILIES OF NORTH AMERICAN TURTLES. 
Ill the description of the families of Testudinata, given in the preceding sec- 
tions, only such structural features have been considered as bear directly upon 
the form of the animal. It would, however, be very interesting to ascertain 
further, how far the form of all the different organs is also characteristic of 
families in general, especially since it has already been shown that the devel- 
opment of some of the organs,1 at least, has an immediate influence upon the 
form of the body; but I have thus far refrained from making such an inves- 
tigation, as it would require more extensive comparisons than could properly 
be introduced in this part of my work. Yet, as I knew, from dissections made 
upon a large scale, many years ago, that the form of the brain is characteristic 
of the different families of Fishes, I have thought it desirable to extend these 
comparisons to the Testudinata, in order not to leave the subject entirely out of 
sight. The result of this comparison coincides fully with that obtained in the 
class of Fishes. It stands proved, that while the form of the brain has no 
immediate bearing upon the form of the skull2 and of the head in general, it 
is yet typical in every family. 
All Turtles agree among themselves very remarkably in the structure of the 
brain. From the large hemispheres, the transverse diameter of which is about 
equal to one half of its whole length, the brain grows narrow forward and 
backward. The relations of the different parts of the brain are remarkably 
constant in the whole order of Testudinata; so much so, that, of all the organs, 
the brain seems the least likely to undergo deeper modifications in one and the 
same group, and therefore to be not only one of the most important organs 
of the Vertebrata, but also one of the most characteristic, in a zoological point 
of view. However much the Turtles may assume, in their external organization, 
characters of the higher Vertebrata, (of Birds and Mammalia, for instance,3) still, 
in relation to the brain, they preserve fully the Reptilian character. Their brain 
remains slender and long. This fact is very striking when we compare the head 
of a Turtle with that of a Mammal or that of a Bird.4 The skull of a Turtle 
1 See Chap. 1, Sect. 11, p. 282. 
2 This result is in glaring contradiction with the 
doctrines of Phrenology. 
8 Comp. Chap. 1, Sect. 18, p. 308-312. 
4 In these, the brain-box is much more distinct 
from the bones of the face and jaws than in Turtles. Chap. II. 
BRAIN IN DIFFERENT FAMILIES. 
363 
is compact, like that of a Mammal, and generally very broad; but the brain-box 
and the brain are slender and small, while in all Mammalia and in all Birds, 
in which latter the skull is often very slender, the brain is broad, short, and 
high. The large development of the muscles, and especially of the bony frame- 
work of the head, and not that of the brain, accounts for the broad form of 
the skull of the Testudinata, the locomotive apparatus of the powerful jaws being 
chiefly placed on the sides of the skull. As we have already given a brief 
sketch of the brain of Turtles in general, when treating on their nervous sys- 
tem,1 we have now only to compare the brains of different families with each 
other. 
In spite of the constancy in the proportions of the brain, in the whole 
order, some differences may be noticed when comparing singly the parts of the 
brain of different families with one another. In the first place, it may be 
remarked, that the two sub-orders described above as Chelonii and Amydae seem 
as well justified by the peculiarities of their brain as by the other characters 
they exhibit. In the sub-order of Chelonii proper, the large hemispheres are 
more cylindrical, nearly as high as broad, and, without broadening and forming 
an outgrowing angle behind, they taper into the posterior part of the brain, the 
corpora quadrigemina; while, on the contrary, in all the Amydae, the hemispheres 
are much more depressed, generally marked with some folds, and always widen 
backwards, so as to form there an abrupt angle with the rest of the brain. 
This is particularly the case in Trionychidae, much less so in Chelydroidae, more 
again in Cinosternoidae, and still more in Emydoidae and in the land Turtles. In 
this respect the latter, the Testudinina, stand next to the Trionychidae, which, as far 
as this point is concerned, seem to rank first. The large hemispheres are nearly 
smooth in Trionyx; in the Emydoids, and still more in Testudo, we see fine folds 
run along them. The corpora quadrigemina are largest in proportion to the hemi- 
spheres, and more longitudinal in Chelonii proper, smaller and more rounded in 
Amydae, and often nearly entirely received into the posterior excavation of the hemi- 
spheres, as in Trionyx. The cerebellum is remarkably high in sea Turtles; it is flat- 
ter and thinner, more like a bridge, over the fourth ventricle, in the Amydae. It is 
remarkably broad in Trionyx and Emys, narrower in Cinosternoidae and in Che- 
lydroidae. In sea Turtles, the fourth ventricle is narrow; broader in the Amydae, 
and very wide in land Turtles. In Trionychidae, Chelydroidae, Cinosternoidae, and 
Emydoidae, the whole ventricle has a constant typical shape; that is to say, it is 
much more slender when compared with that of the land Turtles, and broader in 
front; then follows a contraction, when it widens again, and runs out into a long, 
1 Comp. Chap. 1, Sect. 8, p. 274. 364 
AMERICAN TESTUDINATA. 
Part II. 
pointed angle. This contraction is greatest in the Cinosternoidse, less in Chelydroidse, 
Trionychidae, and Emydoidae. The hind part of the ventricle, which follows the con- 
traction, is very long in Trionychidae, Cinosternoidae, and Chelydroidae, but less so in 
Emydoidae. In land Turtles, the ventricle is very wide; the contraction in the mid- 
dle is nearly wanting, and the whole is very short. In relation to this ventricle, 
Cistudo shows again beautifully its standing as the highest among the Emydoidae, 
and next to Testudo. Its ventricle is broader and shorter than in any other of 
the Emydoidae. The lobi olfactorii are generally very much developed in Turtles, 
and the nervi olfactorii rather strong. They are, however, different in different 
families: longest and most slender in sea Turtles, very short and strong in land 
Turtles, more slender again in Chelydroidae, Cinosternoidae, Trionychidae, and Emy- 
doidae. Accordingly the cavity of the nose also is very large in the herbivo- 
rous land Turtles, smaller in Chelonii proper, as well as in Emydoidae, Cinoster- 
noidae, Chelydroidae, and smallest in Trionychidae,1 in which the sense of smelling, 
in spite of that long, protracted proboscis, seems very little developed, as is gen- 
erally the case in aquatic animals. In Testudo, and in Chelonii proper, the hemi- 
spheres and the nervi olfactorii lie in a thick cartilaginous trough, which extends as 
far as the nasal cavity. This trough is very broad and rather short in Testudo; 
narrow and long, on the contrary, in Chelonii proper, according to the propor- 
tions of the lobi and of the nervi olfactorii. In all the other Turtles that trough 
is much thinner; in some, as in Cinosternoidae, it is little more than a stiff 
membrane. This trough is in fact nothing but a part of the cartilaginous skull- 
box, which remains unossified throughout life. We find also some marked differ- 
ences in relation to the nervi optici. In Trionychidae, the two nerves pierce the 
trough, mentioned above, very near together, so as nearly to touch one another; 
on the contrary, in Testudo the nerves separate widely before they run through 
the skull-box, and the distance between the two holes through which they pass 
is about as great as the breadth of the lobi olfactorii above them. In Cinos- 
ternoidse and Emydoidae (including Cistudo) we find the holes for these nerves 
as near together as in Trionyx; in sea Turtles only they are more distant, 
1 The whole of that long, protracted nose so char- 
acteristic of the Trionychidie, is not so much an 
organ of smelling (as the proboscis of some Mamma- 
lia, the South American Nasua, for instance) as an 
organ of respiration, and probably also of touch. 
These Turtles, while lying in shallow water, stretch 
out their nose from time to time to the surface of the 
water for the sake of breathing; but under the water, 
when moving in the mud, this long proboscis has very 
likely a similar function to the long, protracted pro- 
boscis of the Shrews and Moles, when burrowing 
under ground, and groping for worms and larvae of 
Insects. Trionyx may find its food in the same way, 
which consists in mud shells (as Paludinas and Ano- 
dontas) and larvae of Neuroptera, by feeling about 
with its proboscis. Its fleshy lips, the use of which 
is not yet known, may help in the search, as they 
are movable. Chap. II. 
DIFFERENT MODES OF LIFE. 
365 
though not nearly so much so as in Testudo. After the nerves have passed the 
skull-box, they run, in Trionyx, first sideways in a right angle, and after a short 
while, in a second knee, forward to the eyes. In Testudo they run also side- 
ways in nearly a right angle, but pass into the eyes without forming a second 
knee; in Emydoidae they bend in a wide angle, or rather in a curve, forward 
and sideways; while in Chelydra and Cinosternum they run very much as in Tri- 
onyx; finally, in Chelonii proper they run forward and sideways, as in Emydoidae. 
Though there can be no doubt that the brain is the organ to which all the 
passive and the active manifestations of the psychical life of vertebrate animals 
must be referred, nothing is yet known of the ways in which the peculiar kinds 
of psychical manifestations of an animal are connected with the peculiarities of 
structure of its brain. This is a field hardly touched yet by naturalists, though 
a knowledge of these relations alone can give its deeper value to the morphol- 
ogy of the brain. Comparative anatomists must confess, that thus far the innu- 
merable modifications in the form of the brain of Vertebrata have in no way 
been brought into causal relation with the peculiar psychical faculties of the 
animals in which they are observed. Nay, animals which have entirely different 
habits have sometimes identical brains, for instance, Salmo and Coregonus; while 
others, which hardly differ in their mode of life, present great differences in this 
respect, for instance, Acipenser, and the large species of the Catostomus tribe. 
SECTION XI. 
DIFFERENCES IN THE MODE OF LIFE OF TESTUDINATA. 
A knowledge of the mode of life of animals is generally considered as fur- 
nishing, at the outset, a test of their internal organization, and the means of 
ascertaining the degree of their affinity. Although this is true in a certain 
sense, the limits within which there exists such a correlation between the habits 
of animals and their structure are not at all defined. Among Mammalia, it 
would seem as if the mode of life coincided with the limits of the orders, if 
we take, as genuine orders, the leading divisions adopted in that class; though 
we find already here frugivorous and insectivorous Chiroptera, *etc. Among Birds, 
the diet is still less restricted to the orders; we find herbivorous and piscivorous 
species in the same family, for instance, among the Ducks. Among Turtles, we 
have seen that the limits, within which the habits, the mode of life, and the 
diet, are the same, coincide with the natural limits of families. The Chelonioidae 366 
AMERICAN TESTUDINATA. 
Part II. 
are all herbivorous, inoffensive, and shy. The Trionychidse, on the contrary, which 
live upon fresh-water shells and the larvae of aquatic insects, are quick in their 
motions, and bite about them like Snakes; while the Chelydroidae, which live upon 
a large and active prey, are as ferocious as the wildest carnivorous beasts. The 
Cinosternoidae, though also carnivorous, are rather active than fierce; the omniv- 
orous Emydoidae are more timid and inoffensive, and exhibit greater diversity in 
their mode of life; while the herbivorous Testudinina have the grave and con- 
fiding disposition of many of the Ruminants, though, owing to their slow motion, 
they have to trust solely to the strength of their covering for defence. But 
this coincidence, between the natural limits of families and the mode of life of 
their representatives, cannot be considered as a general rule obtaining throughout 
the animal kingdom, for among Fishes we find the most diversified habits in the 
same family. Among the Sahnonidse, as limited by J. Muller, who first recognized 
the natural boundaries of that family, there are voracious species, provided with 
strong, pointed teeth, and feeding exclusively upon living prey, such as the true 
Salmons and others which are entirely destitute of teeth and live upon decaying 
organic substances, such as the Coregonus. And yet these Fishes exhibit none of 
those striking differences which we are accustomed to consider as characteristic in 
the structure of carnivorous and herbivorous animals. Neither their alimentary canal, 
nor the large glands, nor the appendices pylorici connected with it, exhibit marked 
differences. This shows how cautious we ought to be in applying the mode of 
life of any animals as a test of their affinity. CHAPTER THIRD. 
NORTH AMERICAN GENERA AND SPECIES OF TESTUDINATA. 
SECTION I. 
GENERAL REMARKS UPON THE NORTH AMERICAN GENERA AND SPECIES OF TESTUDINATA. 
In submitting the North American Testudinata to a renewed critical revision, 
my object is chiefly to show, that, among the representatives of this order, there 
are many genera on this continent which have thus far escaped the notice of 
herpetologists. It is no part of my plan to describe anew the species which have 
already been so well characterized and so fully illustrated by Major LeConte1 and 
Dr. Holbrook.2 It will be sufficient, for the object I have in view, simply to 
enumerate them, to characterize briefly those which may easily be confounded with 
others, and to insert such additional information as I may have collected respect- 
ing their eggs, their young, the variations of their colors, and their geographical 
distribution. With reference to the specific names of the North American Testu- 
dinata, it will be observed that I have not always followed the nomenclature now 
generally received. Whenever I was led to adopt other names than those in 
common use among modern herpetologists, it was only done with immediate regard 
to the inflexible law of priority; and I have availed myself, in this respect, of 
the information I could obtain from the correspondence of Linnaeus with Dr. 
Garden,3 of Charleston, who provided the great Swedish naturalist with so large 
a number of the animals of South Carolina, described in the Systema Naturae. 
I can hardly expect that the new genera I have characterized in this revision 
1 LeConte, North American Tortoises, in Ann. 
Lyceum Nat. Hist, of New York, vol. 3. 
2 Holbrook, North American Herpetology, Phi- 
ladelphia, 1842, 5 vols. 4to. 
8 A Selection of the Correspondence of Linnaeus 
and other naturalists, from the original manuscripts. 
By Sir James Edward Smith. London, 1821-2, 
1 vol. 8vo. 368 
AMERICAN TESTUDINATA. 
Part II. 
of the North American Turtles should at once meet with a favorable reception. 
There are so many naturalists who look upon classification in general, and especially 
upon minor subdivisions, in the system of animals, merely as convenient devices 
to facilitate their study, that any distinction which in tbeir estimation might be 
dispensed with is considered by them as objectionable, and must be so, according 
to their standard, which does not even admit that genera may exist in nature. 
However, as it is one of the objects of this work to show that genera are 
founded in nature, and that therefore the investigation of the genera and all 
the other natural divisions among animals require as careful and minute atten- 
tion as that of species, I would add a few more remarks upon this topic, in 
order to anticipate the objections which may be raised against the subdivision 
of our Turtles into many distinct genera, and to illustrate their value by a com- 
parison with the genera of one order of the class of Birds, - the Birds of prey,- 
with which the Testudinata may fairly be contrasted for their number, and the 
character of their peculiarities. In the first place, the groups called by Dumeril 
and Bibron Thalassites, Potamides, Elodites, and Chersites (without entering again 
into the question already discussed,1 whether they are families or groups of a 
higher order, or partly families and partly sub-orders) may stand a comparison 
with those groups among the Birds of prey which correspond to the old genera 
Vultur, Falco, and Strix, and which are now generally considered as families, 
though the differences among these Birds are certainly not so great, nor even of 
the same kind, as those which distinguish the Chelonii and the Amydae. Indeed, 
the Vulturidae, Falconidae, and Strigidae, when contrasted with one another, exhibit 
rather differences of form than of structure, whilst the peculiarities of the sub- 
divisions of Testudinata cited above are rather differences of structure, which 
amounts to saying, that the differences of the latter bear the character of sub- 
orders, and the groups of Birds mentioned before differ in the manner of fam- 
ilies. And yet nobody objects now any longer to the further subdivision of the 
Falconidae, for instance, into such sub-families as Aquilinae, Eagles, Buteoninae, Buz- 
zards, Falconime, Falcons, Accipitrinae, Hawks, etc. This being the case, who does 
not perceive, that, if the groups Falconidae, Vulturidae, and Strigidae are genuine 
families, they ought not to be compared respectively with a group like the Elodites, 
which embraces animals as different as the Cistudo, the true Emys, the Terrapins, 
the Cynosternum, the Chelydra, the Chelys, the Chelodina, etc.; but that, on the 
contrary, groups like these last, well circumscribed within their natural limits, 
truly constitute families also, corresponding, by their intrinsic value, to the families 
of the Strigidae, Vulturidae, and Falconidae. 
1 Comp. Chap. 1, Sect. 2, p. 242-252. Chap. III. 
GENERA AND SPECIES. 
369 
This is the position which I am prepared to sustain by a further comparison. 
But even if the Thalassites and Amydae were genuine families, and not sub-orders, 
this would not constitute an objection against subdividing them farther into minor 
natural groups, any more than the nature of the type of Falconidae constitutes an 
objection against subdividing them into sub-families like those mentioned above, each 
of which contains still a number of distinct genera. Let us take, for instance, the 
group of our Terrapins, all of which are now generally referred to the genus Emys. 
It contains a great many species, which in the ultimate details of their structure 
differ as much, if not more, one from the other, than any two genera admitted 
among either the Falconidae, the Vulturida?, or the Strigidae. I am willing to stake 
the correctness of my views on this whole subject upon one single case, taking as 
an example Emys rugosa (rubriventris,) mobiliensis, and concinna, (floridana,) which 
together constitute, in my opinion, a natural genus, and comparing them with 
any other natural group of species of this very same type, as for instance Emys 
scabra (serrata,) Troostii, and elegans (cumberlandensis,) taken together as another 
genus; or Emys picta, Bellii and oregonensis; or Emys geographica, and LeSueurii; 
or Emys concentrica, or insculpta, or marmorata, or reticulata, or guttata, or Miih- 
lenbergii, which constitute singly as many natural genera. Any zoologist, who, 
after a thorough comparison of the external characters and of the skeletons of 
the three firstrnamed species, (Emys rugosa, mobiliensis, and concinna,) taking 
especially into account their skulls, their jaws, and their feet, and contrast- 
ing them with those of Emys picta and oregonensis, or of Emys insculpta, or 
any other of the groups of species just named, - any zoologist, I say, who, 
having made such a comparison, would deny their generic difference, must be 
either blinded by prejudice against truth, or incapable by nature of applying him- 
self to higher questions in Natural History. If this be true, it follows that among 
the Testudinata most of the genera contain very few species, and that this order 
affords an excellent opportunity to learn how generic characters may be ascer- 
tained, even without comparing many species. 
These new genera differ in reality in the same manner as Vultur, Cathartes, 
and Gypaetos, or as Pandion, Aquila, and Harpyia, or as Milvus, Pernis, Buteo, 
and Circus, etc., differ one from the other. The same may be said of Chelydra, 
and Gypochelys, of Ozotheca and Cinosternum, etc. I need not enumerate here 
the characters of these genera, which are fully given hereafter in their proper 
places. Moreover, any one who would competently discuss this question, should 
examine specimens of all these species for himself, zoologically and anatomically, 
when he will at least perceive that, in all our systematic works on Herpetology, 
the species of our Terrapins are either placed side by side without any refer- 
ence to their true affinities, or grouped together according to characters which 370 
AMERICAN TESTUDINATA. 
Part II. 
violate every natural relationship. At the same time, a renewed examination 
would afford ample opportunity, even to the most skeptical, to satisfy himself that 
the characters upon which these genera are founded have thus far, for the most 
part, escaped notice, and constitute a real addition to our knowledge, whatever 
be the view taken of the genera themselves. 
As to the families adopted in this revision, they bear to one another exactly 
the same relations as all natural families have to one another in any natural 
order of the animal kingdom. They are consequently more readily distinguished 
by their habitus, as all natural families should be, that is to say, by their form, 
than are the artificial groups thus far called families among Testudinata by any 
special characters assigned to them. Why, according to present classifications, 
Chelydra and Cistudo, for instance, should belong together to the same family 
with our Terrapins, is not any more obvious than why the latter genus should not 
be referred to another group, the Testudinina, for instance; for there certainly are 
as striking differences, and even differences of a higher order, between Chelydra 
and Cistudo, or Chelydra and the common Terrapins, than between Vultures and 
Falcons. The same may be said of Ozotheca and Cynosternum taken together 
when compared with either of them. And I cannot suppose that any naturalist 
will contend that different classes of the same great type of the animal kingdom 
should be classified upon different principles, however great the difference in the 
nature of the characters may be. 
From what I have said in the opening of this section, it might be inferred 
that I consider the North American species of Testudinata as too well known to 
require much further attention and study. I am far from entertaining any such 
opinion. On the contrary, I consider, in general, an accurate knowledge of species 
as of such difficult attainment, that I do not yet venture upon sketching descrip- 
tions of our Turtles, as I understand that specific descriptions should be, even 
though I have already spent years in their investigation. What 1 offer in the 
following pages I wish to be considered merely as contributions towards a fuller 
illustration of this subject. It will still require long and patient studies before 
our Turtles are known as they ought to be, in order to draw a complete pic- 
ture of the habits, growth, and variations of every species.1 
As to the synonymy of the species,2 it is not my intention to swell this vol- 
1 It is one thing to draw up perfect descriptions 
of species, and another and a very different thing to 
write mere diagnoses, or simply to point out the pecu- 
liarities by which closely allied species may be distin- 
guished. Comp. Part I., Chap. 2, Sect. 6, p. 163. 
2 The older synonymy of all the Testudinata 
known at the time of the publication of his work is 
very learnedly discussed by J. D. Schcepff, in his 
Historia Testudinum, Erlanga?, 1792, 1 vol. 4to. For 
the North American species consult Dr. Holbrook's 
North American Herpetology, or Dumeril and Bi- 
bron's Erpetologie generale. Chap. III. 
THE GENUS SPHARGIS. 
371 
ume by publishing full quotations of all the works in which notices respecting 
our Turtles may be found. Every student, who may wish to make himself familiar 
with this branch of our science, will find ample references to all the works worth 
consulting in any general treatise on Herpetology. I have only alluded to the 
subject in detail where I had reasons to dissent from my predecessors. 
SECTION II. 
THE GENUS SPHARGIS. 
The genus Sphargis was first pointed out by Merrem in 1820, under the name 
which is now generally adopted for it.1 With the scanty materials I have on 
hand, I feel it the more difficult to draw up a description of the generic characters, 
as the habits of these Turtles are little known, and all the specimens I had an 
opportunity of seeing in America were adults, thus affording no opportunity for 
an appreciation of the changes they undergo with age. In the study of genera 
it is very important to compare young and adult specimens, as, from the differ- 
ences they exhibit, it is generally possible to ascertain what constitutes generic 
characters, in contradistinction to family and specific characters. As far as I can 
judge from analogy, and by comparison with the genera of the Chelonioidm, the 
following may be considered as generic characters. 
The arch of the top of the skull is highest over the hind end of the brain- 
box, and grows narrower and lower thence forward to the eye orbits. The upper 
surface falls from over the hind end of the brain-box backward; it is depressed 
over the front end of the brain-box. The frontal region falls from the hind end 
forward. The upper edge of the opening of the nasal cavity is nearly on a level 
with that of the eye orbit. The intermaxillaries rise considerably above the level 
of the lower edge of the eye orbit; they are very thick above, and taper to a 
sharp edge below. The edges of the notch of the front end of the alveolar wall 
of the mouth meet the edge of the lateral notch of each side, on the maxilla- 
ries, near the suture with the intermaxillaries. The three notches occupy the 
alveolar edge of that part of the mouth which underlies the nasal cavity. The 
horizontal alveolar surface of this part of the mouth rises steeply forward; it is 
1 In 1828, Fleming called it Coriudo, in imitation 
of the name Testudo; in 1829, LeSueur, in Cuvier's 
Regn. Anim., proposed the new name Dermochelys 
for it; in 1830, Wagler introduced still another name, 
Scytine, in the plates to his Nat. Syst. der Amph., a 
few copies of which bear that lettering; but he finally 
adopted LeSueur's name, changing it however to 
Dermatochelys. 372 
AMERICAN TESTUDINATA. 
Part II. 
very small, being formed on a small ridge projecting inward. From this region 
backward the alveolar edge is sharp, and rises constantly, and the horizontal alve- 
olar surface widens to its hind end, which slants forward, however, to the union 
with the palatines. The alveolar wall of the mouth is turned inward at the lat- 
eral notch on each side, and outward at its hind end, and thus curves irregu- 
larly. The vomer descends just back of the symphysis of the jaw, so as to 
make behind it a deep inverted pit, into which the pointed end of the lower 
jaw fits. The palatines have each two distinct planes, one horizontal and contin- 
uous with the horizontal alveolar surface, the other raised toward the vomer; the 
former begins in front at a point, and widens backward ; the latter rises highest 
and steepest at its front end. The passages from the nasal cavity to the mouth 
are very large. They lie on each side of the front end of the vomer, between 
it and the maxillaries and the end of the palatine. The lower jaw is highest 
near the articulation and the symphysis ; its upper and lower edges draw near 
each other forward till near the front end, where the alveolar edge rises sud- 
denly to a strong, sharp projection, and the lower edge curves down a little. The 
alveolar edge is sharp. The outer surface, at the symphysis, curves outward in 
passing from the point down to the lower edge. 
There are no scales over the skin. None of the fingers project free, and thus 
none have nails. The epidermis over the jaws is not thickened into a horny 
sheath. Upon the ossified derm, the epidermis is very thin. On the neck and 
limbs and tail, the skin is thick and leathery, and its epidermis hard and compact. 
The prevailing opinion among herpetologists is, that there exists only one sin- 
gle species of Sphargis, which is said to occur along the shores of Eastern Asia, 
especially about Japan, in South Africa, about the Cape of Good Hope, and in the 
Atlantic, chiefly in the West Indies and the southernmost coasts of the United 
States, and in the Mediterranean. But, in my opinion, it is not yet by any 
means clearly proved that the specimens observed in these different stations truly 
belong to the same species. Our museums are still so indifferently provided with 
representatives of this genus, that no sufficient comparison has thus far been made 
between individuals obtained in different parts of the world ; and as long as it 
can be shown that the Loggerheads, the green Turtles, and the shell Turtles of 
the Atlantic differ from those of the Pacific, mere descriptions, without the addi- 
tional evidence of direct comparison, are insufficient to settle the question of the 
specific identity or difference of the leather Turtles of the two great oceans. It 
is true that Temminck and Schlegel assert that the Sphargis of Japan1 is iden- 
1 Siebold, (Ph. Fr. de) Fauna japonica. Che- 
lonii elaborantibus Temminck et Schlegel, Lugduni 
© ' o 
Batavorum, 1833, fol. This work contains important 
remarks upon the anatomy of the Testudinata. Chap. III. 
THE GENUS SPIIARGIS. 
373 
tical with that of Europe ; but, in matters relating to the specific distinction of 
Turtles, I am not willing to take as evidence the assertion even of such distin- 
guished zoologists, because they have described several North American species as 
identical, which I know not only to be distinct species, but even to belong to 
distinct genera.1 There can be no doubt, however, that there is only one species 
of Sphargis in the Atlantic and in the Mediterranean, which is universally known 
as Sphargis coriacea, Gray? 
The first author who mentions this species is Rondelet, who, in his work de 
Pisdbus, published in 1554, describes and figures it, under the name of Testudo 
coriacea sive Mercurii, from specimens caught in the Mediterranean. It has since 
been noticed occasionally in the Mediterranean, and upon the Atlantic coast of 
France and of England; but in all I cannot make out more than nine instances3 
of its occurrence in the waters of Europe. Nor has it ever been seen to lay 
its egg and multiply in that part of the world, while it is very common in the 
warm parts of the Atlantic Ocean, especially along its American shores. It breeds 
regularly every year in the spring, on the Bahamas, on the Tortugas, and on 
the coast of Brazil. It occurs less frequently, already, along the coast of Florida; 
it is caught occasionally on the coast of Alabama, Georgia, and South Carolina, 
and only accidentally visits the more northern shores of the United States. It 
has, however, been noticed in the Chesapeake Bay, off Sandy Hook, and in Long 
Island Sound. One specimen, taken in Massachusetts Bay in 1824, is now pre- 
served in the Boston Museum. In 1848, I obtained one specimen myself, caught 
about Cape Cod by Capt. N. Atwood. 
From this critical examination of the localities where this species is found, and 
1 Ozotheca odorata and Cinosternum pennsylva- 
nicum, Xerobates carolinus and Chelonoidis tabulata. 
2 This species exemplifies clearly a point in zo- 
ological nomenclature which seems hardly yet under- 
stood, though it has been frequently debated before. 
Many naturalists still believe, that the authority at- 
tached to the systematic name of a species indicates 
the discoverer or first describer of such a species. 
Nothing can be more remote from the truth. The 
name of a naturalist, attached to the scientific name of 
an animal, indicates only that he is the first who em- 
ployed that binominal appellation to designate such an 
animal. In this case Rondelet was the first who 
described the species, which he calls Testudo cori- 
acea sive Mercurii. When Merrem recognized that 
it constitutes a genus for itself, he called the genus 
Sphargis, but wantonly changed the specific name 
to Sphargis mercurialis. Had he retained the spe- 
cific name under which Rondelet described it, it would 
have been called Sphargis coriacea, Merrem, as the 
generic and specific names together constitute the sys- 
tematic name of any animal. As it happened, J. E. 
Gray was the first to connect the generic and specific 
names, which must take precedence over all others, 
and so the species is for ever to be called Sphargis 
coriacea, Gray, even though Gray neither established 
the genus nor described the species first. 
3 Three times in the sixteenth century recorded 
by Rondelet; once at Cette, mentioned by Amoreux ; 
once at the mouth of the Loine, recorded by Dela- 
fond; twice on the coast of Cornwall, recorded by 
Borlase; once on the coast of Dorset, recorded by 
Shaw; and once on the eastern coast of Italy, re- 
corded by Schweigger. 374 
AMERICAN TESTUDINATA. 
Part II. 
from its frequence in some parts of the Atlantic Ocean, whilst it is only met 
with accidentally in others, it is plain that the West Indies is its home, and 
that it is not indigenous to Europe, since in three centuries it has not been 
observed more than nine times in Europe, whereas it is seen at all seasons 
about the Bahamas.1 This conclusion is strengthened by the fact that it is less 
and less common as we recede from the Floridas northward ; though from time 
to time it is carried north by the Gulf Stream, and cast ashore along the South- 
ern and Middle States, and more rarely as far north as Cape Cod. It therefore 
becomes highly probable, that the specimens seen in Europe, on the coasts of Eng- 
land and France, and in the Mediterranean, had followed the Gulf Stream across 
the Atlantic, and finally landed in regions very distant from their native seas. 
This fact is highly important with reference to the question of the identity of 
the Thalassochelys Caouana, found also on both sides of the Atlantic. 
Judging from the figures of the eastern Sphargis published by Ph. Fr. von Sie- 
bold in his Fauna japonica, taking especially into consideration the form and rel- 
ative size of the head, the emarginations of the jaws, and the relative size of the 
fins, I am inclined to believe that there exists a second species of Sphargis in the 
Pacific Ocean, along the shores of Asia, which wanders southwards, with the Asia- 
tic shore currents, to an extent not yet ascertained. It is also reported by Tem- 
minck and Schlegel that Sphargis is found about the Cape of Good Hope, and 
that young specimens collected in that region, by Dr. van Horstok, are preserved 
in the museum at Leyden. It is further stated by them, that the figures published 
by Wagler are drawn from a young specimen from the Cape of Good Hope, pre- 
sented to the museum of Munich by the museum of Leyden. This being the case, 
the question at once arises, whether these figures represent truly the same species 
as that which occurs in the waters of the Atlantic and in the Mediterranean, 
or whether there exist two other species of Sphargis, besides that of the Atlantic, 
one of which would be peculiar to the Asiatic shores of the Pacific Ocean, and 
the other to the seas bathing the southern extremity of Africa. With the great 
powers of locomotion which these Turtles possess, it is, however, also possible that 
Asiatic specimens find their way to the Cape, and hence to the West Indies ; in 
which case the same species would be found wandering through all the oceans. 
But nothing short of a direct comparison of a series of specimens from each 
locality will settle this question. 
1 Supposing the American specimens to be dis- 
tinct from the European, LeSueur distinguishes two 
species of Sphargis, and calls the American, Dermo- 
chelys atlantica. The young has also been described 
as a distinct species, at first called Testudo tuberculata 
by Pennant, and afterwards referred to Sphargis, as 
Sph. tuberculata, by Gravenhorst. For more special 
references to the authors mentioned above, consult 
Dumeril and Bibron, Erpet. gener., Holbrook's N. 
American Herpet., and Canino's Fauna italica. Chap. III. 
GENERA AND SPECIES OF CHELONIOID^J. 
375 
SECTION III. 
THE GENERA AND SPECIES OF CHELONIOID2E. 
Three well marked genera, belonging to this family, occur along the coasts of 
the United States; namely, Chelonia, Eretmochelys, and Thalassochelys. The most 
important generic characters thus far observed relate to the structure of the 
mouth, and indicate much difference between them, in the manner of eating, and, 
perhaps, also in the kinds of plants upon which they feed. In Chelonia the 
jaws act like straighhedged shears, cutting from behind forward; the mouth is 
bluntly curved about the front end; the outer alveolar edge of the lower jaw 
falls from the angle forward till just at the end, where it rises to a small, sharp 
projection; the bill along this edge is deeply serrated; its teeth act against sharp 
ridges, which cross, from above downward, the inner vertical surface of the bill 
of the upper jaw. In Eretmochelys the jaws are drawn out forward, as it were, 
and the mouth is narrow and long; at the front end the cutting edges of the two 
jaws project toward one another beyond their general level, so that as the jaws 
close, these edges approach each other first at their front and hind ends; the 
cutting edge of the lower jaw is short, as the upper surface is rounded for some 
distance in front of the angle; the cutting edges are sharp, but not serrated. 
In Thalassochelys the jaws are prolonged toward one another at the front ends 
into strong, pointed beaks, but not drawn out forward as in Eretmochelys; as 
the jaws close, they approach one another first at the front and hind ends; the 
alveolar edge of the lower jaw is deeply concave, and rises higher at the point 
than at the angles; the alveolar edge of the upper jaw rises on each side of 
the beak, and curves downward under the eye; the alveolar edges are blunt, and 
not serrated. 
I am not able to express an opinion upon the value of the genera Halichelys 
and Lepidochelys, as I have not enjoyed an opportunity of examining myself 
the species upon which they are founded.1 But I can state that there occur, 
among the fossils of the reefs of Florida, remains of a large marine Turtle 
which differs generically from the other species found alive about the reefs. I 
am indebted for a splendid skull of this Turtle to one of my pupils, Mr. The- 
odore Lyman, of Boston; and I have obtained myself other fragments of the 
1 These genera were proposed by Fitzinger in his 
Systema Reptilium ; Halichelys for the Caretta atra, 
Merr., Chelonia atra, Auct., and Lepidochelys for the 
Chelonia olivacea, Esch., of the Pacific. 376 
AMERICAN TESTUDINATA. 
Part II. 
skeleton from Cape Sable, all of which I shall describe on another occasion. It 
is possible that this Turtle is the American representative of the Halichelys nigra 
of Fitzinger, founded upon the Caretta nigra, Merr., which is said to occur on 
the Atlantic coasts of Europe and Africa. As to the genus Cimochelys, proposed 
by Owen for Chelonia Benstedi, and afterwards abandoned by himself as a generic 
type, I am inclined to consider it as well founded, though, judging from its form, 
I am not satisfied that it is a true Chelonioid.1 
In the genera of this family the whole body is covered with a scaly epi- 
dermis, and on the head where the skin fits close to the bones, on the shield, 
and on parts of the wings, the scales are large and distinct. On the upper 
surface of the head there is one large median scale, surrounded by a row of 
more or less numerous smaller scales, one or two pairs of which reach down from 
that row to the nose. A field of large scales covers the cheek. A thick, horny 
sheath always envelops the alveolar surface of each jaw, the wide space of the 
front part of the roof of the mouth before and on each side of the opening 
of the passage from the nasal cavity, and the whole upper surface of the lower 
jaw about the symphysis. Just back of the bill on the lower jaw there is a 
large scale. On the ends and front edges of the limbs, the scales are large. 
On the inner edge of the wing there is a row of four or five scales, which 
seem to correspond to the quill feathers of a bird's wing. The scales on the 
shield are arranged in regular rows, namely, one row all round the outer edge, 
one row along the median line above, one row on each side of the latter covering 
the costals, and four rows on the plastron, one just within the marginal row, 
and another between this last and the median line, on each side. The marginal 
row terminates, in front, by an odd scale, and behind, by the meeting of a pair. 
The number of pairs in this row varies somewhat in different specimens; in 
Chelonia and Eretmochelys there are, however, usually twelve pairs; in Thalas- 
sochelys there are thirteen. The odd scale at the front end of this row is very 
broad, several times broader than long. The number in the row over the median 
line is four; in the row on each side of this last, four or five, four in Chelonia 
and Eretmochelys, and five in Thalassochelys. The outside rows of the plastron 
consist each of four, the inner, two rows of six scales each; besides, there are 
some large scales under the hind part of the shoulders, and sometimes one or 
more are interposed at either end of the median line of the plastron. 
If we now consider the American genera separately, they may be characterized 
in the following manner. 
1 Compare my remarks about this species, p. 339, note 3, at the close of the note Chap. III. 
GENERA AND SPECIES OF CHELONIOIDJE. 
377 
I. Chelonia, Brongn. (Fitz.) 
The genus Chelonia, when first separated from Testudo by A. Brongniart, 
included all the marine Turtles, even Sphargis. It was next limited to the 
Chelonioidae proper, and in this extension it corresponds exactly to Merrem's 
genus Caretta. Now it embraces only the green Turtles. It was first restricted 
to its present limits by Fitzinger.1 
The head of this genus, thus limited, is high, and continues so forward to 
the frontal region, where the upper surface descends steeply to the nose. From 
the nose down, the outer surface of the end of the bill of the upper jaw is 
curved outwTard; but it is turned back as far below as above. The mouth is 
long, but broadly curved at the front end. The alveolar edge of the bill of the 
upper jaw is straight, or slightly concave at the sides, and slightly notched at the 
front end; it is sharp, but not serrated. The vertical inner surface is broadest 
at the hind end, and narrows thence forward till at the front end a small pit 
in the palate again widens it. The outer edge of the horny roof descends from 
behind forward to the pit above mentioned; the surface within descends from this 
edge inward to a ridge, which ridge has a deep depression at the symphysis, 
is most prominent on each side of the depression, and decreases thence backward. 
The space between this ridge and the outer wall is a furrow, into which the lower 
jaw fits, as well as into the pit in front. Within this ridge the surface is broad, 
and also has a depression at the symphysis; this surface descends to a small ridge 
at its inner edge. The lower jaw is highest at the angle, and falls thence for- 
ward, but at the front end there rises a small, sharp projection. The alveolar 
edge of this jaw is deeply serrated. Within this edge is a furrow, correspond- 
ing to the ridge of the upper jaw, which is widest at the symphysis, and there 
divided by a transverse ridge; it is deepest on each side of that ridge, and fades 
out shortly before reaching the angle of the jaw. The ridge on the inner side 
of this furrow does not descend from behind forward as fast as the outer alve- 
olar edge, and at its front end is as high as the latter; it rises at the sym- 
physis to a sharp tooth, which is, however, almost entirely formed from the 
horny covering. The ridge vanishes with the furrow backward. Its inner surface 
descends a little way, in one slope, and then more steeply to the attachment of the 
tongue. The outer alveolar edge of this jaw is serrated as far back as the hind 
angle of the jaw. When the mouth is closing, this edge approaches the alveolar 
1 Syst. Rept. 1843. It is adopted by J. E. Gray, 
in the same extent, Cat. Brit. Mus. 1844, and by 
Tschudi, in his Fauna peruana, 1845; but Tschudi 
proposes to change the name to Euchelonia. 378 
AMERICAN TESTUDINATA. 
Part II. 
edge above, first at the hind end, and thence forward successively; but, as the 
front tooth is longer than the others, it reaches the plane of the alveolar edge 
above before those which are nearest to it on each side. The whole horny 
surface of the mouth is rough, and its ridges sharp and pointed. As the head 
is high and narrow, the upper surface is small, and the cheeks large; conse- 
quently the field of scales is small on the top of the head, and those on each 
side large. The row of scales encircling the large scale in the middle of the 
skull is regular, and consists of seven scales. This row reaches partly down on 
the sides; below them there is a field of from fifteen to twenty scales on the 
cheeks, not counting the very small ones about the articulation of the jaws. 
In front of the circle of seven scales, there is one pair of long ones, which reach 
down to the nose. 
The body is oblong, broad across the middle, not keeled or flattened above. 
It has a narrow marginal rim. The scales are everywhere thin and flexible, and 
meet edge to edge, being nowhere imbricated. 
Thus far, only two well characterized species of this genus have been noticed; 
the common green Turtle of the Atlantic Ocean, and the mottled Turtle of the 
Pacific. At least, I can only distinguish them in this way; and I must call in 
question the statements which report Chelonia My das, as found in the Indian 
Ocean, the Red Sea, and China, as well as those according to which the mottled 
Turtle, Chelonia virgata, would also occur in the Atlantic.1 
Chelonia Mydas, Schw. The green Turtle of the Atlantic2 is nowhere so common 
as about Ascension, where the largest numbers are caught. It is very common 
on the Bahamas and among the West Indies, especially at Cayman's Island, where 
large numbers breed; also in the Bay of Honduras and Campeachy, and along the 
coasts of Guiana and Brazil. It also inhabits the coasts of Florida, and of the 
southern United States bordering upon the Gulf of Mexico; but it is seldom 
found as far north as the thirty-fourth degree of northern latitude, and is rarely 
caught as far north as Sandy Hook. It is never seen along the coast of New 
therefore be sifted with the utmost care, as it is prob- 
able that the indications of the presence of Chelonia 
virgata in the Atlantic are owing to a confusion in 
labelling the specimens. 
2 The names most frequently applied to this spe- 
cies are Testudo My das, Chelonia My das, Testudo 
viridis, Chelonia viridis, Caretta esculenta, and Che- 
lonia esculenta. For fuller references, see Dumeril 
and Bibron, Erp^t. gener., and Dr. Holbrook's N. 
Amer. Herpetology. 
1 It is not surprising that seamen should mistake 
the two kinds of green Turtles which occur in the 
Atlantic and in the Pacific, as they are closely allied, 
and vary both to some extent in color, so that the 
radiated variety of the green Turtle (Chel. Mydas) 
is often darker and more extensively tinged with 
chestnut brown than the Pacific species, (Chel. 
virgata,) which is occasionally quite as green as its 
Atlantic representative. Statements respecting the 
geographical distribution of these species should Chap. III. 
379 
GENERA AND SPECIES OF CHELONIOIDJE. 
England, nor has it ever been observed upon the shores of Europe. Along the 
coast of Florida, it approaches the shore in the early part of the summer to 
deposit its eggs in the sand; but the statement of DeKay, that they are hatched 
in the course of two or three weeks, is certainly incorrect, as no Turtle develops 
so rapidly. The shortest period of incubation of Turtles' eggs I have ascertained 
to be about seven weeks. Though regularly brought to our markets in the 
season, I have failed to obtain mature eggs of this species, and young recently 
hatched; but Gravenhorst1 gives a good description of the young, and Audubon 
a very interesting and full account of the breeding.2 This species is also reported 
to occur along the Atlantic coast of Africa, from the Cape of Good Hope to the 
Cape de Verd Islands; but I have had no opportunity of comparing specimens from 
these regions. Nor can I give an opinion from personal experience respecting 
the green Turtles of the Red Sea and of the Indian Ocean. Tschudi states that 
Chelonia Mydas occurs on the coast of Peru; but, as he does not say that he 
compared it with Atlantic specimens, it may be the following species. 
Chelonia virgata, Schw. Without entering into the question of the identity of 
the green Turtles all over the immense range of the Pacific Ocean,3 I can state 
that there occurs, along the coast of California, a species of green Turtles which is 
entirely distinct from that of the Atlantic, by its more elevated and more arched 
back, and by the emargination of its sides over the hind limbs. Besides heads 
and paddles, I am indebted for two perfect specimens of this species to my friend, 
Th. G. Cary, Jr., of San Francisco, to whom I already owe so many scientific 
treasures from California. I have thus been able to compare it with the Che- 
lonia Mydas of the Atlantic, from which it certainly differs as species. As far 
as I know, this is the first time that sea Turtles are mentioned from the west- 
ern shores of North America. Mr. Cary informs me that they are found along 
the whole southern coast of California. The only doubt I have left in my mind 
respecting this Pacific green Turtle is, whether it is identical or not with the spe- 
cies described from Malabar and the East Indian Ocean.4 
1 Deliciae Musei zoologici Vratislaviensis, Lipsi®, 
1829, fol. 
2 Ornith. Biogr. IL p. 370. 
3 Green Turtles are mentioned from the Galapa- 
gos, from the whole range of the Polynesian Islands, 
from New Holland, from the Philippine and Sunda 
Islands, from the whole eastern coast of Asia as far 
north as Japan, from the Red Sea and the Indian 
Ocean, and from the eastern coasts of Africa. But, 
whether they belong to one and the same species or 
not, remains to be ascertained by direct comparisons. 
4 These species are described by Dumeril and 
Bibron under the names of Chelonia maculosa, Cuv., 
and marmorata, Dum. and Bibr. Cuvier's Chelonia 
lacrymata is referred by them to Chelonia maculosa. 
I am inclined to admit that my California specimens 
are identical with Chelonia maculosa; but I question 
the specific difference of Chelonia maculosa, Cuv., 
and Chelonia virgata, Schw., and therefore refer them 
under the older name, Chelonia virgata, Schw. For 
reference to these species, see Dumeril and Bibron, 
Erpet. gener., vol. 2, p. 541-546. 380 
AMERICAN TESTUDINATA. 
Part II. 
II. Eretmochelys, Fits. 
The genus Eretmochelys was first noticed by Fitzinger1 as distinct from Che- 
lonia. The head is low; its upper surface is broader than in Chelonia, and 
its descent to the nose less. The mouth is long and narrow. The sides of the 
upper jaw are compressed, and the front end drawn out forward and downward, 
so that its lower edge is in advance of the nose, and below the general plane 
of the edges of the sides. The front end is narrow and blunt, and keeps about 
the same width from the nose down to the lower edge, which, therefore, is not 
pointed, but like the curved edge of a chisel. The edges of the sides are nearly 
straight. The inner vertical surface of this jaw is broad at the hind end, and 
narrows thenceforward for the greater part of its length, but widens for a short 
distance to the front end. This widening at the front end is not caused by a 
pit-like depression in the horny roof, but by a gentle rise of the latter at the 
symphysis. The surface of the horny roof falls from without inward to a ridge, 
which is divided at the symphysis by a deep transverse depression; it is most 
prominent on each side of this depression, and decreases thence backward; from 
the front end backward it approaches the outer wall for some distance, and then 
again recedes from it. The furrow between this ridge and the outer wall is 
widest and deepest at the front end; it narrows to about midway, and then 
widens again to the hind end; but this latter widened part is only a slight 
depression. Within the ridge, the surface rises to its inner edge; it is as broad 
at the symphysis as the furrow; it decreases backward, and vanishes at the hind 
end. The lower jaw is also long and narrow; it is drawn out forward and 
upward at the front end; the alveolar edge of this end is not pointed, but 
curved, and is as high as the angle of the jaw. The alveolar edges at the 
sides are nearly straight; they are not sharp for the whole length, but thick 
1 In his Systema Reptilium, published in 1843. 
In 1844, J. E. Gray, in the Cat. of the Brit. Mus., 
adopted it, but changed the name to Caretta. On 
general grounds of fitness, this name would be accept- 
able, as it is derived from the vernacular name of the 
tortoise-shell, the caret of the French, and the spe- 
cies which produces this valuable article is the type of 
the genus. It might also be said, that, as Merrem ap- 
plied the name of Caretta to all marine Turtles in the 
same sense as Brongniart had applied to them that 
of Chelonia, when it became necessary, in the pro- 
gress of science, to subdivide the sea Turtles into sev- 
eral genera, the name of Caretta ought to have been 
preserved for one of the new genera, as well as that 
of Chelonia. But, the naturalist who first noticed 
these generic differences had the unquestionable right 
to use his own discretion in adopting any well-framed 
name he chose for these genera; and as Fitzinger 
selected that of Eretmochelys for the Turtle which 
produces the tortoise-shell, that name must now be 
retained, and no one has a right to change it here- 
after. Dumeril and Bibron consider this genus 
merely as a sub-genus of their Chelonia, which in- 
cludes all the marine Turtles, except Sphargis. GENERA AND SPECIES OF CIIELONIOID^. 
381 
Chap. III. 
and blunt for some distance in front of the angle. The lower surface of this 
jaw is turned down, at its front end, below its level at the sides. The furrow 
corresponding to the ridge of the upper jaw is broad at the symphysis; it is 
deep below the outer edge, and short, reaching back to where the alveolar edge 
becomes blunt; it narrows from the symphysis backward to a point, and at its 
inner edge rises to a small ridge. The surface within the ridge descends steeply 
and in one slope to the attachment of the tongue. While the mouth closes, the 
cutting edges approach each other first at the front and hind ends. The cutting 
edges are sharp, but not serrated, and there are no teeth or furrows on any 
part of the horny surface of the mouth. The horny bill is stif^ and projects 
unusually far beyond the bone of the jaw. 
The arrangement of the scales on the upper surface of the head is very sim- 
ilar to that of Chelonia, excepting that the row of seven scales, which encircles 
the large middle scale, is more on the top of the head, and extends less down 
on its sides. Two pairs of scales reach from this row forward to the nose. The 
field of scales on the cheek, like the cheek itself, is small, consisting in number 
of from seven to ten scales. 
The body is long, narrow, and oval. The marginal rim descends steep and 
wide over the shoulders, and flares out wide only about the hind end of the 
body. The scales on the shield are thick and stiff, forming hard plates (the 
tortoise-shell of commerce); they are pointed behind, and imbricated, each one 
overlapping the one next behind. The large scales on the inner edge of the 
front limbs are narrower at their outer than at their inner ends, a character 
which seems to be connected with the manner of folding back the limbs. The 
tortoise-shell is obtained from the species of this genus. 
Modern herpetologists admit, in this genus, only one single species,1 which is 
believed to be common to the Atlantic and the Pacific Oceans. Having had 
ample opportunities of comparing specimens from the West Indies with a series 
of young and adults from the South Seas, preserved in the museum of the 
Essex Institute in Salem, I have satisfied myself that the shell Turtles of the 
Pacific Ocean differ specifically from those of the Atlantic. Specimens from the 
West Indies having first been described under the name of Testudo imbricata, 
under which both are now confounded, this specific name unquestionably belongs 
to the Atlantic species. 
Eretmochelys imbricata, Fitz? This species is common in the West Indies, and 
1 Though synonymous with the following species, 
Chelonia Pseudo-Caretta of Lesson is generally con- 
sidered as a nominal species, whilst Kuhl's Chelonia 
multiscutata is unquestionably a monstrosity. 
2 This species is more generally known under the 
names of Testudo imbricata, Chelonia imbricata, Ca- 
retta imbricata. See, for references, Dr. Holbrook's 
N. Am. Herp., and Dum. and Bibr. Erpet. gen^r. 382 
AMERICAN TESTUDINATA. 
Part II. 
extends all over the Gulf of Mexico, and along the coasts of the southern 
United States. I have seen it alive at Key West (Florida); specimens were 
also brought to me from that locality by my young friend, Theodore Lyman, of 
Boston. It is occasionally seen along the coasts of Mississippi, and all along 
the coasts of Texas and Mexico. It is frequent around Yucatan, in the Little 
Antilles, and especially about Jamaica and the Cayman Islands; it extends also 
along the coasts of Guiana and Brazil. Whether the specimens observed by 
Tschudi, on the coast of Peru, belonged to this or the next species, I am unable 
to state; nor do I know whether it occurs on the Atlantic coast of Africa. 
Eretmochelys squamata, Ag) This species is as common in the Indian and Pacific 
Oceans as the preceding in tropical America. It has been observed by Siebold 
on the coasts of Japan; it is already more common in the Chinese waters; it 
is frequent about the Sunda Islands, New Guinea, and Borneo, and in the Indian 
Ocean about the Seychelles. Dumeril and Bibron quote it from Isle Bourbon, 
and Lesson from the low islands of the Pacific. 
Young specimens of Eretmochelys imbricata and squamata are very similar, 
hearbshaped; but while Eretmochelys squamata preserves this form to old age, 
the adult Eretmochelys imbricata is more elliptical. The squamation is also very 
similar; but while Eretmochelys squamata has distinct, though small horny plates 
upon the neck, Eretmochelys imbricata has none, and exhibits only minute folds 
in the skin. The keels upon the large epidermal scales of the shield are much 
more developed in Eretmochelys squamata than in Eretmochelys imbricata. There 
is one median ridge upon the scales of the vertebral row from the first scale 
to the last; in the Atlantic species, only upon the last four scales. There are, 
besides, converging ridges upon all these median scales in Eretmochelys squamata, 
and only upon the last two in Eretmochelys imbricata. In Eretmochelys squamata 
the scales of the costal row exhibit prominent ridges, arising from the angles 
they form with the marginal scales, and extending to the posterior free angle of 
each scale, of which no trace is observable in Eretmochelys imbricata, neither in 
young nor in adult specimens. These ridges are intersected by the lines of growth, 
and have the appearance of a projecting chain. The ridges upon the middle 
rows of the sternal scales are much more prominent in Eretmochelys squamata 
than in Eretmochelys imbricata. The projecting ridges of the scales of the mar- 
1 I adopt, as the specific name of this Turtle, one 
of the synonyms referred by Linnaeus to the preced- 
ing species. I select this in preference to several 
others, such as Caretta nasicornis, Merr., Chelonia 
multiscutata, Kuhl., Chelonia Pseudo-Caretta, Les., or 
Testudo macropus, Wall)., because it is the oldest 
name applied to a Turtle supposed to be identical 
with Eretmochelys imbricata, and also because the 
name squamata is particularly appropriate for a spe- 
cies from which the tortoise-shell is obtained. Chap. III. 
383 
GENERA AND SPECIES OF CHELONIOIDJE. 
ginal row form more prominent points in Eretmochelys imbricata than in Eret- 
mochelys squamata. Less marked differences are further observed in the form of 
the different scales, all of which coincide to show that the Eretmochelys of the 
Atlantic and of the Pacific Oceans are distinct species. 
III. Thalassochelys, Fitz. 
The genus Thalassochelys was established by Fitzinger, in his systematic 
arrangement of the Testudinata.1 The head is low, broad, and flat on top; its 
upper surface descends but little forward, and the nose is placed high, which is 
made necessary by the height to which the roof of the mouth is raised under 
it. The mouth is broad; the jaws are prolonged at the front end toward one 
another to strong, pointed beaks, but they are not drawn out forward, as in 
Eretmochelys. The outer edge of the upper jaw rises on either side of the 
pointed beak, and then curves down under the eye. The vertical inner surface of 
this jaw is very broad at the hind end; it narrows forward to about midway, and 
then again widens to the front end, where it is broadest. The horny surface of 
the roof of the mouth is high at the hind end; it curves down thence to about 
midway, and then rises again to the front end, where it is highest. This curve 
from end to end is uninterrupted at the outer edge; but from this edge the 
surface descends inward and backward for some distance, then suddenly rises, like 
a step in a staircase, and then again curves up gradually inward and backward 
to its hind edge. The part in front of the step can hardly be called a 
furrow, or its inner edge a ridge, for it descends gently, and comprises about 
half of the whole horny roof; there is a depression in its inner edge at the 
symphysis; on either side of this depression, it has more than half the width 
of the whole horny surface. It narrows backward, and before reaching its hind 
end unites imperceptibly with the part in front of the step. It has a pit at 
the front end of the symphysis. The lower jaw is high at the angle, and at 
the front end is drawn out to a long, strong point, which is still higher than 
the angle. The outer alveolar edge, from the angle to the point, is deeply 
concave. The alveolar surface descends steeply inward, is very broad at the sym- 
physis, and narrows backward to the angle. At its inner edge it rises to a 
small ridge, and from the crest of the ridge it descends steeply and on one 
1 Entwurf einer Syst. Anordn. der Schildkrbten. 
Ann. des Wiener Museums, 1836, 4to. It is main- 
tained in the Syst. Amph. of 1843, and adopted by J. 
E. Gray in the Cat. Brit. Mus. 1844, under the new 
name of Caouana. Dumeril and Bibron consider 
this genus simply as a sub-genus of Chelonia. 384 
AMERICAN TESTUDINATA. 
Part II. 
slope to the attachment of the tongue. The cutting edges are blunt and not 
serrated, and the horny surface of the mouth generally smooth. 
The body is very broad across the shoulders, and short from the scapular 
arch to the front end. The marginal rim flares out broad at the hind end, 
and continues so forward nearly to the shoulders. The curve, from side to side 
over the upper median line of the body, is somewhat flattened. There is a 
keel along the median line. The scales are everywhere thin and flexible. The 
head is so flattened above that the circle of scales around the large median one 
on top is almost entirely upon the upper surface. The scales of this circle are 
less regular and more numerous than in the other genera, about twenty in num- 
ber in the specimen examined. There are two pairs between this circle and the 
nose. The field of scales on the cheeks is small, but the number is about the 
same as in Chelonia, namely, from fifteen to twenty. There is one marked pecu- 
liarity in the arrangement of the scales on the shield, namely, an addition of 
one scale to the row covering the costals, on each side of the median row, on 
the upper surface. The additional scale is small, and situated at the front end 
of its row. In the specimens examined there are twenty-seven scales in the 
marginal row, which is one pair more than in the specimens of the other genera 
which could be compared. 
This genus numbers thus far only two species;1 one of which is found in 
the Atlantic and in the Mediterranean, and the other in the Pacific Ocean. 
Thalassochelys Caouana, Fitz. This species is very common along the Ameri- 
can coasts of the Atlantic, from Brazil to the southern United States.2 It is the 
most common species of Chelonioid found upon the coasts of the United States, 
as it is even frequent in latitudes where other species occur only accidentally. 
It breeds usually as far north as the thirty-second degree of latitude, on the 
coast of South Carolina, whence I have obtained large numbers of eggs, through 
the kindness of Hon. J. Townsend, and occasionally even as far north as North 
Carolina and Virginia. It may be seen along the whole coast of the more 
southern States during the breeding season, in Georgia, Florida, Alabama, and 
Mississippi. From Florida I have obtained eggs in every stage of development, 
1 J. E. Gray enumerates a third species, Cat. 
Brit. Mus., under the name of Caouana elongata, of 
which, however, he has only seen one shield. I must 
leave it doubtful whether the species of the Pacific, 
the Chelonia olivacea of Eschscholtz, (Chelonia Dus- 
sumieri, Dum. and Bibr.,} truly belongs to this genus, 
or is to be considered as the type of a distinct genus, 
Lepidochelys, as Fitzinger thinks. 
2 Its most common names are Testudo Caretta, 
Chelonia Caretta, Testudo Cephalo, Chelonia Cepha- 
lo, Caretta Cephalo, Testudo Caouana, Chelonia Ca- 
ouana, Caretta Caouana, Caouana Caretta, etc. For 
references, see Dr. Holbrook's N. Am. Ilerp., and 
Dum. and Bibr. Erpet. gener. With the exception 
of Valenciennes, all zoologists consider the European 
and the American Caouana as identical. Chap. III. 
GENERA AND SPECIES OF CHELONIOID^. 
385 
through the kindness of Mr. I. W. P. Lewis. It is found everywhere in the 
Gulf of Mexico and among the West India Islands, from the Bahamas to Trin- 
idad, and further south along the coast of Guiana and Brazil. The many speci- 
mens I have examined leave no doubt in my mind that there exists only one 
species of this genus in America. But the question now arises, whether the 
Caouana of the Mediterranean is identical with that of America. Unlike Sphar- 
gis, the Caouana is common in Europe; it breeds there as well as in America, 
and unquestionably is at home in the Mediterranean. It would, therefore, be 
highly important to ascertain whether the American Caouana ever crosses the 
Atlantic. This is the more desirable, as Valenciennes has described the European 
Caouana as a distinct species, under the name of Chelonia Pelasgorum.1 The 
more extensive range of this species northward along the coast of the United 
States, might explain its frequence in the Mediterranean, if the Chelonia Pelas- 
gorum is not a different species. If it is distinct, the American species may yet, 
as do some of the American Birds, occasionally appear in the Mediterranean, and 
have been confounded with the European species. There are here four possibil- 
ities, which render renewed investigations and direct comparisons of European and 
American specimens very desirable. Either the European Caouana has come from 
America, following the Gulf Stream, in larger numbers than Sphargis does, and, 
settling in Europe, has become as numerous there as it is on the other side 
of the Atlantic, the reverse course being impossible on account of the direc- 
tion of the Atlantic currents; or, this species, though identical in Europe and 
in America, has originated separately in both hemispheres; or, a closer compari- 
son may show that the European and the American are distinct species; or, 
finally, though the European and the American were distinct species, the Ameri- 
can may, nevertheless, occasionally visit the shores of Europe, as Sphargis does. 
There are other reasons which render a direct comparison of the Turtles of this 
genus from different oceans very desirable. Temminck and Schlegel state,2 that the 
Chelonia olivacea is the same species as the Caouana, which may wander as far 
as New Holland and Japan. Such an ubiquitous occurrence of this species can 
hardly be admitted without more stringent evidence than that alluded to by 
them, especially when such a mode of distribution runs directly against the well- 
known direction of the oceanic currents. 
Audubon states, that the Loggerhead, Caouana, feeds mostly on large conchshells. 
The young of this species, about which more may be found in the following 
section, are figured in Pl. 6, fig. 13 to 32, and the eggs, which are more fully 
described in the Third Part of this work, are represented in Pl. 7, fig. 30. 
1 Expedition scientifique de la Moree, Paris, 1840, fol 
2 Fauna japonica, Chelonii, p. 26. 386 
AMERICAN TESTUDINATA. 
Part II. 
A large species of this family has been found by Professor Francis S. Holmes, 
of Charleston, in the tertiary deposits of South Carolina. Other specimens, from 
the miocene of New Jersey, have been described by Dr. J. Leidy under the name 
of Chelone grandaeva, and others still, from the green sand, under the name of 
Chelone ornata;1 but, whether they belong to the genus Chelonia as now limited, 
or to Thalassochelys, or to Eretmochelys, is not yet ascertained. 
SECTION IV. 
COMPARISON OF THE GROWTH OF THE CIIELONII WITH THAT OF THE AM YD AS. 
The investigation of the general form of young Emydoidae, and a minute com- 
parison with the adults,2 has led to the result, that all Emydoidse exhibit, when 
hatching, a circular form, which grows more and more elliptical with advanc- 
ing age. This law of morphological development does not hold good for sea 
Turtles. On the contrary, they are much longer in proportion to their width, 
when hatching, and then grow gradually broader. The upper shield of Thalasso- 
chelys Caouana, when hatching, has a longitudinal diameter of 0m,045, and a trans- 
verse diameter of 0m,035; a fortnight after, the relation is 0m,04G to 0m,038; 
after twenty-one days, 0m,050 to 0m,042; and in the half grown, 0m,275 to 0m,250. 
This clearly shows a change from a longer to a broader form, just the reverse of 
what is observed in the Amydae. How is this to be understood ? Is the develop- 
ment of the form just the opposite in these two sub-orders, or is it, perhaps, that 
the Amydae have already run through the form of the Chelonioidae while in the 
egg, and appear now round when hatching, to grow again more and more ellipti- 
cal? The inference from this last view of the case would be, that the Cheloni- 
oidae only reach in their highest perfection, namely, in the adult state, (Thalasso- 
chelys Caouana,) the form which the Amydae exhibit when hatching. This view 
is at least sustained by the facts which lie before us; but further comparisons, 
particularly of young Sphargididae, must show whether this is the law. But, before 
considering more fully the evidence thus far collected upon this point, let us 
examine more minutely the peculiarities which our young Thalassochelys Caouana 
exhibits, at the time it is hatched. 
As in the Amydae, the head of the Th. Caouana, when hatching, is exceedingly 
large. The horn by which the eggshell is broken is a solid excrescence of the 
1 Proc. Acad. Nat. Sc. Phila., vol. 5, p. 329, vol. 8, p. 303. 
2 See above, Chap. 1, Sect. 4, p. 290 to 295. Chap. III. 
YOUNG TURTLES. 
387 
upper jaw. On the top of the head there is a globular elevation, which does 
not rest merely in the skin ; the height of the hemispheres of the brain them- 
selves causes the brain-box to rise in this region. The upper jaw shows thus far 
no sign of the hook, which is so largely developed in the adult; on the contrary, 
its lower edge is notched in front. The inner margin of the sheath of this bill runs 
far backward over the palate, even more so than in the adult, filling up the whole 
triangle between the alveolar edges. The lower bill, however, is provided with a 
sharp hook;, running upwards. The nostrils lie and open more upwards than in 
the adult, in which they are directed half forwards. The lower, or rather pos- 
terior eyelid, is provided with a comb-like row of scales, which fades entirely 
away in the adult. The neck is very bulky, and has the same transverse 
diameter as the head. The shape of the back is oval; there is a median exca- 
vation in front for the neck, and two lateral ones for the arms. Behind, the 
carapace tapers backwards, and runs out into a sharp angle. Three rows of tuber- 
cles are situated along the back, converging towards the hind end, one of them 
upon the median, the two others upon the costal plates. (See Pl. 6, fig. 15 and 
16.) These tubercles begin in the anterior margin of each plate, and rise more 
and more in a longitudinal direction backwards. Four similar rows of tubercles 
are seen below, upon the sternal plates, and upon the plates of the bridge. (Pl. 
6, fig. 14.) All these tubercular ridges arise from the thickening of the corium, 
and are not, as one might suppose, merely owing to a bulging of the epidermal 
plates. They all vanish also, sooner or later, in the adult, except those in the 
median line of the back, and two upon the two median rows of plates of the 
sternum. These ridges of tubercles, the conical shape of the whole trunk, which 
is far higher than in the adult and tapers backwards nearly to a point, the round- 
ing and curving of the circumference of the body, instead of exhibiting a sharp 
and flattened margin as we find it in the adult, give to this young Th. Caouana 
a general resemblance to Sphargis which is very striking. This is particularly 
obvious in a cross-section through the trunk. (See Pl. 6, fig. 17.) This shows, 
again, that the Sphargididae have the lowest standing among the sea Turtles, as this 
family preserves, in its adult form, features which prevail in the Chelonioidse only 
during their earlier development. 
The dorsal plates of the Th. Caouana when hatching show, however, the same 
great breadth in relation to the length, that we find in the hatching Amydse; but, 
while in the latter all the plates increase afterwards in length at the expense of 
their transverse diameter, in the Chelonioidaa the median ones only grow longer 
than broad, while the costal ones grow broader and broader. The marginal plates 
vary in number. We find fourteen in a half grown specimen; while in a series of 
young ones their number differs from twelve to fourteen; and again they are of 388 
AMERICAN TESTUDINATA. 
Part II. 
very unequal sizes. The plates of the sternum grow broader as the animal grows 
older, just the opposite of what we see in the A my da1. This is, however, much more 
extensively the case with the two median rows than with the lateral rows of the 
bridge, which latter are nearly as broad in the hatching Caouana as the median 
ones; while in the adult, their transverse diameter is hardly more than one third 
of that of the median ones. The connection of this change of the form of the 
plates with the change of the whole shape of the trunk, as described in this sec- 
tion for the Chelonioidae, and above (p. 294) for the Emydoidae, is self-evident. The 
sculpture of the plates is exceedingly fine in the hatching Th. Caouana. This sculp- 
ture is preserved in some land Turtles and some Emydoidm throughout life, but 
soon fades away in the sea Turtles. As this sculpture of the plates rests merely 
in the epidermal plates, it is not to be confounded with the wart-like excrescences 
which we meet with in the hatching Chelydroidm and Cinosternoidm. The latter 
consist in real thickenings of the corium, which ossify on a very large scale in 
Gypochelys, and are homologous to the rows of tubercles in Caouana which have 
been described above. 
The tail of the young sea Turtles is exceedingly short; not any longer, in pro- 
portion to their size, than in the adult. This, again, is different from what we see in 
hatching Amydse, where the tail of the young is so remarkably long; in the Emy- 
doidae, nearly as long as the whole carapace. If we attempt to give an explanation 
for this strange discrepancy, we are led to the conclusion that it must be owing 
to the circumstance, that, as in young Emydoidm all the four feet serve as paddles 
and the tail acts as a rudder, while in sea Turtles the front feet only are pad- 
dles and the hind feet serve as rudder, the Chelonioidm do not need such a strong 
rudder tail as the young Emydoidae, which have no rudder but the tail, their hind 
feet being paddles. In relation to this use of the hind feet as rudders in sea 
Turtles, we refer to Pl. 6, fig. 13, 15, and 16, which show the green Turtle in a 
swimming attitude. The hind feet of Thalassochelys Caouana, when hatching, are 
very broad, and the front feet also are broader and much longer in comparison 
than in the adult. The claws of the thumb and the first finger are long and 
strong, while in the adult they fade nearly entirely away. 
Having thus described the young Thalassochelys Caouana as the most acces- 
sible representative of the family of Chelonioidae at the time of hatching, and com- 
pared it with the adult as we have before described the changes which the Amydse 
undergo from the time of their birth to adult age, exemplifying these metamor- 
phoses in our common Chrysemys picta, we may now proceed to compare the 
earlier changes which Turtles undergo in the egg, with a view of ascertaining 
how the differences exhibited by the two sub-orders of Testudinata are to be 
understood. Chap. III. 
YOUNG TURTLES. 
389 
There is an early period in the development of the Testudinata,1 when the 
embryo presents the most striking resemblance to that of any other allantoidian 
Vertebrate. At that age the embryo has not the remotest resemblance to a Tur- 
tle. It is then slender, and comparatively much longer than wide. (Pl. 6, fig. 
28-32; Pl. 13, fig. 2-9; Pl. 14, fig. 2a, and 3-9; Pl. 16, fig. 6; and Pl. 18a, fig. 
2 and 14.) There is no sign of the characteristic shield ; the whole body is as 
elongated as that of a young snake of a corresponding age;2 the head is very 
large in comparison with the size of the animal; the eyes, especially, are large and 
prominent (Pl. 14, fig. 3); the trunk is broader forward, and tapers gradually back- 
ward to a long tail; the limbs, when first formed, project only as small rounded 
paddles. (Pl. 6, fig. 28-32.) 
When the shield makes its first appearance, it is only a fold in the skin, 
extending on both sides of the main axis, and converging in front of the body 
and over the tail. (See Pl. 15, fig. 13; and Pl. 6, fig. 26 and 27.) The body 
being still very long, the outline of this fold, when seen from above, has an ovate 
form. The tail of the Caouana, so short afterwards, is still as long as in the 
Amydse, and its feet not longer than those of the Amydse. (See Pl. 6, fig. 24-27.) 
At this age all Turtles resemble one another. I have seen Chelonioidse, Chelydroidae, 
Trionychidae, Cinosternoidse, and a number of species of Emydoidae in this condi- 
tion of development, which could not be distinguished one from the other. 
Gradually the sides widen, so that the preponderance of the longitudinal over 
the transverse diameter is considerably lessened, and the characteristic features of 
the Turtles are brought out distinctly. (See Pl. 6, fig. 10-12, fig. 22-25; Pl. 9c, 
fig. 9-12, 18, 19, and 22, 23; Pl. 14, fig. 1; Pl. 15, fig. 4-6; Pl. 16, fig. 5; and Pl. 
18a, fig. 2. See also Rathke, Entw. der Schildkroten, Pl. 10, fig. 8 and 9.) At 
this stage of the development the young of all the Testudinata have still the same 
form, to whatever family they may belong; but, as far as a dorsal shield is char- 
acteristic of Turtles, they are unmistakable Turtles. That no family difference can 
as yet be perceived is plain from the fact, that the figures here referred to 
represent the young of Chelonioidae, of Chelydroidae, of Cinosternoidm, and of Emy- 
doidm.3 The most remarkable features of this age consist not only in the perfect 
identity of the form, of the limbs, and of the shield, but also in the greater width 
of the anterior part of the shield, and in the great preponderance of the head. 
But now great changes take place. Henceforth the young of different fami- 
1 The earliest stages of development are de- 
scribed in Part III. with fuller comparisons with the 
other allantoidian Vertebrates. 
2 Compare Rathke, Entwickelungsgesch. d. Nat- 
ter, Pl. 1, fig. 3 and 4, with my fig. 4, Pl. 14. 
8 Pl. 6, fig. 22-25, represent the embryo of Tha- 
lassochelys Caouana; Pl. 6, fig. 10-12, that of Ozo- 
theca odorata; Pl. 9c, fig. 9-12, that of Chelydra ser- 
pentina; and Pl. 9c, fig. 18, 19, and 22, 23, that of 
Chrysemys picta. 390 
AMERICAN TESTUDINATA. 
Part II. 
lies present marked differences. The Chelonioidae become Chelonioid; the Chely- 
droidae, Chelydroid; the Cinosternoidae, Cinosternoid: the Emydoidae, however, assume 
specific characters before they take on their Emydoid form. Though the Chelo- 
nioidae do not widen as much in proportion to their length as the representatives 
of other families, the increase in width, as far as it extends in them, takes place 
chiefly in the anterior part of the shield, so that their form becomes more heart- 
shaped (Pl. 6, fig. 18-21); or, what is the same, leans already towards the form of 
the adult.1 The presence of large epidermal scales upon the shield shows already, 
at this early age, that this young sea Turtle must belong to the family of Che- 
lonioidae, and not to that of Sphargididae. In Cinosternoidae, Chelydroidae, and Emy- 
doidae the shield widens more in the posterior part; especially in Cinosternoidse, 
which remain narrow (Pl. 9c, fig. 8) for a longer time than either Chelydroidae and 
Emydoidae, - or, what is the same, the Cinosternoidae assume earlier than either the 
Chelydroidae or Emydoidae a tendency towards their permanent form. The Cinos- 
ternoidae and the Chelydroidae are, moreover, impressed with other characters peculiar 
to their family at an earlier period than the Emydoidae. Thus the peculiar sculp- 
ture of their surface, like the keels of the Chelonioidae, are seen very early. (See 
Pl. 9c, fig. 13-17; Pl. 15, fig. 7; and Pl. 6, fig. 18-20.) The Emydoidae, on the 
contrary, go on widening, (Pl. 9c, fig. 20, 21, and Pl. 10, fig. 2,) and acquire a per- 
fectly circular form, identical with that of the Trionychidae at the time of hatching, 
(Pl. 6, fig. 1-7,) before their most prominent family characters begin to appear. This 
shows plainly that the circular form is only a transient form with the Emydoidae, 
while it marks the closing development of the form of Trionychidae, and is not 
even reached by the Chelonioidae and Cinosternoidae. In Chelydroidae, on the con- 
trary, the circular form is already accompanied by all the prominent family char- 
acters, (Pl. 15, fig. 1-3,) as in Trionychidae, long before they are hatched.2 
1 The legs also elongate early into a form approx- 
imating that of paddles. Pl. 6, fig. 20. 
2 In Part I., Chap. 2, Sect. 8, p. 172 to 176, I 
have already discussed the subject of the successive 
development of the characters in a general way. 
The particular results obtained from the study of the 
Turtles deserve, however, a special notice. We have 
seen that, at a very early period, the embryo of Tur- 
tles presents all the characteristics of a vertebrated 
animal. But, even before it can be recognized as a 
Vertebrate, the germ has already acquired the inde- 
pendence of a new being. It is an individual, free 
from its parent, before it even shows to what branch 
of the animal kingdom it belongs. This exemplifies 
strikingly the importance of individuality as the most 
prominent feature in every organic development. 
But individuality is not only characteristic as the pri- 
mary step in the growth of every living being; it re- 
mains also characteristic through life, so much so in- 
deed, that individual peculiarities are superadded even 
to the highest features of their race, in almost every 
individual, to whatever species he may belong. Thus 
Nature herself teaches us the true value and dignity 
of individuality. This shows plainly how contrary to 
the law of organic growth must be every restraint, 
whether natural or artificial, which does not foster the 
highest development of the species. (Under natural 
restraint, I would consider the influence of physical Chap. III. 
391 
YOUNG TURTLES. 
These facts show plainly, that there is a common plan of development in all 
Testudinata, however much they may differ in their full-grown state, and that 
agents as far as they limit the growth of animals and 
plants; under artificial restraint, that imposed by 
man.) The next step in the development unfolds the 
prominent features of the branch of the animal king- 
dom to which the new being belongs. It marks the 
sphere in which it is to grow up. At this stage the 
plan of the development characteristic of the branch 
is, as it were, laid out, and its direction and ten- 
dency are defined; but the manner in which this is to 
be accomplished remains to be seen in the further 
progress. What unexpected resemblance to the moral 
and intellectual development of Man I 
We might next expect that the mode of execution 
which characterizes classes should necessarily follow, 
but this is not so. Just as in other developments, the 
true character of the structure is frequently not ap- 
parent before it is completed: certain complications, 
which are embodied in it, become visible before their 
relation to the whole can be perceived; the form of the 
structure may also be recognizable before its consti- 
tutive elements can be analyzed; many details in the 
structure, the relative proportions of the parts to one 
another and their relations to the surrounding circum- 
stances, may be fully or partially worked out long be- 
fore the distinguishing character of the structure, as a 
whole, is appreciable. 
This, also, is precisely the case with the develop- 
ment of different animals. In Turtles, which as Rep- 
tiles are cold-blooded, air-breathing, oviparous ani- 
mals, none of the most prominent characters of the 
class are developed before they are hatched, (as, for 
instance, their aerial mode of breathing;) while some 
of these class characters are only recognizable in a 
much later period of life, (their oviparity, for in- 
stance.) Yet, as showing the manner in which the 
plan of structure of their branch is carried out, these 
characters are truly class characters. On the con- 
trary, the special complication of that structure which 
characterizes the order as an order, - the separation 
of the body into distinct regions, a head, a neck, and a 
tail, and the presence of the shield and the four legs, 
which appear very early, even before the animal has 
assumed its form, - shows plainly, that in Testudinata 
the development of the ordinal characters precedes 
not only that of the characters of the family, but also 
that of the characters of the class. Strange as it may 
appear, it is unquestionable that in Turtles the ordinal 
characters are developed before those which charac- 
terize the class. The early separation of the head 
from the neck; the distinctness with which the limits 
between the neck and trunk, and between this and 
the tail, may be recognized, almost as soon as the 
main axis is formed ; and, finally, the early develop- 
ment of the shield and of the four legs leaves not the 
remotest doubt upon this point. 
Next, the form is developed, so that the most 
prominent family character appears immediately aftei' 
the ordinal characters, in all the families of Testudi- 
nata, with the exception of the Emydoidas, and prob- 
ably also of the Testudinina, though these have not 
yet been observed. It is particularly interesting, 
that this character is fully marked in the Chelonioidae, 
Trionychidae, Chelydroidae, and Cinosternoidae long 
before they are hatched; whilst in the Emydoidae it is 
not apparent for a long time, even for years after their 
birth, at a time when they exhibit already most of 
their generic and specific characters. As to the suc- 
cessive appearance of the generic and specific char- 
acters, even limiting the inquiry to the different gen- 
era and species inhabiting North America, much more 
extensive investigations, than I have been able to 
make thus far, are still required, before it can be sat- 
isfactorily illustrated. Meanwhile I refer to my re- 
marks, p. 290-295. The great difficulty in these 
investigations consists in a correct appreciation of 
those peculiarities which may be embryonic and not 
specific, though preserved through life, and enumer- 
ated by herpetologists among the specific characters. 
I can state, however, that I do not know a Turtle 
which does not exhibit marked specific peculiarities 
long before its generic characters are fully developed. 
It is only necessary to compare the mode of devel- 
opment of some of the Articulata with that of the 
Testudinata, to perceive at once how different the suc- 392 
AMERICAN TESTUDINATA. 
Part II. 
the representatives of different families resemble one another more in proportion 
as they are younger. But the peculiarities which distinguish them most promi- 
nently do not make their appearance at the same time. Features which belong 
to a later stage of growth in one family become distinct in other families at a 
much earlier period of life.1 Some stop at one point, while others undergo fur- 
ther changes. Yet, the order in which these changes take place is so uniform, 
that it may furnish the means of determining the relative standing of these ani- 
mals, as soon as it is admitted that the characters which distinguish the earliest 
stages of growth are inferior to those of the mature development. 
The great size of the head and neck is a remarkable feature in all the young 
Testudinata, in no one of which are these parts retractile. The proportions are 
greatly changed afterwards, and the head and neck become retractile in the 
Amyda\ I take it, therefore, that large-headed Turtles, the head of which cannot 
cessive appearance of the characters peculiar to 
groups of a different importance may be in different 
branches of the animal kingdom. In Insects, for in- 
stance, the class characters, - the tracheae and articu- 
lated legs,-appear always before the ordinal charac- 
ters, the wings ; the family characters, - the form, - 
are also fully defined before the ordinal characters 
appear, etc. How different from what we have seen 
in the Testudinata! 
1 A glance at Pl. 1 to G will show to what ex- 
tent the young representatives of some families dif- 
fer in form from the adult, and how early others 
acquire their family characters. All the figures of 
these plates represent young Turtles in their natural 
size at the time of hatching, or as nearly at that 
time as I could obtain them. Yet neither the Che- 
lonioid^e, (Thalassochelys Caouana, Pl. 6, fig. 13- 
16,) nor the Trionychidje, (Aspidonectes spinifer, 
Pl. 6, fig. 1 and 2 ; Aspidonectes Emoryi, Pl. G, fig. 4 
and 5 ; Platypeltis ferox, Pl. G, fig. 3 ; Amyda mutica, 
Pl. G, fig. G and 7,) nor the ChelydroiDjE, ( Chelydra 
serpentina, Pl. 4, fig. 13-16, and Pl. 5, fig. 18 and 
19 ; Gypochelys Temminckii, Pl. 5, fig. 23-27,) nor 
the Cinosternoid^e, ( Ozotheca odorata, Pl. 4, fig. 1- 
6 ; Ozotheca tristycha, Pl. 5, fig. 20-22 ; Cinosternum 
pennsylvanicum, Pl. 4, fig. 7-12, and Pl. 5, fig. 16 and 
17 ; Cinosternum flai'escens, Pl. 5, fig. 12-15 ; Cinos- 
ternum sonoriense, Pl. 5, fig. 8-11,) exhibit marked 
differences in their form from the adults; or, what 
amounts to the same, their family characters are fully 
developed, not only at the time of hatching, but even 
long before. The Emydoid^e, on the contrary,- 
(such as Ptychemys concinna, PL 1, fig. 13, Pl. 2, fig. 4- 
G ; Ptychemys mobiliensis, Pl. 3, fig. 14-1G ; Ptychemys 
rugosa, Pl. 26, fig. 1-3 ; Trachemys elegans, Pl. 3, fig. 
9-11; Trachemys scabra, Pl. 2, fig. 13-15; Graptemys 
geographical Pl. 2, fig. 7-9; Graptemys LeSueurii, 
Pl. 2, fig. 10-12, and'Pl. 5, fig. 5-7; Malacoclemmys 
palustris, Pl. 1, fig. 10-12 ; Chrysemys picta, Pl. 1, fig. 
1-5, and Pl. 3, fig. 4; Chrysemys marginata, Pl. 1, fig. 
G, and Pl. 5, fig. 1-4; Chrysemys oregonensis, Pl. 3, 
fig. 1-3; and Chrysemys Bellii, Pl. 6, fig. 8 and 9; 
Deirochelys reticulata, Pl. 1, fig. 14-1G, and Pl. 2, fig. 
1-3 ; Emys Meleagris, Pl. 4, fig. 20-22; Nanemys 
guttata, Pl. 1, fig. 7-9; Actinemys marmorata, Pl. 3, fig. 
5-8; Cistudo virginea, Pl. 4, fig. 17-19; and Cistudo 
ornata, Pl. 3, fig. 12 and 13,) - have almost perfectly 
circular outlines, and exhibit in no way the slightest 
tendency to the more or less elongated form of the 
adult, with the exception perhaps of Malacoclemmys 
palustris, and Deirochelys reticulata, which are 
slightly oval; so that, at the time of hatching, no 
Emydoid has assumed the form characteristic of that 
family. Xerobates Berlandieri, Pl. 5, fig. 17-19, the 
only young representative of the family of Testudi- 
nina which I had an opportunity of examining, shows 
that these Turtles also are obicular before they as- 
sume their final, characteristic form. Chap. III. 
YOUNG TURTLES. 
393 
be drawn in at all, or only partially, are inferior to the others, or exhibit what 
may be called embryonic characters.1 This is the case in the Chelonii, which have 
always been considered as the lowest Testudinata, and, among Amydae, to some 
extent in the Chelydroidae, which stand very low in their sub-order. In all 
younger embryos the limbs are paddles ; they remain paddles in the Chelonii, 
whilst they are terminated by feet, with more or less distinct fingers, in the 
Amydae. We thus have here an additional evidence that the Chelonii are infe- 
rior to the Amydae. There is, however, a remarkable feature in the development 
of the limbs in Chelonii : the paddles of the young sea Turtle, though identical 
with those of the Amydae, differ from what they are in the adult age, and yet 
they remain paddles. They exhibit, as it were, overgrown embryonic features, 
such as characterize the types which I have called hypembryonic? 
The shield presents similar transformations. At first oblong, and narrower 
behind than in front, it grows gradually broader, assuming even a circular form. 
But the characters of the adult are already impressed upon the shield of the 
Chelonii before it grows very wide ; so it is also with the Cinosternoidae and 
Chelydroidae, while in Trionychidae the flat, roundish form in its fullest expansion 
is that which the adult preserves. The Emydoidae have also reached that circu- 
lar form at the time of hatching, but they afterwards grow again more elongated. 
The question thus arises, Is there a retrograde development in the Emydoidae, or 
not ? For my part, I am satisfied that it is not the case. Considering the differ- 
ence of the elongated form of the Emydoidae, in which the hind end is generally 
the broadest, whilst in the elongated shield of the embryo this is the reverse, 
and considering further the closer relation of the Emydoidae and Testudinina, in 
which latter the two ends of the body balance one another so evenly, I believe 
that the elongation of the Emydoidae, subsequent to their circular outline, marks 
a real progress. I consider, therefore, the later widening of the Chelonii, as observed 
in the adult, as a progressive development, which is attained only late in life in 
that family; so that it might be said, that, in this respect, the Chelonii do not even 
reach in old age the form to which the Trionychidae and Emydoidae attain at the 
time of hatching, and at which the Trionychidae stop, whilst the Emydoidae take 
another start in a higher direction, to approximate the form prevailing in the adult 
Testudinina. A knowledge of the early embryonic changes of the Testudinina is 
still wanting to carry out fully these comparisons. 
I am inclined to consider, further, the presence of keels along the back as 
characters of inferiority, considering the prominence of these keels in the lowest 
Chelonii, the Sphargididae, and their presence in young Chelonioidae, which lose 
1 Comp. Part I., Ch. 1, Sect. 25, p. 112 to 116. 
2 See Part L, Ch. 1, Sect. 25, p. 116. 
2 See Part L, Ch. 1, Sect. 25, p. 116. 394 
AMERICAN TESTUDINATA. 
Part II. 
them more or less completely in old age. Carinated species also are more numer- 
ous among the lower Amydae than among Testudinina; all the Chelydroidm and 
Cinosternoidse are more or less carinated, especially in their younger age, and they 
are inferior to the Emydoidm; many of the most aquatic Emydoidse are also cari- 
nated, some through life, others only in the younger age; and we have already 
seen that the aquatic species are inferior to the terrestrial ones, and that the 
young Emydoidse are more aquatic than the adults.1 
From the few facts which I have already collected,2 I am convinced that much 
valuable information could be obtained from a similar comparison of the changes 
which our common Mammalia and Birds undergo in early life, and that the time 
is not far distant when, in this way, the relative standing of the representatives of 
every family will be determined with remarkable precision. The results to which I 
have arrived by the study of the young Turtles will, I hope, stimulate other nat- 
uralists to turn their attention also to this interesting subject. Happily the time 
is coming when fewer new species are to be found, and, from want of materials 
for their ordinary work of registering animals, with scanty or insufficient charac- 
teristics, zoologists may be led to more important investigations. 
SECTION V. 
GENERA OF TRIONYCHID2E. 
It appears from the statement of Dumeril and Bibron,3 that Schweigger was 
the first to perceive the necessity of separating the soft-shelled Turtles as a dis- 
tinct genus, which he called Amyda, in a paper presented by him to the Acad- 
emy of Sciences in Paris, in 1809. Geoffroy, however, changed that name to 
Trionyx,4 which Schweigger himself adopted when he published his paper,6 as also 
did all herpetologists afterwards. This genus was not further subdivided until 
Wagler showed, in 1830, that it embraced species which exhibit marked structu- 
ral differences, in the connection of the plastron and hind legs, and in the ossi- 
fication of the marginal rim. For those species which have bony plates along the 
margin, and a wide hind lobe of the plastron, he retained the name of Trionyx, 
1 Compare the note to p. 293. 
2 See Agassiz, (L.,) Lake Superior. Boston, 
1850, p. 191; also Twelve Lectures on Comparative 
Embryology, p. 8 and 101. 
3 Erpet. gener. vol. 2, p. 464. 
4 Ann. du Mus. de Paris, vol. 14, 1809. 
5 Prodromus Monographic Cheloniorum ; Ko- 
nigsberg. Archiv, 1812. Chap. III. 
GENERA OF TRION YCIIIDJE. 
395 
and united all the others under the name of Aspidonectes, supposing that the 
soft marginal dilation of the shield assists in swimming, which is only true in as 
far as it forms a sharp cut-water, for it is not moved up and down, as are the 
wings of the Skates. 
The two genera proposed by Wagler have since been adopted by all modern her- 
petologists, who have vied with one another in changing their names, although not 
to the real advantage of science. Thus Dumeril and Bibron, discarding entirely the 
old generic names, call Gymnopus the genus which Wagler had named Aspidonectes, 
and Cryptopus, that for which he had retained the name Trionyx.1 J. E. Gray, 
on the contrary, restored the name Trionyx to the genus which Wagler had 
called Aspidonectes,2 and gave a new name, Emyda, to Wagler's Trionyx. In 
1836, Fitzinger3 introduced further generic distinctions in this family, calling Tri- 
onyx the same genus for which Wagler had retained that name; Aspidonectes, 
the Trionyx javanicus and segyptiacus of Geoffr. and the Trionyx indicus of Gray, 
and proposing three new genera, one under the name of Platypeltis for the Tr. 
ferox, Schw., and spinifer and ocellatus, LeS.; another under the name of Pelodis- 
cus for the Tr. sinensis, Wieg., and the Tr. labiatus, Bell; and a third one, for 
which Fitzinger revives the old name Amyda for the Tr. subplanus, Geoffr.^ and 
the Tr. muticus, LeS^ But all these new genera are founded upon delusive char- 
acters, as Gray has already stated, which depend only upon the progress of the 
ossification of the shield, and may be observed in specimens of different ages of 
one and the same species, as my numerous skeletons of these Turtles clearly 
show. Moreover the difference in the length of the tail is only sexual; the tail 
1 Erpet. gendr. vol. 2, p. 472 and 475, on the 
ground that Aspidonectes and Trionyx have both 
three nails to their feet. With such principles half 
the names introduced in Zoology or Botany might 
be changed. The new names proposed by Dumeril 
and Bibron for Trionyx and Aspidonectes may them- 
selves serve as an example. Now that it has become 
necessary to subdivide into distinct genera the spe- 
cies which Dumeril and Bibron refer to- Gymnopus, 
that name would be inappropriate, according to their 
own views, since all these new genera have equally 
naked feet; and the genus Cycloderma of Peters 
would render a change for Cryptopus necessary, as it 
has retractile feet, like Cryptopus. 
2 It may be said that Wagler ought to. have re- 
tained the name Trionyx for the species longest 
known; but he undoubtedly had the right to name 
as he pleased the genera he first recognized; and as 
he chose to apply that of Trionyx to the species which 
have the marginal bony plates and a broad hind lobe 
of the plastron, later writers have only introduced 
confusion in the nomenclature of this family by re- 
versing his arrangement, which, according to the law 
of priority, must in the end be adopted, in spite of 
every objection. The name Emyda, which is also 
synonymous with Cryptopus, Bum. and Bibr., appears 
for the first time in Gray's Syn. Rept., appended to 
Griffith's Transl. of Cuvier's Regn. Anim., 1831. 
3 Systematischer Entwurf einer Anordnung der 
Schildkrbten, in Annalen des Wiener Museums, 
1836, 4to. 
4 To these genera Fitzinger adds Potamochelys 
for Tr. javanicus, in his Systema Reptilium, published 
in 1843. 396 
AMERICAN TESTUDINATA. 
Part II. 
being very short in the females, and extending beyond the rim of the shield in 
the males of all the species I know. In the Catalogue of the British Museum, 
J. E. Gray restricts, in 1844, the name of Trionyx to the North American spe- 
cies; separates Trionyx indicus, Gray, as a distinct genus under the name of Chitra; 
changes Fitzinger's Amyda to Dogania, excluding however from it Tr. muticus, 
which the Austrian herpetologist associated in that genus with Tr. subplanus; and 
calls Tyrse a genus embracing Tr. gangeticus, Guv., javanicus, Geoffr., aegyptiacus, 
Geoffr., and a few other less known species; and, finally, retains the name Emyda 
for Wagler's Trionyx. To these, Dr. W. Peters1 has added a new genus from 
Mozambique, in which the absence of bony plates in the marginal rim is com- 
bined with a broad hind lobe of the plastron, and which he calls Cycloderma. 
Thus we have not less than thirteen generic names for about the same number 
of species, some of which are still very imperfectly known. 
Under these circumstances a critical revision of the genera of Trionychidae 
appears as a great desideratum in herpetology. But the materials for such a task 
seem to exist nowhere, if I judge from the published catalogues of the great muse- 
ums in Europe; and I possess myself large numbers of specimens only of the North 
American species. Yet, from their careful examination I have gathered data which 
may be of service to a future monographer of this type. Thus 1 have already 
satisfied myself that the number of our species is much greater than is generally 
supposed;2 and a careful study of their skeleton has taught me what constitutes 
generic characters in this family, so that 1 feel prepared to express an opinion 
respecting the value of the genera proposed by other writers.3 1 hold that the 
genus Trionyx, as limited by Wagler, is natural; it embraces the species described 
by Gray under the name of Emyda, and by Dumeril and Bibron under that of 
Cryptopus. Next to it stands Cycloderma, Peters, also a natural genus. The 
Indian genus Chitra, Gray, is no doubt well founded, and so also, probably, is 
Dogania, Gray, for which the name Amyda, Fitz., might have been adopted by 
Gray, as this is older. But here ends the list of genera thus far proposed which 
are at all circumscribed within natural limits, as I can show that Aspidonectes, 
Wagl., Gynmopus, Dam. and Bibr., Platypeltis, Fitz., Pelodiscus, Fitz., Potamochelys, 
Fitz., Trionyx, Gray, and Tyrse, Gray, either contain species which do not belong 
1 Monatl. Bericht der Akad. d. Wiss. in Berlin, 
1855, p. 216. 
2 Dr. Holbrook reduces the North American Tri- 
onyx to two species, and so do Dumeril and Bibron, 
and J. E. Gray. It will be seen hereafter, that the 
supposition of LeSueur respecting the species occur- 
ring in the North-western States of the American 
Union, which he considered as distinct from the 
southern species, was correct. 
8 In this connection I would remark, that it is 
hardly possible to distinguish the Trionychidae by 
their external characters, and that nothing short of a 
careful examination of the jaws, and especially of the 
skull, will reveal their generic differences. Chap. III. 
GENERA OF TRIONYCHIDSE. 
397 
to the same genus, or ought also to embrace other species, which are referred 
to different genera. Of Aspidonectes, Wagl., Gymnopus, Dum. and Bibr., and Tri- 
onyx, Gray, this will be self-evident, as soon as it is shown that the North Amer- 
ican species, which have all been referred to these genera, belong in reality to three 
different genera. Pelodiscus and Potamochelys, Fits., and Tyrse, Gray, run together 
in the same manner, on account of the heterogeneous species they contain. There- 
fore, one question only remains, Which of these names are to be retained for the 
North American species ? Of all the generic names not yet strictly applied, Aspi- 
donectes, Wagl., is the oldest; and as it was established for species, some of which, 
as Tr. javanicus and aegyptiacus, agree with some of the American ones, as Tr. 
spinifer, LeS., I shall retain that name for the genus to which our Tr. spinifer 
belongs. Next stands the genus Platypeltis, Fitz., which, though made to include 
also Tr. spinifer, LeS., is yet meant for Tr. ferox, Schw., and may therefore be 
retained for the genus of which Tr. ferox Schw. must be considered as the type, 
and which must also embrace Tr. gangeticus, Guv. The adoption of these two 
genera renders Gray's name Tyrse and Fitzinger's Potamochelys and Pelodiscus 
entirely superfluous, as Tyrse includes Tr. javanicus, aegyptiacus, and gangeticus, 
and Potamochelys Fitz, is founded upon Tr. javanicus, while Pelodiscus rests upon 
Tr. sinensis, Wiegm., and labiatus, Bell. We have thus appropriated, for six natural 
genera, six of the names introduced among the Trionychidae, and shown that six 
out of the remaining seven have no scientific value. But there is a third Amer- 
ican genus, founded upon Tr. muticus, LeS. I am glad to have an opportunity 
of honoring the memory of Schweigger by fixing upon this genus the name of 
Amyda, first proposed by Schweigger for the whole type of Trionychidae, though 
wantonly rejected by Geoffroy, and so vaguely applied by Fitzinger to one of his 
genera. 
It has already been stated that the eggs of the Trionychidae (Pl. 7, fig. 20-23) 
are spherical and very brittle.1 The young at the time of hatching (Pl. 6, fig. 
1-7) exhibit fully their family character ; they are flat, discoid, and orbicular in 
outline; their head only is comparatively shorter and rounder than in the adult, 
and the neck thicker, but the proboscis is very prominent; the feet have already 
their characteristic web, and the membranous fold which extends along the upper 
edge of the four legs (Pl. 6, fig. 2 and 5). The ossification of the shield is so 
little advanced that there is no sign of a carapace or plastron visible externally 
through the soft, scaleless skin. 
The Trionychidae were for some time supposed to have existed upon our 
globe as early as during the Devonian period. I have shown, however, that the 
1 See Part II., Chap. 2, Sect. 4, p. 334. 398 
AMERICAN TESTUDINATA. 
Part II. 
fossil remains of Caithness referred to this family are those of an extinct family 
of Fishes.1 The oldest deposits in which true Trionychidae have been observed 
are the green sands of New Jersey, according to Dr. Leidy.2 Professor Owen 
describes and illustrates very fully a number of tertiary species, which are the 
oldest he has seen.3 
I. Am yd a, Schw. (Ag.) 
The head is long, low, narrow and pointed in front, and the angle of the 
front part with the brain-box comparatively small. The nasal region is com- 
pressed sidewise, and drawn out long and narrow. The nostrils are cut in a 
peculiar way, and are not subdivided on each side by an internal ridge, as is 
the case in Aspidonectes and Platypeltis (Pl. 6, fig. 2a, 3a, 4a, and 7) ; they 
lie rather under than at the tip of the proboscis, are widely apart, broader 
below, and converge and taper upwards. The outer surface of the maxilla- 
ries curve inward under the eyes and nose, so that the mouth is small and the 
nasal region rounded. On account of the compression spoken of above, the 
sides of the mouth are concave outward from the hind to the front end, and 
that part of it which is under the nose is narrow and long. The alveolar edge 
of the upper jaw is turned down farthest at the front end, and less and less 
backward, fading out before reaching the hind end of the maxillaries; it is sharp 
in front, and toothed near the hind end; but the teeth, though quite prominent 
in the bill, are hardly perceptible in the jaw itself. The horizontal alveolar sur- 
face is narrow; it is widest near the hind end, curves down under the eye, and up 
again under the nose. There is in this genus a large opening in the skull between 
the maxillaries and the vomer. The lower jaw is also compressed sidewise and 
drawn out long and narrow under the nose, and its sides are concave outward. 
Its lower edges meet from the two sides where the compression begins, and the 
narrowed part lies at the sides of the symphysis, and the latter is carried far 
forward in rising from the lower to the upper edge of the jaw. The long, nar- 
row alveolar surface thus formed at the symphysis descends inward from the outer 
edge, slightly at the front end, more and more backward, and from the symphy- 
sis to the angle of the jaw that surface is very narrow and almost vertical. 
The alveolar edges are sharp all round. Thus we have in this genus a small 
1 See Part IL, Chap. 1, Sect. 17, p. 303. 
2 Proc. Ac. Nat. Sc. Phil. vol. 5, 1851, p. 329, 
and vol. 8, 1856, p. 73. 
8 R. Owen and T. Bell, Fossil Reptilia of the 
London Clay, in Trans, of the Palaeont. Society, 
London, 1849, p. 46. Chap. HI. 
GENERA OF TRIONYCHID2E. 
399 
mouth with a sharp bill, and with two long surfaces under the nose, which are 
brought close together when the mouth is shut. The food found in the stomach 
of a specimen of Amyda mutica, examined in a fresh state, consisted of larvae of 
Nevropterous insects. 
The type of the genus Amyda is LeSueur's Trionyx muticus. It is thus far 
the only species known to belong to this genus, unless Trionyx euphraticus, Geoffr., 
be generically identical with it, which I have no means of ascertaining. 
Amyda mutica, Fitz. The description of this species by LeSueur is the fullest 
and most accurate.1 He has distinctly pointed out its most prominent specific 
peculiarities: the depression along the middle line of the back, instead of an obtuse 
keel, the total absence of spines along the anterior margin of the carapace and 
of tubercles upon the back, and the peculiar coloration of the lower surface, which 
is whitish, without spots or mottled marks, as occur under the neck and upon the 
lower surface of the feet of Tr. spinifer, with which it has often been confounded. 
LeSueur also mentions the long, narrow, and pointed jaws, which constitute one 
of its generic peculiarities. The form of the nostrils, first noticed by Dr. Hol- 
brook, is also generic. 
I have seen more than twenty specimens of both sexes, in every stage of 
growth. The males have always a longer tail than the females, extending 
beyond the margin of the disc, while it is concealed under it, in the other sex. 
The young, (Pl. 6, fig. 6 and 7,) at the time of hatching, and for some time 
afterwards, are entirely white below, even under the neck and upon the lower 
surface of the feet; the latter, however, becomes bluish gray with age, but it 
is never spotted or mottled. Upon the sides of the head, from the eyes back- 
wards, runs a narrow white band bordered by black lines, which is merged behind 
in the white surface of the lower side of the neck, but extends forwards across 
the eye to the tip of the proboscis. This band disappears more or less in old 
specimens. In very young specimens, the back has slight black spots upon an 
olive colored ground, and exhibits, along the hind margin and the sides of the 
carapace, a broad yellowish band circumscribed by a black line. With advancing 
age the marginal band disappears, and the dark marks upon the back spread 
until they vanish entirely, and the ground becomes itself darker and more gray- 
1 In Mem. Mus. Hist. Nat Paris, 1827, vol. 15, 
p. 263, Pl. 7. It has since been described by Major 
LeConte, (Lye. Nat. Hist. New York, vol. 3, p. 95,) 
and by Dr. Holbrook, (N. Amer. Herp. vol. 2, p. 19, 
Pl. 2.) J. E. Gray considers it and Tr. ferox as 
being the only genuine representatives of the genus 
Trionyx, as he would limit it. DeKay (Zool. of New 
York, vol. 3, p. 7, PL 6, fig. 11) represents it as the 
young of Tr. ferox, though he considered it at first 
as a distinct species, for which he had proposed the 
name of Tr. ocellatus. His figure leaves no doubt 
that he had a specimen of Tr. muticus before him. 
Wagler refers it to his genus Aspidonectes, and Du- 
meril and Bibron to their genus Gymnopus. 400 
AMERICAN TESTUDINATA. 
Part II. 
ish brown. The largest specimen I have seen measured twelve inches from the 
front to the hind margin of the carapace, and ten inches across. 
This species, which is the smallest of the North American Trionychidm, extends 
from the States of New York and Pennsylvania westwardly to the tributaries of 
the Missouri, and the upper and middle Mississippi. I have never seen specimens 
from the lower course of the Mississippi, nor from the Southern and South-east- 
ern States. It is common in Lakes Erie and Ontario, (Maj. LeConte;) in Ohio, (Dr. 
Kirkland,) and in Indiana, (LeSueur.) Through the kindness of Prof. Rich. Owen 1 
have obtained specimens from the very locality from which LeSueur described his. 
Dr. J. Rauch has sent me specimens from Iowa, Mr. G. Stolley from the Osage 
River in Missouri, and Prof. Sp. Baird from the Alleghany River in Pennsylvania. 
The eggs are smaller than those of the other species of this family which I know. 
They are represented (Pl. 7, fig. 21) from specimens sent me by Dr. J. Rauch 
of Burlington, Iowa, and by Mr. Franklin Hill of Delphi, Indiana. 
II. Platypeltis, Fitz. 
The head is short, broad, and high ; its front part is turned down steeply, 
and makes a sharp angle with the brain-box. The sides of this part approach 
each other gradually to the base of the proboscis, which is straight. The nos- 
trils are terminal, and nearer together than in Amyda, crescent shaped in form 
and vertical in position; they are subdivided by a horizontal ridge, projecting on 
each side of the median partition, which is wider than in Aspidonectes. The outer 
surface of the maxillaries slants far outward from the suture with the prefrontals 
down to the alveolar edge, thus making the mouth very broad. The alveolar 
edge is blunt, except at the front end; it is turned down but little at the sides, 
and flares out so much there that in the adult there is but little distinction 
between the vertical and horizontal alveolar surfaces, and both together form one 
very broad surface adapted to crushing; but, at the front end, this surface is nar- 
row and nearly vertical. There is here, as in Amyda and Aspidonectes, a large 
opening in the skull between the intermaxillaries and the end of the vomer. 
The lower jaw, like the upper, has a very broad alveolar surface, which also 
continues broad back to the hind end of the maxillaries, projecting near that end 
far over both the outer and inner surfaces of the jaw below, and reaching inward 
farther even than its lower edge. This surface is nearly flat at the symphysis, 
but it has a deep depression near the hind end. In this genus, then, the mouth 
is large, but short; the jaws are strong, and the alveolar surfaces broad and blunt, 
and well fitted to crush. The shells of a Paludina and fragments of Anodontas Chap. III. 
GENERA OF TRION YCHIDJE. 
401 
were found in large quantities in the stomach of a specimen of Trionyx ferox, the 
type of the genus, examined shortly after it had been caught. Similar fragments 
were found in the faeces of other specimens preserved alive. 
The type of the genus Platypeltis is the Tr. ferox, Schw. It is the oldest 
species of this family known from North America. It was first described by Dr. 
Garden of Charleston, in a paper printed in the Philosophical Transactions of 
the Royal Society of London, in 1771, from which all later writers have bor- 
rowed their information, until Major LeConte, Dumeril and Bibron, and Dr. Hol- 
brook1 gave a fuller account of this species. I have little to add to their descrip- 
tions ; but these authors are certainly all mistaken in considering this species 
as identical with LeSueur's Tr. spinifer. Not only are Tr. ferox, Schw., and Tr. 
spinifer, LeS., distinct species, but they belong unquestionably to different genera, 
as a comparison of the skulls will show at first sight. I have compared large 
series of specimens of both kinds, from the very young to adults, and can speak 
with confidence upon this point. Though Fitzinger unites also Tr. spinifer and 
ferox as synonymes, I have thought it preferable to adopt' the name he proposes 
for this genus, and assign to it a definite meaning, than to frame a new one, 
which in the end would appear co-extensive with Platypeltis. 
Platypeltis ferox, Fitz.2 This species is only found in the Southern States, 
from Georgia to Western Louisiana. Dr. W. B. Daniel has sent me many speci- 
mens from Savannah, its northernmost station in the Atlantic States. It abounds 
in the St. John River of Florida (Bartram, LeConte). I am indebted for many 
specimens from Western Georgia and Western Florida to Dr. Gessner, of Colum- 
bus, and Mr. Eppes, of Tallahassee. Dr. Nott has sent me others from Alabama, 
especially a series of very young ones. To Professor Chilton, of New Orleans, 
I am indebted for specimens from the Lower Mississippi; and to Mr. Winthrop 
Sargent, of Natchez, for the largest specimens I have ever seen or heard of, one 
of which measured eighteen inches and a half from the front to the hind mar- 
gin of the carapace, and sixteen across. 
1 Compare the works q. a., p. 30, for further ref- 
erences, but exclude from their synonymy every thing 
that relates to Tr. spinifer, LeS. 
2 The names most frequently applied to this spe- 
cies, by different authors, are Testudo ferox, Trionyx 
ferox, Tr. carinatus, Tr. georgicus, Tr. Brongniarti, 
Tr. Bartrami, Tr. Harlani, Aspidonectes ferox, Asp. 
carinatus, and Gymnopus spiniferus. The external re- 
semblance between Platypeltis ferox and Aspidonectes 
spinifer and asper, is so great, that I am not sur- 
prised that they have been confounded, or even delib- 
erately considered as identical. We have, in fact, a 
case here, of which a few other examples only are thus 
far known, in which, under the most surprising simi- 
larity of external appearance, marked structural pecul- 
iarities, amounting to generic differences, are hidden. 
I have already pointed out such cases in the genera 
Phoxinus and Chrosomus, and in the genera Carpi- 
odes, Bubalichthys, and Ichtbyobus, among Cypri- 
noids (Amer. Journ. of Sci. and Arts, 2d der. vol. 19, 402 
AMERICAN TESTUDINATA. 
Part II. 
It is true that this species very much resembles Tr. spinifer, LeS., in its 
external appearance; but, even without referring to their generic characters, they 
may readily be distinguished in every stage of growth. The male of Platypeltis 
ferox, with its projecting tail, is much more oblong1 than that of Aspidonectes 
spinifer, while the females are very similar in their rotundity. The tubercles 
upon the shield are also larger and more numerous in the male ferox than in 
the female; just the reverse from what we see in spinifer. The young ferox 
(Pl. 6, fig. 3) has two or three concentric black lines separating the pale margin 
from the light brown colored back, which are sometimes preserved even to their 
full-grown size ; in Asp. spinifer I have never observed more than one such 
line, which disappears rather early. The back of Pl. ferox is studded with well- 
defined black dots, which become ocellated only in later years, and are finally 
changed into dark blotches in the adult. The lower surface is entirely white, 
even the lower surface of the feet, which are mottled, streaked, and dotted with 
black in Aspidonectes spinifer, Asp. nuchalis, and Asp. asper. Aspidonectes spinifer 
never grows so large as ferox, and is only found in the Northern States, within 
the same limits as Amyda mutica, with which it is mostly found associated. The 
eggs of Platypeltis ferox (Pl. 7, fig. 22) are of a somewhat smaller size than those 
of Aspidonectes spinifer: they are, however, a little larger than those of Amyda 
mutica, represented upon the same plate. 
The peculiar coloration of the Lower surface of the feet, and the mottled 
appearance of the lower part of the neck, of Asp. spinifer, first attracted my 
attention as differing from Platypeltis ferox, and led me to a careful revision of 
our Trionychidse. Trusting to the accuracy of previous writers, I have myself 
believed, for a number of years, that there existed only two species of that 
family in the United States, and that these two species belonged to one and the 
same genus, until large collections of specimens from every part of the country, 
and a thorough examination of their structure, satisfied me that we possess not 
less than six species, belonging to three different genera: one Amyda, one Pla- 
typeltis, and four Aspidonectes, the geographical distribution of which is particu- 
larly interesting. In the North-Western States, two species occur together, belong- 
ing to two different genera, Amyda mutica and Aspidonectes spinifer; in the 
Middle Western States one species, Aspidonectes nuchalis; in the South-Eastern 
p. 71.) Many similar examples might be quoted 
among the Rodentia. 
1 The figure of Dr. Holbrook, in the North Amer- 
ican Herpetology, Vol. 2, Pl. 1, represents very dis- 
tinctly this oblong form of the male Platypeltis ferox. 
It is less so in Aspidonectes spinifer, as the figure of 
LeSueur published in the Mem. du Mus., Vol. 15, Pl. 
G, distinctly shows. These two figures will at once 
exhibit the differences characteristic of the forms of 
the two species. Chap. HI. 
GENERA OF TRIONYCIIID^. 
403 
and Southern States, two species, belonging to two different genera, Platypeltis 
ferox and Aspidonectes asper; and in the South-West, in Texas, one species, Aspi- 
donectes Emoryi. 
III. Aspidonectes, Wagl. 
The head is broader, and less flattened, than in Amyda. The sides of the 
front part of the head approach each other continually, and are nearly straight 
from behind forward. The proboscis is straight, and cut vertically; the nostrils 
are crescent-shaped, and subdivided by a projecting ridge arising from the middle 
of the narrow vertical partition which separates them. The outer surface of the 
maxillaries curves out, from the suture with the prefrontals, for about half its 
width, then turns down and descends almost vertically to the alveolar edge. Thus 
the mouth is broader, and the nose less rounded, than in Amyda. The alveolar 
edge curves down slightly from end to end; it is sharp, but in the adult it has 
no teeth. The vertical alveolar surface is broadest near the front end, and nar- 
rows thence backward. The horizontal alveolar surface is broadest at the hind 
end, and narrows thence forward; it descends nearly constantly from the hind to 
the front end. There is here, as in Amyda, a large opening in the skull in 
front of the vomer. The symphysis of the lower jaw is much shorter than in 
Amyda, and the end of the jaw broader. The alveolar surface narrows from the 
symphysis backward; at its front end it descends steeply from the outer edge 
inward, but at its hind end the inner edge is raised, so that there is a slight 
depression in the surface there. The alveolar edge is sharp all round. Thus 
we have in this genus stronger jaws, with broader alveolar surfaces, than in 
Amyda, and cutting, but not toothed, alveolar edges. 
Aspidonectes spinifer, Ag. All modern herpetologists seem to agree in the 
opinion that Trionyx spinifer, LeS., is identical with Tr. ferox, Schw. I have 
satisfied myself, by a direct comparison of a large number of specimens of every 
age, that this is a mistake. It is true, Dr. Holbrook has shown1 that there is 
an easy water communication between the different stations occupied by these 
Turtles; but it does not follow, that, because animals may migrate without serious 
obstacle over any extent of land or sea, they are necessarily the same within 
the boundaries of such areas. The ingenious suggestion of Dr. Holbrook, intended 
to explain the presence of a southern species in the waters of the North-Western 
and North-Eastern States, as far as Lake Champlain, has in reality only put an 
end to all further comparisons between our Trionychidae. 
1 North American Herpet. Vol. 2, p. 15. 404 
AMERICAN TESTUDINATA. 
Part II. 
The only correct description I know of Aspidonectes spinifer is that of Le- 
Sueur.1 All later writers have confounded it more or less with Platypeltis ferox, 
until the two were finally considered as identical. Its chief specific characteristics 
are not the spines along its anterior margin, whence the name is derived, - for 
such spines exist more or less in all species of the genus Aspidonectes, - but the 
blunt keel, which extends along the median line and slopes uniformly upon the 
sides, a character by which it is easily distinguished from Aspidonectes nuchalis, 
a species thus far overlooked, in which there is a marked depression on either 
side of a similar keel along the median line. When young, Aspidonectes spinifer 
(PL 6, fig. 1 and 2) is dotted all over the back with small ocellated spots, which 
increase with age, and then fade into irregular blotches upon a darker or lighter 
yellowish brown ground. In early age, the margin has a narrow, light-colored 
seam, separated from the darker disc by a black line, which fades and disappears 
with age. The front part of the neck is mottled with yellow and black, and 
so, also, is the lower surface of the feet. Besides the difference in the length 
of the tail, the male differs from the female by a slightly oval form. The 
spines along the front margin, and the tubercles which rise behind them and 
upon the hind part of the carapace, are less prominent in the males than in 
the females, exactly the reverse from Platypeltis ferox. The largest specimen I 
have seen, measured fourteen inches from end to end of the carapace. The eggs, 
(Pl- 7, fig. 23,) for which I am indebted to Dr. Bauch and Mr. Franklin Hill, 
are a little larger than those of Platypeltis ferox. Major LeConte questions 
the propriety of the name ferox for the southern Trionyx, as he says they are 
not more inclined to bite than most other species of Testudinata; but LeSueur 
reports that he was severely bitten by Tr. spinifer, and I have myself experienced 
the power of its jaws. This apparent contradiction, as long as ferox and spinifer 
were considered as the same species, may be owing to the generic differences of 
these Turtles. Aspidonectes spinifer is common from Lake Champlain and the 
western parts of the States of New York and Pennsylvania, through Ohio, Indi- 
ana, Illinois, Missouri, Michigan, Wisconsin, and Iowa, to the head waters of the 
Mississippi and Missouri, even to the very foot of the Rocky Mountains (Lewis 
and Clark). It inhabits most of the tributaries of the Mississippi within the 
State of Wisconsin (Dr. P. R. Hoy). 1 have received specimens from Lake 
Champlain, through the kindness of the late Rev. Zadd. Thompson; and from the 
1 In the Memoires du Museum d'Histoire natu- 
relie, Vol. 15, p. 258, Pl. 6, under the name of Trio- 
nyx spiniferus, which ought, however, to be written 
spinifer. LeSueur describes as a variety of this species, 
under the name of Trionyx ocellatus, what was, no 
doubt, a young female. Wagler considers this species 
as synonymous with Platypeltis ferox. DeKay's Tri- 
onyx ocellatus is Amyda mutica. Chap. HI. 
GENERA OF TRION YCIIIDzE. 
405 
Alleghany River, in Western Pennsylvania, from Professor Baird. It was not 
known in the State of New York before the completion of the Erie Canal; but 
since, it has been caught in the Mohawk and in the Hudson Rivers, near Albany 
(DeKay). Professor Rich. Owen has sent me some from the Wabash, near New 
Harmony, in which place LeSueur first observed this species. It is abundant 
in Lakes Ontario and Erie, in the streams that flow into these lakes, (Say and 
LeConte,) and in all the streams of Ohio (Kirtland). I am indebted for speci- 
mens from the Ohio to Mr. Jos. Clarke, of Cincinnati; from Northern Indiana to 
Mr. Franklin Hill, of Delphi; from Michigan, to Dr. A. Sager and Professor 
Alex. Winchell, of Ann-Arbor; from Illinois, to Mr. J. H. McChesney; from 
Iowa, to Dr. J. Rauch; from the Osage River, in Missouri, to Mr. G. Stolley; 
and from Fort Union, on the Upper Missouri, to the Smithsonian Institution. 
It is frequently found in the smaller streams that discharge into the Missouri 
(Say). The occurrence of this species so far north contrasts strangely with the 
opinion, prevailing among herpetologists, that the representatives of this family 
are inhabitants of the large rivers of the tropics.1 
Aspidonectes asper, Ag. I have for a long time known only an imperfect 
skeleton of this species, belonging to the Smithsonian Institution, and prepared 
from a specimen forwarded by Professor B. L. C. Wailes, of Washington, Missis- 
sippi. Afterwards I obtained, through the agency of Dr. L. Harper, a stuffed 
specimen belonging to the Museum of the University of Oxford,2 that had been 
collected during the geological survey of Mississippi, under the superintendence 
of Professor Wailes. Lately I have received a number of living specimens, 
through the kindness of Mr. Winthrop Sargent of Natchez, which confirm the 
opinion I had formed, from the scanty materials at first at my command, that 
there exists, in the South-Western States, a distinct species of Aspidonectes, which 
might easily be mistaken for Asp. spinifer, and even be confounded with Platy- 
peltis ferox.3 
Aspidonectes asper is at once distinguished from all the other species of this 
1 Comp. Dum. and Bibr. Erpet gener. Vol. 2, p. 
449, where it is stated that all the species, the origin 
of which is known, inhabit the rivers and lakes of the 
warmest parts of the globe, among which, it is true, 
they mention the Ohio. 
2 Upon application of Dr. Harper, the trustees of 
the University at Oxford very liberally consented to 
forward to me for examination all the specimens of 
Testudinata collected during the geological survey of 
the State of Mississippi. These specimens have been 
of very great importance to me in fixing the geo- 
graphical range of many species, which before were 
not known to occur in the lower course of the Mis- 
sissippi. 
8 I have no doubt that such a confusion generally 
prevails, as no zoologist has thus far alluded to the 
presence of two representatives of this family in the 
Southern States, and the very specimen of the Mu- 
seum of Oxford, alluded to above, bears the name of 
Trionyx ferox. 406 
AMERICAN TESTUDINATA. 
Part IL 
genus, and also from Platypeltis ferox, by the very coarse and large tubercles 
of the front and hind part of the carapace, which extend, behind, even over 
the bony shield, and are there supported by prominent warts of the bony plates. 
These bony warts exist in no other species with which I am acquainted: their 
form is very irregular, sometimes oblong and sometimes orbicular; they also project 
more or less. Another marked peculiarity of this species consists in the greater 
bluntness of the extremities of the jaws, which are more rounded than in Asp. 
spinifer. The jugal arch is also broader. The difference between the males and 
the females is more striking in this species than in any other, the males being 
regularly oval, whilst the females are almost circular in their outline. I have 
noticed no difference between the coloration of this species and that of Asp. 
spinifer, except that in younger specimens of Asp. asper there are, as in Platy- 
peltis ferox, two or three black lines separating the pale rim of the posterior 
margin, whilst there is only one in Asp. spinifer; these lines are, however, closer 
together, and fade away sooner than in Platypeltis ferox. This combination of 
external characters, partly resembling Asp. spinifer and partly Plat, ferox, explains 
how these species could be mistaken as one. Indeed, were it not for their 
generic characters, a series of specimens might easily be selected, showing every 
possible transition between them. I do not know, in the whole animal kingdom, 
another type, in which the importance of the study of the generic characters, 
prior to distinguishing species, is brought more forcibly before the student, than 
the family of Trionychidae, unless it be that of Cinosternoidm. 
Thus far I have had no opportunity of examining the eggs of this species; nor 
do I know the appearance of the young, recently hatched, unless a young speci- 
men, sent me by Professor Baird from the north-western part of Louisiana, be 
the young of this species. It differs but slightly from the young Aspidonectes 
nuchalis; it has the same large ocelli, but the bridge connecting the carapace 
and plastron, and a longitudinal area, before and behind the bridge, are tinged 
with black. 
Aspidonectes nuchalis, Ag. I have only seen three adult specimens of this 
species, for which I am indebted to Prof. Lindsley, of Nashville, Tennessee, and 
a number of young ones, which I owe to the kindness of Prof. Baird; the first 
collected in Cumberland River, the others in the head waters of the Tennessee 
River. I learn from Dr. Samuel Cunningham, of Jonesboro', that, in the higher 
tributaries of the Tennessee River, a species of Trionyx, which I suppose to be 
this, is found at a considerable height in the Alleghanies; a very unexpected fact, 
considering the prevalence of this family in warmer regions. This species differs 
strikingly from Asp. spinifer in the much more elongated form of the male, and 
in the great development of the marginal spines and of the tubercles upon the car- Chap. III. 
GENERzY OF T RIONYCIIIDfE. 
407 
apace, which project very slightly in the male Asp. spinifer. The young differ also 
in having, at birth, comparatively large ocelli upon the carapace, which fade into 
large blotches in the adult. But the most prominent specific character consists 
in the marked depressions on either side of the blunt median keel, and also in 
the triangular dilation of that keel behind the front margin of the carapace. The 
lower surface of the neck and feet is mottled and speckled, as in Asp. spinifer. 
From this scanty information it may be inferred that Asp. nuchalis ranges over 
the tracks bounded in the south by the distribution of Platypeltis ferox, and in 
the north by Amyda mutica and Aspidonectes spinifer. I have received the speci- 
mens mentioned above too late to cause any of them to be represented upon 
my plates. 
Aspidonectes Emoryi, Ag. The first intimation I had of the existence of another 
species of Aspidonectes within the boundaries of the United States was from the 
sight of two eggs collected in Texas by Dr. Heerman, and presented by him to 
Dr. Holbrook, who gave them to me. These eggs (represented in PL 7, fig. 20) 
were so much larger than those of either of the three other species of the family 
which I then knew, that I did not hesitate to consider them as derived from an 
unknown species. My supposition was very soon changed into certainty, after I 
had received from the Smithsonian Institution all the specimens of Turtles col- 
lected in Texas during the operations of the Boundary Survey, under the com- 
mand of Col. Emory, among which were young and adult specimens of this spe- 
cies, collected in the lower Rio Grande of Texas, near Brownsville. I take great 
pleasure, therefore, in dedicating this species to that distinguished officer. I 
afterwards received some more young specimens from Mr. G. Stolley, collected in 
Williamson County, Texas, in a stream emptying into the Rio Brazos. 
This species is very readily distinguished from the two preceding by the absence 
of prominent spines along the front margin of the carapace, where a single row 
of small tubercles is visible, and by the greater width of the hind half of the 
shield, the upper surface of which is dotted all over with small whitish tubercles, 
like grains of sand, arranged in longitudinal rows along the posterior part of the 
vertebral column, and diverging somewhat upon the sides, upon a uniform greyish 
ground, without ocelli or blotches. These tubercles are somewhat larger in adult 
specimens than in the young. The pale rim of the hind margin is much broader 
than in any other species of the family. In young specimens, (PL 6, fig. 4,) that 
rim is separated by a distinct black line, which afterwards fades; the white tuber- 
cles are also encircled by faint black lines, which soon disappear. The whole lower 
surface is white, except dark lines along the inner surface of the fingers. The 
upper surface of the legs and the upper part of the neck and of the head are 
marked with small black dots. A white line extends behind the eyes, and fades 408 
AMERICAN TESTUDINATA. 
Part II. 
into the white sides of the neck. A straight black line extends in front of the 
eyes across the space which separates them, and forms a triangle with two sim- 
ilar lines extending from each eye to the tip of the proboscis. The largest speci- 
men I have seen, measured twelve inches from end to end of the carapace, and 
nine and a half across the middle. All the specimens I have examined thus far 
were obtained in Texas. Rev. Edward Fontaine, of Austin, Texas, writes me 
that it delights in clear, bold, and rocky streams, and possesses nothing of the 
sluggishness of other Testudinata, but is brisk and vivacious in all its movements, 
running rapidly on land when dropped from the hook of the angler, and swim- 
ming with great velocity. 
I expect to be gravely criticized for describing the species of our Trionychidm 
in the manner in which it has been done in the preceding pages. Seeming dis- 
crepancies may, indeed, be noticed between the generic and specific characters of 
these Turtles as expressed here, and the description of the family characters as 
presented in a former section. But Animal Morphology has still more 'striking 
contradictions in store in its nomenclature, than those of which I may have been 
thus far guilty. So long as our language has not yielded to the necessities of the 
case, there will be something awkward in the use of expressions that are famil- 
iarly employed to designate definite forms, when transferred, with qualifications, 
to animal forms, which have neither the definiteness nor the regularity of mathe- 
matical figures. It may appear absurd to speak of a flattened sphere, of an 
elongated circle, (not an ellipse,) and the like ; but I hold that it is better to 
make such a use of these words than to avoid apparent contradictions by the 
introduction of circumlocutions; for such expressions are at once characteristic, and 
may become quite picturesque when judiciously applied. The family of Naiades 
among Acephala has afforded me a welcome opportunity to test the importance 
of form, as the leading character of families. There is scarcely another natural 
group which embraces species apparently more diversified in their forms than 
these shells. We need only compare Unio stegarius with U. rectus or Shepardi- 
anus, or U. alatus with U. . cylindricus, or with U. Cardium or U. torsus or U. 
mytiloides, triqueter, flexuosus, etc. Every possible form seems to be represented 
in that family, from the quadrangular or triangular to the spherical. And yet 
all Naiades have one and the same typical form, determined by their internal 
structure, which may be described as ovate, with a double flexure on the lower 
side, towards the hind extremity; and this form is determined by the structure of 
the mantle.1 Unio flexuosus exhibits this typical form in its most distinct out- 
1 I shall have an opportunity to illustrate these 
statements most fully in a future volume, probably 
the fifth, which is to be devoted exclusively to the 
history of our fresh-water Mussels. Chap. III. 
GENERA OF CHELYDROIDS. 
409 
lines, but so far exaggerated as to appear one of the most aberrant representa- 
tives of the whole family ; whilst it is so subdued in the most common species 
as hardly to be perceptible. This being the case, I feel justified in saying, that, 
whosoever does not see that all Naiades have the same form, is still as far 
behind in Animal Morphology as the tyro in Geometry, who could not understand 
that the circle may belong to a series of which the straight line would be an 
extreme case, and again form another series with the ellipse, the parabola, and 
the hyperbola; with this fundamental difference only, that all these forms belong 
to an unstable equilibrium in the organic world, whilst they have fixed relations 
in the inorganic. 
SECTION VI. 
THE GENERA OF CHELYDR0ID2E. 
I know only three genera belonging to this family, and am not aware that 
there exist others even remotely allied to them. These are the genus Chelydra, 
Schw., the genus Platysternum, Gray, and the genus Gypochelys, characterized in 
this work for the first time. The genus Chelydra was characterized by Schweigger1 
in 1812; Fleming2 called it Chelonura in 1822; Latreille3 called it Saurochelys in 
1825; in the same year J. E. Gray4 gave it the name of Rapara; and in 1835, 
Dumeril and Bibron,5 overlooking the many names already proposed by their 
predecessors, insisted upon giving it another new one, Emysaurus, which they spell 
also Emysaura, and which has occasionally been further quoted under the form 
of Emydosaura.6 The genus Platysternum was first characterized by J. E. Gray7 
in 1831. Though I never had an opportunity myself of examining this last genus, 
I have no doubt that it belongs to the family of Chelydroids; and the descriptions 
and figures given by Gray, and Dumeril and Bibron,8 furnish satisfactory evidence 
of its true relations. This being the case, it is interesting to notice how widely 
apart from one another the few living representatives of this family are found 
upon the surface of our globe. Platysternum with one species, in China; and Che- 
lydra and Gypochelys, each with one species, in North America, But this singular 
geographical distribution acquires a special interest when it is further stated, that 
the American genera Chelydra and Gypochelys are only met with on the east- 
1 In the work q. a., p. 394, note 5. 
2 In his Phil. Zool., vol. 2, p. 270. 
8 Families naturelles du Regn. An. 
4 Ann. of Phil., 1825, vol. 10, p. 210. 
5 Erp. gen., vol. 2, p. 199, and 318. 
6 Cat. Brit. Mus., 1844, p. 34. 
7 Proc. Zool. Soc., London, 1831, p. 106. 
8 Erp. gen. Pl. 16, fig. 2. 410 
AMERICAN TESTUDINATA. 
Part II. 
ern side of the American continent, and not at all to the west of the Rocky 
Mountains, or even in their immediate vicinity; since we cannot fail to see, in 
this apparently anomalous distribution, another instance of the remarkable similarity, 
pointed out by the founder of the Physical Geography, between the eastern or west- 
ern shores of our continents when respectively compared with one another, in their 
physical features, and in the character of their inhabitants. 
There is another fact of general interest connected with this family, - its exist- 
ence in Europe, in past geological ages, while no trace of these Turtles can be 
found there now. The fact is well authenticated : two very distinct species of 
Chelydroids, from the Miocene beds of Oeningen, near the Lake of Constance, have 
been described and handsomely illustrated by Th. Bell1 and Herm, von Meyer.2 But 
what is the meaning of such a phenomenon ? I am inclined to think that the 
early introduction of this family, in Europe, during the Tertiary period, became an 
inducement for their reproduction, in a later age, upon other continents, one 
of which, at least, bears every characteristic of having been, long before Europe, 
and for ages past, essentially what it is now, as far as its physical features are 
concerned. I would, therefore, suggest that America has among its Testudinata 
old-fashioned types, because it is the oldest continent, and not because Chelydra 
is any more characteristic of the American fauna than of the European. 1 shall 
presently call attention again to this point. 
The eggs of the Chelydroida), like those of the Trionychidm and Chelonii, are 
spherical ; but they are liable to occasional variations, those of Chelydra serpen- 
tina at least, for I have twice obtained ovate eggs from their nests, and once 
found an ovate one in its ovary (Pl. 7, fig. 25). Among the spherical ones 
(fig. 24 and 26) there is also some variation as to size, and to a less extent 
respecting the hardness of the shell. I have no reason to infer from these 
facts that the eggs of Testudinata are generally liable to great variations, because 
the family of the Chelydroidm stands, as it were, between the lower families with 
spherical eggs and the higher families with ovate eggs, and we should expect 
a stronger tendency to unusual combinations in animals holding such a position 
than in others; though it must not be forgotten that there is also some dispo- 
sition to vary among the eggs of the families in which they are oval, and that 
the highest Testudinata lay spherical eggs like the lowest. This last fact seems 
to me strongly to vindicate the view which I have already expressed, that the 
Testudinina are not absolutely higher than the other natural groups of this type, 
and cannot, therefore, be considered in the light of a sub-order coequal with the 
Chelonii proper. (Compare p. 249.) 
1 Proc. Geol. Soc., London, 1831. 
2 Zur Fauna der Vorwelt, 1 vol. fol. Chap. III. 
GENERA OF CHELYDROIDS. 
411 
The young of the family of Chelydroidse exhibit new features, different from 
those which we have noticed before in sea Turtles, in Emydoidae, and in Trio- 
nychidm. When hatched, they start, like the Trionychidm and Emydoidae, with a 
circular body; but their body is relatively much higher than that of the Trio- 
nychidae and Emydoidae, and flattens out with age. The circular form grows 
first more and more oval, then oblong, in Gypochelys, (Pl. 6, fig. 23-27,) by a 
straightening of the lateral margin; while in Chelydra (Pl. 4, fig. 13-16, and Pl. 
5, fig. 18 and 19) an oval circumference is permanent throughout life. The orna- 
mental bass-relief which appears upon the surface is not less peculiar in Chelydroidae. 
In Gypochelys it exists all over the body; in Chelydra particularly on the upper 
shield, where the corium rises in the form of larger and smaller warts and ridges. 
Besides smaller warts, which are spread irregularly all over the body in Gypo- 
chelys, and over the shield in Chelydra, we see in both genera three rows of lon- 
gitudinal ridges formed by the median and the two costal plates of the back. These 
ridges are homologous to the three longitudinal rows of the young Thalassochelys 
and of the genus Chelys. The homology of Gypochelys with the latter genus is 
even carried so far, that, in the adults, the horny plates as well as the corre- 
sponding bony shields, when only seen from above, could hardly be distinguished. 
Even that curious twisting, characteristic of the lateral ridges, is the same in both 
cases, and the sutures between the costal plates run through them in exactly the 
same places. We see here a homology of forms connected with the greatest dis- 
crepancy of structure ; for the true skeleton of Chelys, taken as a whole, is so 
different from that of the Chelydroidm, as to justify fully their separation as dis- 
tinct families.1 Beyond these three ridges, we find, in the young Gypochelys, two 
more ridges on the top of the marginal plates. These are wanting in the young 
and in the adult Chelydra, and nearly so in the adult Gypochelys. Moreover, 
in the adult Chelydra, the three median ridges fade also more and more with 
advancing age, and we have seen large adult specimens which were entirely smooth. 
The lateral and posterior marginal plates of the young of this family are narrower 
outwardly than where they are attached to the costal plates.' This causes the 
circumference of the posterior half of the trunk to appear deeply scalloped in 
Gypochelys, but less so in Chelydra, where these indentations disappear more and 
more with advancing age. At the first sight, the tail would seem, on account 
of its great size, to be an organ adapted for similar functions as in young Emy- 
doids, in which we found it also relatively very long; but upon closer examina- 
tion we may soon be satisfied that the round, strong tail of the Chelydroids, 
though very long, is not a rudder as in young Emydoids, but a support in walk- 
1 See the family characters of Chelydroicke and Chelyoids, p. 335-346. 412 
AMERICAN TESTUDINATA. 
Part II. 
ing, or in attacking their prey and in defending themselves. The Chelydroids make 
the same use of their tail when adult. The long tail of the young is there- 
fore typical here, and not an embryonic feature, as it is in the Emydoids. The 
Chelydroidae are mud Turtles; they walk on the mud, or on the bottom of the 
water, and, when put into the water, they instantly dive to the bottom. Nevertheless, 
in this family, the feet are also better adapted for swimming in the early part of 
life than later; at least, the web between the toes is thinner, and thus the toes 
more movable than in the adult. This is particularly obvious when comparing the 
hind feet of the young Gypochelys with those of the adult; for in the latter they 
are heavy, bulky, plantigrade, walking feet. 
Most of the characters which we have considered thus far are common to 
the two American genera of Chelydroidae, Chelydra and Gypochelys. But there 
are already features, in the young of the first year, which constitute generic 
differences. This is particularly evident in the head and tail. The head of 
the young Gypochelys exhibits already fully that wedge-shaped eagle bill, running 
sharply down in front, by which it is so clearly distinguished from Chelydra when 
adult; while, in the young Chelydra, the head is already much shorter, and the 
jaws more rounded. Again, the tail distinguishes them also when young most 
strikingly ; its lower surface, in Gypochelys, being covered with many small 
more or less imbricated scales, just as in the Anguiformes among Lizards, while 
in Chelydra, as in most Snakes, there run all along the under surface of the 
tail, two rows of large scales. In Lizards and in Snakes, this amounts to a 
family character, the scales of the tail being there of more importance than in 
Turtles, in which we can only recognize generic differences in their peculiarities. 
The American members of this family are divided into two strongly marked 
groups, one comprising the genus Gypochelys, the other the genus Chelydra. 
These groups have clearly defined generic characters; but it is a question, whether 
some of their distinguishing characters have not a more than generic value. The 
elements of form are in general the same in both; but there are wide differences 
in the forms of the head, which are, perhaps, such as to make each group a 
sub-family.1 In Gypochelys every thing about the head is fitted to give the 
1 Whether the family of Chelydroids contains two 
sub-families or not, there can be no doubt that its 
North American representatives belong to two dis- 
tinct genera. It will be easier to settle the question 
of the sub-families after an opportunity has been had 
to compare carefully the genus Platysternum. It 
may seem immaterial to ascertain this point, when 
it is considered that the whole family numbers only 
three genera. But, if the principles which I have ad- 
vocated in the first part of this work are correct, it 
will be found that Platysternum will either be inter- 
mediate between Chelydra and Gypochelys, in which 
case the family would not be subdivided, or Pla- 
tysternum will lean more towards one or the other 
of the American genera, in which case it would at 
once appear that it embraces tw'o distinct sub-families. Chap. III. 
GENERA OF CHELYDR0ID2E. 
413 
greatest force to the bite of the animal : the mouth is narrow ; the jaws are 
strong; and their muscles are enormously developed, forming the great bulk of the 
head. In Chelydra the mouth is broader, the jaws are not so strong, and their 
muscles are less developed. Upon this general difference depend most of the dis- 
tinguishing characters of the two groups. 
I. Gypochelys, Ag. 
The skull of Gypochelys is very broad and high at the hind end, and rap- 
idly grows narrow and low thence forward; that part which includes the mouth 
and eyes and nose being very small in comparison with that which includes the 
fossa) temporales. The upper surface is nearly horizontal from side to side, and 
meets the sides at sharp angles ; it descends steeply from behind forward till 
between the eyes, where it makes an angle, and thence to the front end it is 
nearly horizontal ; it narrows continually forward from where it first reaches 
entirely across the head, but is still broad between the eyes, and blunt at the 
front end. The sides spread outward somewhat towards the lower edge between 
the ears and eyes, (that is, over the fossae temporales,) and thus the head grows 
broader downward ; but, in front of the fossae, the head is broader across the 
upper surface than across the mouth below. The eyes open sidewise and forward, 
not at all upward; the sides of the nasal region in front of the eye are nearly 
vertical; and the outer surface of the jaw is turned inward toward the alveolar 
edge, except at the symphysis, where it is on a nearly vertical line with the 
end of the nose above. Thus the mouth is narrow. The nasal region is high, 
and flattened sidewise. The upper jaw, at the symphysis, is drawn down to a long, 
strong point. On each side of this point the alveolar edge rises steeply, then 
curves down under the eye, and again a little upward at the hind end. The 
alveolar surface is carried high up under the nose, so as to form there an inverted, 
deep, conical pit. The pterygoids are narrow between the muscles of the jaw. 
The lower jaw is high and strong; and, like the upper one, it is drawn out at 
the symphysis to a long, strong point, which rises higher than the coronal angle. 
The outer surface, at the symphysis, curves far inward in descending from the 
upper to the lower edge, and, when the mouth is closed and the point of this 
jaw carried to the top of the pit above, there is a large space in front of this 
surface between it and the inner surface of the upper jaw. The strength of the 
jaws, the height of the lower one, the height of the head over the mouth, the 
narrowness of the mouth itself, and the height and width of the back part of the 
head, are all clearly connected with the force of the bite of the animal. The 414 
AMERICAN TESTUDINATA. 
Part II. 
neck is shorter than in Chelydra; this is owing to the size of the head; for 
such a head on a long neck would be cumbersome. The three ridges along the 
carapace are largely developed, and neither of them vanishes with age. The mar- 
ginal rim is thick, projecting far out beyond the carapace at the sides ; and at the 
front end it is deeply arched backwards, which is necessary to allow free motion 
to the large head. One scale covers the whole nose, above the horny sheath of 
the jaw. There is a characteristic row of scales, three in number, situated between 
the costal and marginal rows, over the union of the carapace and plastron, the 
addition of which is perhaps due to the great thickness of the marginal rim at 
that place, and two scales on each of the bridges of the plastron, within the 
row of three which crosses the ends. The whole neck and chin are covered 
with horny papillae of various sizes and forms. 
Gypochelys lacertina, Ag) Sufficient references to this species have already 
been given (p. 250). Its geographical range extends from western Georgia and 
north-western Florida, through Alabama, Mississippi, and Louisiana, to Texas. But 
I do not know exactly how far north it may be found in the valley of the 
Mississippi. I have lately received another young specimen from the neighbor- 
hood of New Orleans, through the kindness of Dr. Benedict, and compared other 
specimens from Mississippi, sent by Professor Wailes to the Museum of the Essex 
Institute in Salem, and also one belonging to the Museum of Oxford, Missis- 
sippi. Mr. Robert II. Gardiner has sent me one from south-western Georgia. They 
all agree in their generic and specific characters, and fully sustain the first 
observations of Dr. Holbrook.2 According to Professor Wailes, it measures some- 
times three feet in its greatest diameter. I insert below some interesting remarks 
respecting its habits, which have lately been communicated to me by Rev. Edw. 
Fontaine, of Austin, in Texas, who first observed it in that State. 
" I often have encounters with them when fishing for bass in our prairie 
rivulets. I saw one lying dead on the margin of a lake in Panola County, 
1 As this species is unquestionably the Chelydra 
lacertina of Schweigger, (Prodr., q. a.,) the specific 
name of Gyp. Temminckii, proposed by Troost and 
Dr. Holbrook, and adopted, p. 248, must give 
way to the older one, introduced by Schweigger. I 
am well aware that Dumeril and Bibron distinctly 
state (Erp. gen. vol. 2, p. 354) that Chelydra lacer- 
tina, Schw., is only founded upon an overgrown speci- 
men of Chelydra serpentina; but these very specific 
names show that Schweigger not only knew the two 
species of Chelydroids which inhabit the United 
States, but also perceived the differences in the scales 
under the tail, which distinguish them, and upon 
which I have insisted, (p. 412,) as generic characters ; 
and that he was aware how these peculiarities com- 
pare with the scales of Serpents and Lacertians. 
2 North American Herpetology, vol. 1, p. 147, 
pl. 24. Dr. Holbrook describes it under the name of 
Chelonura Temminckii; Dumeril, Cat. Rep. of the 
Jardin des Plantes, calls it Emysaurus Temminckii, 
adding, that he had already distinguished it in his man- 
uscript, as E. lacertina. Compare, however, note 1. Chap. HI. 
GENERA OF CHEL YDROID/E. 
415 
Mississippi, macle by an old bed of the great river, which measured nine inches 
between the eyes. I took no other measurement of its dimensions, and had 
no means of weighing it; but I am confident it would have weighed more than 
a hundred pounds. I saw the skull of one much smaller, caught by a gentle- 
man in the same county, which weighed seventy-five pounds. I have seen none 
of half that size in this vicinity. I kept two for several years in my fish-pond. 
They became very tame, but finding they were eating my fish I shot one, and 
wounded the other with a fish-gig; but his sagacity prevented my capturing him. 
I fed the perch and minnows with bread, which the alligator turtle1 devoured 
greedily. One day, after he had eaten, he remained upon the rock where I had 
fed him, and which was only about a foot beneath the surface, where it shelved 
over water ten feet deep. A swarm of minnows and perch were picking up 
crumbs around him, apparently unconscious of his presence. His head and feet 
were drawn sufficiently within his shell to be concealed. His mossy shell could 
not well be distinguished from the projections of the rock, on which he was 
lying in ambush. Several large bass were gliding around him, occasionally dart- 
ing at the minnows. One of these, about fourteen inches in length, came within 
striking distance of his head, which he suddenly thrust out and fastened upon 
him, fixing his aquiline bill deeply into his side and belly. He immediately 
drew the fish under him, and, holding him down firmly to the rock with his 
forefeet, ate him greedily, very much as a hawk devours its prey. I drew out 
a large line and hook and baited it with a minnow, and threw it to him, 
determined to get rid of this skilful angler. He seized it; I gave a sharp 
jerk, and fastened it in his lower jaw. Finding him too heavy to lift by the 
hook upon a rock six feet perpendicular, I led him around to the lower end 
of the pool, where the bank was low, and the water shallow. But, after getting 
him within a few feet of the edge of the water, he anchored himself by stretch- 
ing forward his forefeet, and resisted all my efforts to get him nearer. He 
seemed to be in a furious rage, and, after several sharp snaps at the line, he 
broke the hook and retreated into the deepest part of the pool. I never could 
get him to bite at any thing afterwards; and, finding I had a design upon his 
life, he became very shy. I afterwards discovered him in deep wTater, eating the 
bread which fell from the shelving rock, on which he had fed for several years, 
but upon which he never ventured afterwards when I was near. I threw a gig 
at him, and fastened it in his neck; but, by a violent effort with one of his 
forefeet, he tore it loose and ran under the rock. I frequently saw him after 
his escape, but always in the act of retreating to his hiding-place, which was 
1 This is the name given to this species in the Southern States. 416 
AMERICAN TESTUDINATA. 
Part II. 
entirely inaccessible. I intended sinking a steel-trap, baited with beef, to secure 
this sagacious old fellow, but my removal to the city side of the Colorado prob- 
ably saved his life; and I have but little doubt he yet lives and thrives upon 
the numerous fishes I left with him. If these two turtles made a nest or 
deposited their eggs while I had charge of them, I never discovered it. They 
kept all their love for one another, and their domestic affairs, a profound secret 
from their master. This species has a strong musky smell." 
A comparison of the young, (Pl. 5, fig. 23-27,) and of the eggs, (Pl. 7, fig. 
27,) with those of Chelydra serpentina, (Pl. 4, fig. 13-16; Pl. 5, fig. 18, 19, and 
Pl. 7, fig. 24-26,) will suffice to show the difference between these two remark- 
able Turtles. The color of Gypochelys lacertina varies from a light reddish or 
yellowish brown to an almost black tint. 
IL Chelydra, Schw. 
The head is smaller in Chelydra than in Gypochelys, the difference lying 
mostly in the relative size of the muscles which move the jaw, for the mouth 
is much broader here than in Gypochelys. The upper surface does not, as in 
Gypochelys, make an angle and lessen its descent in passing forward to the 
region of the eyes, but continues with one slope from the hind to the front 
end. The bony covering of the head, back of the eyes, is a low, flattened arch, 
spread out widely below, the sides making a very slight angle with the upper sur- 
face. The head widens downward also at the region of the eyes, and the orbits 
are near together at their upper edges and wide apart below, so that the eyes 
look upward as well as forward and sidewise. The upper and hind edges of 
the orbits project considerably beyond the skull, just between and behind them. 
The spreading apart downward of the sides of the front part of the head 
makes the mouth very broad. The nasal region is short, not high and flattened 
sidewise, as in Gypochelys, but rounded and conical, with the front end trun- 
cated. The outer surface of the jaw, at the front end, slants backward from the 
nose to the alveolar edge. The alveolar edge is prolonged downward at the 
symphysis to a small point; and on each side of the point the curve of the sides 
of the nasal region is continued down to the edge, and makes a short depres- 
sion in it: the edge curves down only slightly under the eye. The pit, in the 
alveolar surface at the front end, is very small. The pterygoids are broad 
between the muscles of the jaw. The lower jaw, like the upper one, is spread 
wider, and is lower and not so strong, as in Gypochelys. Its alveolar edge is 
pointed at the symphysis ; but the point is very small, and reaches no higher 
than the coronal angle. The ridges along the carapace are here less developed Chap. III. 
GENERA OF CIIEL YDR0ID2E. 
417 
than in Gypochelys, and almost disappear late in life. The marginal rim pro- 
jects only slightly at the sides beyond the carapace; its front end is much less 
arched backward than in Gypochelys. There are a pair of scales on the nose, above 
the horny sheath of the jaw. There is no row of scales between the marginal 
and costal rows. The scales on the plastron are less numerous than in Gypo- 
chelys ; one large one covers the whole bridge inside of the row of three which 
curves its outer edge. There are only two papillae under the chin. 
Chelydra serpentina, Schiv?- This is the well known Snapping Turtle of the 
United States, one of the most widely distributed species of this continent. It 
is found from Canada and Maine to Florida, and westward to the Missouri and 
to Louisiana. I have seen specimens from Ohio, from Indiana, from Iowa, from 
Missouri, and from Tennessee, not to speak of the Eastern and Middle States, 
where it is everywhere common; but I still entertain some doubts as to the iden- 
tity of the specimens from the Southern States.2 The color varies from light to 
dark brown. Its growth is much more rapid during the first ten or twelve 
years of its life than afterwards, as may easily be ascertained by a comparison 
of the relative distance of the lines of growth in the centre and at the edge of 
the scales of adult specimens.3 It is reported, upon reliable authority, that a 
specimen, marked forty-five years ago, only increased one inch in that time. 
The fossil species referred to the genus Chelydra seem to belong to two dis- 
tinct genera, resembling more closely in some respects the genera Chelydra and 
Gypochelys, while in other respects they are more closely allied to Platysternum, 
judging from the greater width of the anterior end of the sternum in Chelydra 
Murchisoni, and of the posterior end in Ch. Dechenii.4 
1 Although Linnaeus mentions Algiers and China 
as the home of his Testudo serpentina, there can be 
no doubt that it is our species, and that he was mis- 
taken as to its origin, the genus Chelydra being ex- 
clusively North American. Pennant mentions it as 
Testudo serrata, and Shaw as Testudo longicauda. 
The names under which it is most frequently quoted 
are Chelydra serpentina, Chelonura serpentina, and 
Emysaurus serpentinus. 
2 Specimens from Mobile and New Orleans show 
a wider emargination between the middle pair of the 
marginal plates of the hind margin than northern 
ones, and the keels of the back are less prominent. 
There are some other differences in the scales upon 
the bridge between the plastron and the shield; but I 
have not seen a sufficient number of specimens to be 
positive that all those found at the south agree in this 
respect, and constitute a distinct species. At all 
events, however, it is a remarkable variety, which 
does not occur at the north, and which I shall label 
Chelydra emarginata in my collection, until I have 
better opportunities of ascertaining the value of the 
differences thus far noticed. 
8 Judging from the lines of growth, specimens six 
and a half inches long and five and a half inches 
wide are only twelve years old; while others, which 
measure not more than twelve inches in length and 
nine and a quarter in width, are at least thirty-eight 
years old. 
4 Chelydra Murchisonii, Bell, (Trans. Geol. Soc. 
Lond., 2d ser., vol. 4, p. 279, pl. 24; H. von Meyer, 
zur Fauna der Vorwelt, p. 12, pl. 11 and 12, and Pa- 418 
AMERICAN TESTUDINATA. 
Part II. 
SECTION VII. 
GENERA OF CINOSTERNOID7E. 
Our knowledge of the genera and species of this family has progressed very 
slowly. For a long time only two species were known, which remained mixed 
up in the genus Terrapene with other species belonging to very different genera, 
until Fleming distinguished the genus Cistudo, Spix the genus Cinosternum, Bell 
the genus Sternothserus, and Wagler the genus Staurotypus, among which all the 
species thus far included in the genus Terrapene were at once divided, and new 
ones added. But, even after this first repartition of the species into several 
genera, much confusion continued to prevail in the nomenclature, as well as in 
the characteristics, of these animals. The name Terrapene, introduced in our 
science by Merrem, in 1820, to include all the fresh-water Turtles with a movable 
sternum,1 was limited, in 1825, to the Box Turtle, Cistudo, by J. E. Gray,2 while 
Bell still united heterogeneous species under that name.3 About ten years later, 
Canino applied the name Terrapene exclusively to the North American Emyds, 
and very properly retained the name Emys4 for the European species, to which 
it had been applied from the time of the first dismemberment of the old Lin- 
naean genus Testudo. The genus Cinosternum was from the beginning circum- 
scribed within natural limits by Spix,5 and maintained within the same limits by 
laeontogr., vol. 2, p. 238, pl. 26, 27, and 30,) has the 
front end of the plastron widened, as in Platysternum, 
while the posterior end is pointed, as in Chelydra. In 
Chelydra Dechenii, Myr., (Pateeontogr., p. 242, pl. 28, 
29, 30, fig. 5 and 6,) the case is exactly reversed. It 
is thus plain, that, while at the time of their first ap- 
pearance upon earth the representatives of this fam- 
ily were not constructed exactly as they now are, 
they yet foreshadowed, in the combination of their 
characters, the peculiarities that distinguish the living 
genera, two of which occur in North America and 
one in China, though none are found where the type 
first originated. 
1 Besides two species of Cinosternoidte, (Terra- 
pene Boscii and odorata, which are one and the same 
species, now called Ozotheca odorata, and Terrapene 
pennsylvanica and tricarinata, which are also identi- 
cal, and belong to the genus Thyrosternum,) the genus 
Terrapene, as limited by Merrem, (in his Testamen 
Systematis Amphibiorum, Marburgi, 1820,) embraces 
a genuine Sternothaerus, Terrapene nigricans, and two 
Cistudos, Terrapene clausa and amboinensis. 
2 Genera of Reptiles, in Ann. of Phil., vol. 10, 
p. 211. 
8 Monograph of the Tortoises having a movable 
sternum, in Zool. Journ., vol. 2, 1825, p. 299. In 
this paper Bell still unites the European Emys with 
the North American Cistudo as one genus, under the 
name of Terrapene. 
4 Chelon. Tab. Anal. 1836. In 1830, Wagler 
had already retained the name of Emys for the Eu- 
ropean species; but, like Bell, he still associated with 
it the Cistudos, which were at last duly distinguished 
by Canino. 
6 Spix, (J. B.,) Species nova? Testudinum et 
Ranarum, Monachii, 1824, 4to. Chap. III. 
GENERA OF CINOSTERNOIDS. 
419 
Wagler, Dumeril and Bibron, Fitzinger and others, while Gray1 unites Cinosternum 
and Staurotypus as one genus. The genus Sternothserus, on the contrary, has 
undergone many successive alterations. When first distinguished by Bell,2 it con- 
tained, besides its true representatives, a species also that belongs to a different 
genus, which I have called Ozotheca.3 Wagler having unfortunately introduced 
another name, Pelusios, for Bell's Sternothaerus, the latter was inappropriately 
limited by Fitzinger to Terrapene odorata, whilst Dumeril and Bibron4 referred 
this species to Wagler's genus Staurotypus,6 which ought, however, to embrace 
only its original type, the St. triporcatus. All the Cinosternoidae are American.6 
The assumption that the movability of the sternum7 indicates a close affinity 
among these Turtles has, to this day, prevented herpetologists from perceiving the 
family characters which distinguish the true Cinosternoidm from the Emydoidae, 
and likewise separate them from Sternothaerus, as shown above in the description 
of these families.8 Among the many fossil Testudinata thus far described there 
is not a fragment indicating that the family of Cinosternoidae has existed in ear- 
lier periods. This is the more surprising as its nearest relatives, the Chelydroids 
and the Emydoids, are well known to have existed in past ages. There is, 
however, a peculiar character prevailing in the family of Cinosternoidae, which it 
is difficult to express with precision, but which may yet account for their absence. 
Most types of animals and plants, when making their first appearance upon earth, 
are either marked by striking peculiarities, that make them stand out boldly 
among their contemporaries on account of their great difference, or they exhibit 
characteristics, in which the prominent features of later types are more or less 
blended together. Nothing of the kind exists in the Cinosternoids. On the con- 
trary, they are, as it were, abortive Testudinata, - dwarfish in size, abrupt and quick 
in their feeble movements, seeming young when full-grown; and yet, assuming very 
early the characteristic features of the adult, they are everywhere in the country 
mistaken for young Chelydroids. In all the species of which I had an oppor- 
tunity to examine numerous specimens I noticed marked differences between the 
males and females, consisting chiefly in the form of the front part of the shield, 
in the length of the tail, and in the scales of the legs.9 
1 Cat. Brit. Mus., 1834, p. 34. 
2 Zool. Journ., vol. 2, p. 305. 
8 Compare p. 251. 
4 Erp. gen., vol. 2, p. 358. 
6 Wagler, Nat. Syst. d. Amph., p. 137. 
6 Compare p. 302. 
7 Compare p. 346 and 418. 
8 See p. 346. Nothing can prove more directly 
the importance of a careful discrimination between 
family and generic characters than the changes which 
the classification of these genera has undergone. 
9 The difference in the form of the shield consists 
in the greater width of its front part in the female. 
The tail of the male is much longer and stronger than 
that of the female. There is, in the male, a patch of 
rough scales in the bend between the thigh and the leg. 420 
AMERICAN TESTUDINATA. 
Part II. 
The characteristic peculiarities of the eggs of the Cinosternoidae have already 
been mentioned (p. 350). Those of Thyrosternuni pennsylvanicum are represented 
Pl. 7, fig. 1-6; those of Ozotheca odorata, fig. 7-9. 
In the young Ozotheca odorata, and still more in the young Thyrosternum penn- 
sylvanicum, the characteristic features and forms of the family are already so 
fully developed during the first year, that we can hardly point out any change 
in their forms, from young to adult. This holds good, not only for the general 
proportions and outlines of the upper and lower shield, the feet, and the tail, 
but also for the scales. In the adult Emydoidaa, as well as in the Cinoster- 
noidae, the median scales of the carapace are generally narrower than the costal 
ones. This is already fully the case in all Cinosternoidae, at the time of hatch- 
ing; while in Emydoidm exactly the reverse obtains. (See p. 293, note 1, for 
a description of the young Chrysemys, and also Pl. 4 and 5.) In Thyrosternum, 
Platythyra and Ozotheca, the median scales of the back are, from the first year, 
not broader than long; while in Emyds they are at least twice, and often three 
times as broad during the first year as later in life. This peculiarity no 
doubt contributes to give them an oldish appearance from the beginning. There 
is another feature which makes the young Cinosternoidae look old: the rounded 
margin of the carapace and its steep curve behind, which are already fully 
marked, during the first year, in Thyrosternum and Platythyra. The sharper 
margin and the less prominent curve, which characterize Ozotheca in contradis- 
tinction to Cinosternon, are likewise strongly marked in the young Ozotheca, 
even more strongly than in the adult. Moreover, the tail has the same propor- 
tions from the first year to adult age. As the Cinosternoidse are walking Tur- 
tles, living in mud like the Chelydroidm, they do not need a long and high 
tail as a rudder. Notwithstanding this early development of the prominent feat- 
tures of these Turtles, we have to point out one interesting change in the 
Ozothecoids. When young, they are all high and carinated. These characters 
are brought out most fully in Goniochelys triquetra; while Ozotheca odorata, 
which, when young, shows the same height and the same keel on the back, 
grows more and more flat in course of time. 
The family of Cinosternoidae is composed of two well defined groups. In 
one, the true Cinosternoids, the plastron is large, and underlies nearly the whole 
body; the bridges which connect it with the carapace are long, and the first 
and fourth pairs of its bony plates are broad and rounded, and connected with 
the intermediate pairs by very flexible hinges. Thus the spaces around the free 
edges of the plastron are small, and, when the animal withdraws and raises the 
ends of the plastron, the soft parts of the body are almost entirely protected. 
In the other group, the Ozothecoids, the plastron is smaller; the bridges are shorter, Chap. III. 
GENERA OF CINOSTERNOIDS. 
421 
and descend less below the carapace; the fourth pair of bony plates is nar- 
rower at its front end, and narrows continually thence backward, its sides being 
straight, and not curved outward, as in the first group; and the sutures of the 
first and fourth pairs, with the second and third, are but slightly movable in the 
adult, and in some cases not at all so. Thus the spaces around the free edges 
of the plastron are here larger than in the first group; and besides, the protection 
from the shield is still less on account of the slight movability of the parts of 
the plastron upon one another. There are, besides, certain other tendencies that 
become important in connection with their constant characters. In Cinosternoids 
the tendency is to a more regularly arched carapace; in Ozothecoids, to a sharp 
ridge along the back, the sides spreading wide apart downward, so that the body 
is generally broader between the outer edges, but less deep below them, than in 
the first group. The scales on the plastron of the Cinosternoids are well devel- 
oped and well defined, and cover its whole surface; but in the Ozothecoids they 
are more irregular, and often separated by large, scaleless spaces between them; 
and the fourth pair of bony plates reaches forward on to the third pair, which 
is never the case in the Cinosternoids, for there it would interfere with the motion 
of the hinge. The scales of the shield differ also; in Ozothecoids they have 
a marked tendency to overlap those farther back, the centre of growth receding 
gradually backward of the centre of figure, as in the Chelonioids, and some exhibit 
even distinct traces of imbrication. In both groups there are two or more horny 
papillae under the chin. The principal differences between these groups all go 
to bring the body more under the protection of the shield in Cinosternoids than 
in Ozothecoids, and to give the legs freer motion in the latter than in the former. 
These characters are easily traced to corresponding habits of these animals; for, at 
least as far as we are acquainted with the members of these groups, the Cinoster- 
noids resort, in danger, more to the shield, the Ozothecoids, to flight; the former 
live more on land, the latter more in deep water, and are also the more shy, 
and the quicker in their motions. These characters, thus connected with the 
general form, and impressing upon it such decided tendencies, are clearly sub- 
family characters, and the groups themselves are sub-families. 
Within the limits of each of these sub-families of Cinosternoids, minor groups, 
containing one or more species, may be distinguished, that differ in the structure of 
the jaws and the parts dependent upon them, in the way of taking food, and, to 
some extent, in the kind of food sought; in short, in the voluntary organs of 
nutrition, and the parts concerned in it. At first sight, these groups, based on 
one set of organs, may seem arbitrary; but if it is remembered to what extent 
the acts of animals are directed to getting food, how far their sensations are 
gratified by this act, and how largely their instincts are concerned in it, it will 422 
AMERICAN TESTUDINATA. 
Part II. 
be plain that the characters of the immediate instruments of these acts are 
essential characters, and that any peculiarities and identities among them must be 
important in determining their natural relations. In Turtles the jaws and the 
neighboring parts are the principal organs concerned in these acts; and the claws 
and limbs, which generally perform so large a part in the movements connected 
with the function of nutrition in some of the higher types, have here little or 
nothing to do with it. Moreover, in Turtles the structure of the jaws and their 
muscles determine, to a great extent, the structure and form of the whole head. 
About the jaws and head, then, are we to look, in this order, for the structural 
characters which belong to the voluntary acts relating to nutrition; and here, and 
here only, do we find the distinguishing characters of the natural groups that may 
be distinguished within the families and sub-families. Months of research in the 
family of Cinosternoidae, and in corresponding groups of other families, have failed 
to point out any other organs as bearing distinctions and characters for these 
groups. Indeed, leaving out specific characters, it is impossible to identify any 
other part of the body of these animals, when examined isolatedly, as belonging 
to one or the other of these groups.1 It thus appears that there are, among 
Turtles, natural groups founded upon the organs with which these animals take 
their food, and upon them only. These groups, unquestionably, are genera. 
In preceding families I have not hesitated to insist at once upon the generic 
value of similar characters, trusting that the similarity in the range assigned 
to the genera which I was led to adopt upon such a foundation, with other gen- 
era already acknowledged as such, would not fail to convey the same conviction 
to the minds of other naturalists. But, the Cinosternoidae are to this day so imper- 
fectly known, the genera proposed by the ablest herpetologists are still so unsatis- 
factorily characterized, and, above all, the opinion expressed by Schlegel and Tem- 
minck2 upon these Turtles is so diametrically opposed to the results to which I have 
been led, that I felt it indispensable to show, on this occasion, in what way, and 
by what evidence, I have satisfied myself, step by step, that the family of Cinos- 
ternoidae is a natural family, embracing two distinct sub-families,3 each of which 
1 I mean to say, that parts of the body of a Turtle 
found separated, as is mostly the case with fossil re- 
mains, cannot be referred to their genus with cer- 
tainty, unless the jaws be among them ; or unless the 
parts found bear specific characters that occur only in 
well known genera. This result is of the utmost im- 
portance to Palaeontology, and may explain why 
Cuvier did not attempt to determine the generic char- 
acters, and to give specific names to many of the fos- 
sils which he described. It may also serve as a warn- 
ing to those palaeontologists who never hesitate to 
distinguish fossil species without sufficient preliminary 
comparisons with their living representatives, and 
sometimes upon the most insignificant fragments, 
which do not exhibit the first specific character. 
2 Fauna japonica; Chelonii, p. 59-62. 
8 Already alluded to, (p. 250 and 251,) when 
contrasting Ozotheca with the old genus Cinosternum. 423 
Chap. III. 
GENERA OF CINOSTERNOIDS. 
numbers several genera, and that its representatives are not all, as the celebrated 
naturalists of Leyden believe, varieties of only two species of the genus Emys. 
Of the groups thus distinguished as genera, there are three in the sub-family 
of Cinosternoids proper, namely, Cinosternum, Thyrosternum, and Platythyra; and 
three in the sub-family of Ozothecoids, namely, Goniochelys, Ozotheca, and Stau- 
rotypus. The colors prevailing in all these Turtles are dark, here and there 
enlivened by reddish or greenish or yellowish tints. 
GENERA OF THE SUB-FAMILY OF OZOTHECOIDS. 
Besides the Mexican genus Staurotypus, this sub-family embraces two genera 
that have representatives within the limits of the United States. 
I. Goniochelys, Ag. The jaws are very strong, and their muscles powerful. The 
strength of the upper jaw lies in the thickness of the bone; that of the lower 
jaw lies both in the thickness of the bone and the height of the jaw itself. 
To give room for the large muscles, the head is very broad across the fossae 
temporales. The sides of the head, back of the eye, spread wide apart down- 
ward ; the roof, between the orbits, is broad, but still they spread apart down- 
ward, and therefore open somewhat upward. The sides of the nose curve a little 
outward in passing down from the top. The jaw, under the eye, is very thick; 
its outer surface curves outward, and then again turns sharply inward to the alve- 
olar edge ; under the sides of the nose that surface slants also far inward ; 
while at the front end it slants backward, but not so much as it does at the 
sides. At the symphysis the jaw is drawn down more or less, and often consid- 
erably, to a point or a chisel edge. The horizontal alveolar surface is very broad, 
leaving but a small space within its angle. The lower jaw is both thick and 
high; it is drawn upward at the symphysis to a strong point ; its outer surface 
slants far inward from the alveolar edge at the sides, and backward at the end. 
The alveolar surface, as in the upper jaw, is very broad, and leaves but little 
space within its angle; it is broadest at the symphysis, and its inner edge curves 
somewhat inward in passing back to the hind end. It is nearly flat from side 
to side just before the angle, but has a ridge descending on to it from the 
angle. The scales of the shield have a marked tendency to imbrication. 
Goniochelys triquetra, Ag. Thus far this species has only been found in Lake 
Concordia, in Louisiana. I am indebted for specimens to Prof. Baird, Mr. B. 
Chase, and Prof. Wailes. Several specimens from the same source are preserved 
in the Museum of the Essex Institute in Salem. The most prominent specific 
character consists in the very sharp and high keel of the back, and the flat sides, 424 
AMERICAN TESTUDINATA. 
Part II. 
which give it a triangular form, in a front view. I shall describe this and the 
other new species more fully elsewhere, and give accurate figures of all of them. 
Goniochelys minor, Ag. The geographical range of this species is more exten- 
sive than that of the preceding. 1 first found it in the neighborhood of Mobile; 
but received afterwards other specimens from Columbus, Georgia, through the kind- 
ness of Dr. Gessner. Dr. Benedict also has sent me a specimen from New Orleans, 
and Dr. Nott others from Mobile. This species differs from the preceding by its 
smaller size, and more distinctly still by its arched sides, and the low keel of 
the back. In both species the scales are edged with black, and black lines or 
dots radiate from the posterior angle of the scales to their anterior and lowTer 
margins; but neither of them exhibits the characteristic stripes, which extend from 
the eyes to the neck, in the genuine Ozothecas. 
II. Ozotiieca, Ag. The jaws and their muscles are by no means wreak, but they 
are not as strong as in Goniochelys. The alveolar surfaces are not as broad, 
and the bones of the jaws not as thick, as in that genus, nor is the head as broad 
across the muscles which move the jaw. The sides of the head converge almost 
constantly from the ear to the front end; and they arch pretty regularly from above 
dowmward, back of the eye, and have no such sharp angles as there are in Gonio- 
chelys. The outer surface of the jaw slants inward almost directly from the 
orbit, and does not curve outward as far as in Goniochelys, if at all, so that the 
bone there is not so thick as it is in this genus. About the front end, that 
surface slants backward further than it slants inward at the sides, and the alve- 
olar edge rises there. Thus the nose projects far over the end of the jaw; and 
this, together with the constant approach of the sides of the head forward, makes 
the head very pointed in front. The jaw is never drawn down at the symphy- 
sis to a point of any size. The vertical alveolar surface is high all round, 
and is raised up somewhat under the nose; but it is never, either here or in 
Goniochelys, raised so high as in Cinosternoidse proper. The horizontal alveolar 
surface is not nearly as broad as in Goniochelys, and the space within its angle 
is much larger. The lower jaw is not as thick as in Goniochelys. It is some- 
what drawn outward and upward at the front end, not to a point, but to a curved 
end; its outer surface, at the sides, is nearly vertical; at the front end it curves 
far back, and this retreating part grows very broad downward. These latter char- 
acteristics are not plain till the animal is full-grown. The alveolar surface is 
not as broad as in Goniochelys; and it widens constantly from each side of the 
symphysis to the hind end. The ridge, spoken of as descending from the angle 
on to this surface in Goniochelys, exists also in this genus, but is less prominent, 
and is often merely a rising of the outer edge. The alveolar edges of both jaws 
are sharp, and the jaws are in every way well fitted for cutting. 425 
Chap. III. 
GENERA OF CINOSTERNOID^. 
Ozotheca odorata, Ag) This is the most common species of the sub-family. 
Its geographical range is very extensive, extending from New England to South 
Carolina, Georgia, and Western Florida, and westward to the Mississippi valley, as 
far as Missouri and Louisiana. I have specimens from Mobile, from New Orleans, 
from Tennessee, and from western Missouri, which leave no doubt upon this point, 
and for which I am indebted to Dr. Nott, Dr. Benedict, and Professor Baird. The 
color varies greatly, from light to dark brown, with or without spots. Major 
LeConte has described, under the name of Cinosternum guttatum,2 specimens from 
Pennsylvania, in which the spots are unusually numerous and distinct. I have 
satisfied myself, however, by a careful comparison of the original specimen which 
Major LeConte had the kindness to intrust to me for examination, and of many 
others from the same locality, (Upper Darby, Pennsylvania,) sent me by Prof. 
Baird, and from other localities by Dr. Hallowell, that this is a mere variety of 
our common Ozotheca odorata. I have found similar specimens in Cambridge, 
-among others that varied from a uniform tint to a more or less dotted surface. 
The young are represented Pl. 4, fig. 1-6;3 the eggs, Pl. 7, fig. 7-9. 
Ozotheca tristycha, Ag. This species is only found in the Western and South- 
western States. I have many specimens, collected by Mr. G. Stolley, in the 
Osage River, in Missouri, and in Williamson County in Texas. Prof. Baird has 
sent me four young belonging to the Smithsonian Institution, that were obtained 
by Dr. C. B. Kennerly, near San Antonio, and two others from the Medina River, 
in Texas. The young are represented Pl. 5, fig. 20-22. Although Ozotheca odo- 
rata varies greatly, not only in color, but even in outline, I have no doubt that 
this is a distinct species, characterized, when young, by the great prominence of 
the keels upon the vertebral and costal plates4 and by numerous dark dots between 
the scales of the sternum, and when adult by a marked difference in the form 
of the snout. In Ozotheca odorata the snout is much more prominent, on account 
of the slope of the upper jaw, which extends further back, and is therefore less 
steep, than in Ozotheca tristycha, the lower jaw of which is broader below the 
symphysis than in Ozotheca odorata, and suddenly turned up. 
1 This species has been referred to so many gen- 
era that it appears, in different works, under more 
names than any other North American Turtle. Its 
oldest name is Testudo odorata, which was afterwards 
changed to Terrapene odorata, Cistudo odorata, Ster- 
nothterus odoratus, Cinosternum odoratum, Emys 
odorata, Staurotypus odoratus. Testudo glutinosa, 
Emys glutinosa, Terrapene Boscii, and Sternotluerus 
Boscii are other synonymous names. (Comp. Holbr. 
N. Am. Herp. p. 133, and Dumeril and Bibx'on, Erp. 
gen. vol. 2, p. 358.) 
2 Proceed. Acad. Nat. Sc., Philad., 1854, p. 185 
and 189. 
8 The figure of a young, two years old, shows 
how the scales increase only along the anterior and 
lateral margins, thus tending to give them an imbri- 
cated appearance. 
4 Comp. Pl. 4, fig. 1-6, and Pl. 5, fig. 20-22. 426 
AMERICAN TESTUDINATA. 
Part II. 
GENERA OF THE SUB-FAMILY OF CINOSTERNOID.E PROPER. 
I. Cinosternum, Spix. The jaws are strong; their horizontal alveolar surfaces are 
broad, and they seem well fitted for crushing ; their strength comes from thick- 
ness, and not from height. The head is very broad: the upper maxillaries spread 
wide apart backward; the sides of the head continue to spread back of them till 
about midway between the eyes and ears ; and thence backward they approach 
each other. They also spread rapidly apart from above downward, just back of 
the eyes. The front part of the head over the mouth is low; its roof between the 
eyes is broad; and the eye-orbits open sidewise and forward, not upward. The nose 
is short; its sides curve out somewhat from above downward, and its roof reaches 
as far forward as the jaw under it. The mouth is very short, and, as the upper 
maxillaries spread so wide apart backward, it is very broad behind. The outer 
surface of the maxillaries curves outward under the eye, and then turns sharply 
inward to the alveolar edge; but at the symphysis the jaw is drawn down to 
a sharp point or a short chisel-edge, and the outer surface at the end slants 
backward less than it slants inward at the sides. The horizontal alveolar surface 
is very broad, narrowest at and near the symphysis, and widening fast thence 
backward to the hind end. The lower jaw is low, but its outer surface curves 
far backward from the end and inward from the sides, and its alveolar surface 
is broad; thus it is thick and strong. The alveolar edge is bluntly rounded at 
the front end, and not drawn out to a sharp point. The alveolar surface is 
narrowest at the symphysis and on either side of it, but widens fast thence 
backward, and is broadest at the hind end ; at and near the angle it is almost 
flat from side to side, but its outer edge rises considerably about the front end. 
The outer surface of the jaw curves outward considerably below the alveolar edge, 
thus making the jaws shut the closer. 
No species of this genus are known to occur within the limits of the United 
States ; but there are several in Central and South America, which have gener- 
ally been confounded with the Testudo scorpioides of Linnaeus. Major LeConte 
was the first to distinguish them carefully.1 It is true the species from the Brazils 
1 Dumeril and Bibron, (Erp. gen. 2 vol. p. 32,) 
as well as Gray, (Cat. Brit. Mus. 1844, p. 32,) agree 
in considering Bell's Cinosternum shavianum, and 
Spix's Cinosternum longicaudatum and brevicauda- 
tum, as synonymes of Testudo scorpioides, Lin.; 
but Major LeConte, in his interesting monograph of 
the genus Cinosternum, (Proc. Acad. Nat. Sc. Phil. 
1854, p. 180,) has clearly shown that the Brazilian 
specimens constitute a distinct species from that of 
Surinam, which is the old Linnsean species, and that 
the Mexican is still different. I have myself exam- 
ined the specimens upon which his descriptions are Chap. III. 
427 
GENERA OF CINOSTERNOIDJE. 
was first described by Spix, but under two distinct names. As I have possessed 
for a long time several living specimens of the species found in Mexico, and of that 
of Surinam, sent me by Prof. Baird and Mr. C. J. Hering, and compared specimens 
of the third, I can vouch for the accuracy of the distinctions traced by M. LeConte. 
II. Thyrosternum, Ag. The jaws are strong, and well fitted for cutting, but not 
for crushing. The head is not as broad as in Cinosternum; it arches back of 
the eyes, but is not as wide spread as in Cinosternum, and its sides between 
the eyes and ears are gently curved outward, and have no such sharp angle as 
in that genus; it is high over the mouth, and its roof there is broad between 
the eyes, so that the orbits open sidewise and forward, not upward. The nose 
is long and high; its roof reaches as far forward as the jaw reaches under it, and 
its sides approach each other downward very fast. The mouth is long and narrow; 
the outer surface of the jaws curves outward under the eye, and then again turns 
sharply in to the alveolar edge; and further forward also, under the sides of the 
nose, it curves far inward, but at the symphysis the jaw is drawn down to a 
short chisel-edge, and its front surface slants back but little. The vertical alve- 
olar surface is high all round, but especially so at the front end, where it projects 
downward, and where also it is often raised high up under the nose. The horizontal 
alveolar surface is broad at the symphysis, and narrowest on each side of it, and 
widens thence backward; but it is not nearly as broad as in Cinosternum. The 
lower jaw is strong. It gets its strength, not by its thickness, as in Cinosternum, 
but by its height. It is very high all round ; sometimes it is drawn far up at 
the symphysis to a long, slender point. The outer surface at the sides is nearly 
vertical for some distance below the edge. The alveolar surface of the lower 
jaw is much narrower than in Cinosternum, except at the symphysis, where it is 
nearly vertical ; near the angle it is almost horizontal, but its outer edge rises 
somewhat. The cutting edges of this jaw pass close within those of the upper 
based, and agree with him as to the validity of these 
species. I have only a few objections to his nomen- 
clature. His Cin. mexicanum is identical with Bell's 
Cin. shavianum. Bell's description (Zool. Journ. vol. 2, 
p. 302) is based upon the identical specimen figured by 
Shaw, from the Leverian Museum, and agrees in every 
respect with those described by Maj. LeConte, who 
indeed refers to the same figure of Shaw, also quoted 
by Bell. (Shaw, Gen. Zool. vol. 3, p. 61, pl. 15, erro- 
neously referred to Staurotypus triporcatus by Wagler.) 
The name Cin. mexicanum, therefore, must be given 
up. As to Cin. longicaudatum and brevicaudatum, I 
disagree with LeConte in one respect, - he considers 
the two species of Spix as distinct; I believe, with 
Wagler, (Syst. Amph. p. 137,) that they are the male 
and female of the same species. Cinosternum cruen- 
tatum (Dum. and Bibr., Arch. Mus. 1852, vol. 6, p. 
238, pl. 16) belongs also to this genus ; but, as I had 
no opportunity of comparing it with the three others, 
I am unable to say whether it is a distinct species or 
not. We have thus at least three distinct species of 
Cinosternum proper: Cin. scorpioides, Wagl., (Tes- 
tudo scorpioides, Lin.,) Cin. shavianum, Bell, (Cin. 
mexicanum, LeC.,) and Cin. longicaudatum, Spix, 
(including his brevicaudatum,) and perhaps a fourth, 
Cin. cruentatum, Dum. and Bibr. 428 
AMERICAN TESTUDINATA. 
Part II. 
one as the jaws shut. These edges are sharp in both jaws. Fish and Coleopte- 
rous insects were found in the intestines of two specimens examined immediately 
after their capture; the Fish in the one, and the insects in the other. The spe- 
cies of this genus have, to this day, been associated with the genuine Cinoster- 
nums of Central and South America; but the characters indicated above show 
them to differ generically. 
I know three species of this genus, one of which has long been known under 
the name of Testudo pennsylvanica; the others were first described by Wagler, 
Gray, Dumeril and Bibron, and Major LeConte, under the names of Cin. hirtipes, 
Wagl.? Cin. oblongum, Gray? Cin. Doubledayii, Gray? Cin. leucostomum, Dum. and 
Bibr.? Cin. integrum, LeC.? and Cin. sonoriense, LeC.',^ but these species are by no 
means all distinct. 
Tiiyrosternum pennsylvanicum, Ag? The young are represented Pl. 4, fig. 7-12, 
and Pl. 5, fig. 16 and 17 ; and the eggs, Pl. 7, fig. 1-6, under the name of 
Cinosternum pennsylvanicum. Cinosternum oblongum Gray is only a male, and 
not a distinct species. Dr. Nott has sent me a specimen with a double row of 
median scales along the back. This is the only instance of an anomaly I have seen 
in the scales of any Cinosternoid. The geographical range of this species is very 
extensive. It occurs from Pennsylvania to Florida, and westward to the Missis- 
sippi valley. I am obliged to Dr. Nott for specimens from Pensacola and Mobile, 
and for others to Mr. Albert Stein, from the last locality. Dr. Benedict and Mr. 
T. C. Copes have sent me large numbers from the neighborhood of New Orleans. 
Tiiyrosternum sonoriense, Ag. The young are represented Pl. 5, fig. 8-11, under 
the name of Cinosternum sonoriense, LeC. This species has thus far only been 
found in Mexico, but so near upon the borders of the United States that it 
deserves to be noticed here. Tucson, in Sonora, is the locality whence Dr. J. 
LeConte obtained the specimen described by his father.5 Others from the same 
locality, and from Guadalupe Canon, also in Sonora, are in the possession of 
the Smithsonian Institution. 
1 Syst. Amph., p. 137, tab. 5, fig. 29 and 30 ; 
Descr. et leones, pl. 30. 
2 Cat. Brit. Mus., p. 33. 
8 Arch. Mus., 1852, vol. 6, p. 239, pl. 17. 
4 Proc. Acad. Nat. Sc., Phil. 1854, p. 183. 
6 Ibid. p. 184. 
6 This is the Cinosternum pennsylvanicum of mod- 
ern authors, (comp. Dum. and Bibr., Erp. gen., vol. 
2, p. 367, and Holbrook, N. Am. Herp. p. 367,) called 
also Terrapene pennsylvanica, Cistudo pennsylvanica, 
Emys pennsylvanica, and Testudo subrufa. I have 
not the slightest doubt that the Testudo tricarinata, 
Uetz, in Schopff's Hist. Test., (Daudin's Testudo 
Retzii,) which is generally referred to Cinosternum 
scorpioides on account of the dorsal keels, is the 
young of this same species. A comparison of my 
figures (ph 4, fig. 7-9) with Schopff's pl. 2, fig. 1-3 
will satisfy the most skeptical. Schopff's figures rep- 
resent a specimen two years old; mine were recently 
hatched. Chap. III. 
GENERA OF CINOSTERNOIML 
429 
Tiiyrosternum integrum, Ag. LeConte's Cinosternum integrum from Mexico (Proc. 
Acad. Nat. Sc. Phil., 1854, p. 183). This species resembles Wagler's Cinosternum 
hirtipes, which belongs also to this genus. Wagler's species is founded upon a 
single male, preserved in the Museum of Munich, LeConte's upon a single female 
in his possession. I have examined both. The rough scales in the knee joint of 
the hind legs of Th. hirtipes are a sexual character, found in all the male Cinos- 
ternoids, and do not by any means constitute a specific distinction. The differ- 
ence in the outline of the front margin of the carapace and the absence of an 
odd marginal scale in Cinosternum hirtipes may prove specific, though a tendency 
to such differences is already noticeable among the males and females of Th. penn- 
sylvanicum. I have not seen Cin. Doubledayii, Gray ; but I doubt its specific differ- 
ence from C. pennsylvanicum, as well as its Californian origin. Nor have I seen Cin. 
leucostomum, Dum. and Bibr.; but I have often noticed specimens of Cin. pennsyl- 
vanicum with a white jaw, especially among the females, and Dumeril and Bibron's 
species is founded upon a female. 
III. Platythyra, Ag. The jaws are very weak; the mouth is broad and short. 
The head is long and low; it is regularly arched, back of the eyes ; its sides 
curve slightly between the eyes and ears; its roof is very narrow between the 
eyes, and, as the mouth below is broad, the eye-orbits are carried far outward 
at their lower edges, and therefore open upward as well as forward and side- 
wise. The skull does not rise back of the orbits; indeed, the orbits project above 
it at their upper edges. The nose is short, much shorter than in Cinosternum; 
its outer surface curves all round it, so that, when the fleshy parts are preserved, 
it is rounded and pointed; its bony roof does not project forward as far as the jaw 
projects under it. The outer surface of the jaw slants inward under the eyes, curv- 
ing out, above the alveolar edge, very little if at all; at the front end it slants 
backward faster than it slants inward at the sides, and the alveolar edge rises there; 
but just at the symphysis the jaw is brought down to a small, short point. The 
upper maxillaries are narrow from above downward, and weak. The vertical alve- 
olar surface is not as high as in Thyrosternum ; the horizontal alveolar sur- 
face is broad, but the bone under it is thin. The lower jaw is also weak, being 
very thin, especially about the symphysis, and not high, as in Thyrosternum. 
It is drawn out at the symphysis to a slender point. The alveolar surface is 
narrow all round; in front it is nearly vertical, and it flattens toward the angle, 
but near the angle the outer edge is raised somewhat more than in the other 
genera. The outer surface of the sides curves considerably outward for a short 
distance below the edge near the angle, and the jaws shut close. These jaws 
are clearly not fitted to tear any strong, fibrous substance; the only food found 
in the intestines of a specimen examined with that view was a mass of insects. 
The type of this genus is altogether new to science. 430 
AMERICAN TESTUDINATA. 
Part II. 
Platythyra flavescens, Ag. I have examined several specimens of this species, 
sent to me by the Smithsonian Institution. Some of them were obtained in 
Texas, near San Antonio, and upon the Lower Rio Grande; others on the Red 
River, Arkansas; and others at Camp Yuma, on the Gila River, by Dr. R. 0. 
Abbott. It is of a yellowish green color; the scales are imbricated, and edged 
with black. The young are represented Pl. 5, fig. 12-15. 
SECTION VIII. 
THE GENERA OF EMYDOIDJE. 
From want of sufficient materials, I cannot attempt to characterize all the 
genera of this numerous family, and shall have to limit myself to the North 
American types. Fortunately these are numerous enough to enable me to show 
upon what features the genera are founded; even though I do not intend to 
enter here into such minute details of their characteristics as I have presented 
for the genera of the preceding families,1 excepting where this becomes necessary 
to establish the validity of the new genera which I have recognized. The Che- 
lydroids and Cinosternoids being excluded from the Emydoids, this family appears 
here circumscribed within narrower limits than those assigned to it by previous 
writers. All its American representatives are included by most modern herpe- 
tologists in two genera, Emys and Cistudo,2 to which J. E. Gray has added the 
genus Malaclemys, and two sub-genera, Chrysemys and Lutremys.3 They all lay 
oblong eggs, and the young when hatched are circular in outline in all of them;4 
but, even at that time, they vary in various ways in different genera and 
sub-families. The differences between the males and females are not so constant 
as in some other families. It is, however, generally the case that the males are 
flatter and more elongated. It will not be possible to determine accurately the 
period of the first appearance of this family in past geological ages, until the 
1 My object, in this second part of my work, is 
chiefly to show in what manner the principles advo- 
cated in the first part may be applied in illustrating 
any special group of animals. Having done this in 
the preceding sections as far as I am prepared to do 
it now, it would be superfluous to extend farther this 
analysis of the Testudinata. Moreover, the genera 
of Emydoidte are too numerous to allow this to be 
done satisfactorily, without enlarging too much the 
bulk of this volume. As to the species, I have lim- 
ited myself to mere hints, because I intend to give 
elsewhere full descriptions with figures of the new 
ones. 
2 Compare p. 251 and 252. 
8 Cat. Brit. Mus., 1844, p. 27, 28, 31. 
4 See p. 292 and 38G. Chap. HL 
GENERA OF EMYDOIDS. 
431 
remains of this order have been compared anew to ascertain which are genuine 
Emydoids, and which Hydraspides. The modifications noticed in the form have 
suggested their subdivision into several tribes or sub-families. (Compare p. 355.) 
GENERA OF THE SUB-FAMILY OF NECTEMYDOHLE. 
I. Ptychemys, Ag. Horizontal alveolar surface of the upper as well as the 
lower jaw very broad, and divided by a ridge, the crest of which is tuberculate, 
and parallel to the cutting edge of the jaws. This edge is either smooth or 
serrate. The front of the alveolar margin of the upper jaw is either emargi- 
nated or more or less deeply notched, with or without a projecting tooth on 
either side (Pl. 27, fig. 5). Lower jaw very flat, with a hook or sharp point in 
front, behind which a keel extends along the symphysis, on each side of which 
there is a deep pit; alveolar surface spreading inward beyond the vertical branches 
of the jaw. Horny sheath of the lower jaw rough externally. A row of large 
scales, in the shape of a fold, along the outer edge of the forefeet (Pl. 27, fig. 
1-3). Tessellation of the epidermis, amounting to scales upon the neck, but not 
upon the loose skin between the legs. The clawless fifth toe of the hind foot 
forms an angular projection on the posterior edge of the foot (Pl. 27, fig. 1-3). 
The color varies greatly with age, and even in different specimens of the same 
age. When young, the whole surface has more or less confluent ocellated and 
crescent or lozenge-shaped figures, which become more transverse afterwards, and 
may be resolved into simple blotches in old age. The claws also vary greatly 
in length and strength; sometimes, especially in half grown specimens, those of 
the three middle toes exceed the length of the whole foot. In the young, the 
median row of scales forms a blunt keel along the back, which fades entirely in 
the adult. The scales are at first smooth, or rather finely granulated; afterwards 
radiating rugosities appear upon their periphery, while in old age1 they are lon- 
gitudinally rugose. 
Ptychemys rugosa, Ag? Its most prominent specific character consists in the 
1 This shows how unsatisfactory specific charac- 
ters must be which are derived from the direction, or 
even the presence, of these rugosities. 
2 This species is well known to the American 
naturalists, under the name of Emys rubriventris, 
(Holbrook, N. Amer. Herp., vol. 1, p. 55, pl. 6,) 
first applied to it by Major LeConte ; but, as this able 
observer has himself acknowledged, (Proc. Ac. Nat. 
Sc. Phil., 1854, p. 189,) it had been described before, 
by Shaw, as Testudo rugosa. Merrem and Schlegel 
consider it as a variety of Emys serrata, while Say 
and Harlan have actually confounded it with Emys 
serrata, from which it differs, even generically. Gray 
also describes it as Emys serrata, (Emys irrigata, 
Bell). Emys rivulata, Gray, is not specifically dis- 
tinct. Dumeril and Bibron describe it under three 432 
AMERICAN TESTUDINATA. 
Part II. 
more elongated form of the adult, the greater plainness of the color of the back, 
the strong, coarse serratures of the upper and lower jaw, and the prominent hooks 
on both sides of the median notch of the upper jaw. The geographical range of 
this species is very limited; it extends only from New Jersey to Virginia. I have 
received a large number of specimens of all ages from Washington, through the 
kindness of Professor Baird. A series of them are represented on Pl. 26 and 
27, with the view of showing what is the range of variations in some species 
of this family. These plates tell their own story. The yellow, hieroglyphic 
ocelli and curved lines extending upon a gray ground over the whole surface 
of the shield (Pl. 26, fig. 1-4) gradually pass (fig. 5) into a system of more 
parallel lines, (fig. 6, 9, 10, and 11,) transverse upon the costal scales, (fig. 6 
and 10,) more longitudinal upon the median scales, (fig. 9 and 11,) and ocellated 
upon the marginal scales, and the yellow bands deepen gradually to orange, (fig. 
9 and 10,) the ground being more greenish (fig. 6) or deeper brown (fig. 5); 
or the lineated appearance vanishes entirely, and the surface becomes mottled 
(fig. 7). The sternum is at first yellow, with black blotches (fig. 4); but grad- 
ually becomes reddish, (fig. 8,) and even deep red, without a spot. In the adult, 
the mottled appearance of the shield prevails, and only faint traces of the trans- 
verse bands remain, (Pl. 27, fig. 1,) the general color being either gray mottled 
with red, or deep red mottled with black. Occasionally the whole surface is dark, 
and only slightly mottled or faintly banded with brownish red. It would have 
taken two or three more plates to represent all the variations of color I have 
observed.1 I have only seen immature eggs of this species. 
Ptychemys concinna, Ag? This species occurs from the southern parts of North 
Carolina, through all the southern States as far as western Louisiana, and up the 
Mississippi valley as far as Arkansas. I have received a large number of speci- 
mens, through the kindness of Dr. W. B. Daniell, from Savannah; of N. A. Pratt, Jr., 
from Roswell, Georgia; of Dr. R. W. Jeffries, from Pensacola, Florida; of Dr. Hol- 
brook, and Dr. Nott, from Mobile; of Professor Chilton, from New Orleans; of Mr. 
W. Sargent, from Natchez; of Professor Wailes, and Dr. L. Harper, from other 
different names, as Emys rugosa, Emys irrigata, and 
Emys rubriventris (Erp. gener., vol. 2, p. 284, 276, 
and 281). 
1 This shows plainly that there are genera among 
our Emydoids in which neither the tint nor the pat- 
tern of coloration affords any specific characters. 
2 Few species of American Emyds have been 
more extensively mistaken than this. It was first 
described, in 1820, by Major LeConte, as Testudo 
concinna (Emys concinna, Dum. and Bibr.; Holbr. 
N. Am. Herp., vol. i., p. 119, pl. 19) ; but at the same 
time he gave another name, Testudo floridana, (Emys 
floridana, Hari.; Holbr. N. Am. Herp., vol. i., p. 65, 
pl. 8,) to large specimens observed by him in Florida. 
Besides adopting these two species, Gray described it 
also under the name of Emys ornata, and the young 
under that of Emys annulifera. Cat. Brit. Mus., p. 
22 and 27. Chap. HI. 
GENERA OF EMYDOIDJE. 
433 
localities in Mississippi ; of Mr. G. Stolley, from Arkansas and Texas. Professor 
Baird lias sent specimens to me, collected by Dr. Hoy in south-western Missouri, and 
others from Tarboro', North Carolina. It is considered everywhere at the South 
as the most delicious kind of Terrapene. The young are represented Pl. 1, 
fig. 13, and Pl. 2, fig. 4-6 ;1 the eggs (Pl. 7a, fig. 20-23) vary much more 
in size and form than those of any other species in the family. This is also 
the case with the adults, which, as far as the form is concerned, vary much 
more than Ptychemys rugosa, though the range of variations in the colors is less. 
Some are very elongated, and narrower in front and behind than across the 
middle;2 others are broad, and evenly rounded at both ends.3 Some are flat; others 
very high, especially behind the shoulders;4 and some have a very blunt head, while 
in others the snout is more prominent. Before I knew that the blunt form of 
the head was an embryonic feature which is sometimes preserved to advanced 
age, I had distinguished such specimens under the name of Ptychemys Hoyi. 
The most prominent character of the species consists in the comparative smooth- 
ness of the upper jaw, and the slight emargination of its edge, which is rather 
arched than notched; the lower jaw, however, is distinctly serrated, though less 
evenly than in Ptychemys rugosa and mobiliensis, and provided with a smaller 
and less prominent hook. 
Ptychemys mobiliensis, Ag? It is easily distinguished from the other species 
of the genus by the great height of the anterior part of the back, and still 
more by the serrature of both jaws; the lower, however, is more strongly and 
more coarsely serrated than the upper, which is deeply notched in the centre, 
with a prominent tooth on each side; there is a marked hook in the lower jaw. Its 
geographical range is believed to be rather limited. It is said not to be found 
west of Mobile Bay, where it is common, and to abound in Pensacola. I 
owe all the specimens I have from these localities to Drs. Nott and Holbrook; 
but others were sent to me from New Orleans by Professor Chilton, and from 
Guadalupe Mountains, Pecos River, Texas, and New Leon, near Cadereita, Mexico, 
by the Smithsonian Institution, so that this species extends much further west than 
is generally supposed. There can be no doubt upon the point, as, besides the 
specimens sent to me by the Smithsonian Institution, I have received young speci- 
mens, collected in Texas, by Mr. G. Stolley. The young are represented Pl. 3, fig. 
14-16; the eggs (Pl. 7a, fig. 24 and 25) are larger and less variable than those 
of Ptychemys concinna. 
1 This is Gray's Emys annulifera. 
2 This is the Testudo (Emys) concinna, Le C. 
8 This is the Emys ornata of Bell. 
4 This is the Testudo (Emys) floridana, Le C. 
5 First described by Dr. Holbrook as Emys mo- 
biliensis, vol. 1, p. 71, pl. 9. 434 
AMERICAN TESTUDINATA. 
Part II. 
Ptychemys hieroglyphica, Ag? Only known from the middle Western and South- 
ern States. 1 have seen neither the young nor the eggs. 1 owe my specimens to 
the kindness of Dr. Gessner, of Columbus, Georgia. Dr. Holbrook describes it 
from Tennessee. The upper jaw is emarginated, but smooth ; the lower jaw is 
thinner and more feeble than in other species, and its edge also smooth. The 
inner rows of tubercles in both jaws are more continuous. The whole body is 
very flat, and the hind margin more deeply serrated than in the other species. 
Ptychemys decussata, Ag? This species is not found within the borders of 
the United States. It is a native of Cuba. But, as I had an opportunity of 
comparing specimens forwarded to the Smithsonian Institution by Professor Poey 
of Havana, I avail myself of this opportunity to state that it is a distinct 
species of the genus Ptychemys, more nearly allied to Ptychemys concinna than 
to any other. 
II. Trachemys, Ag. The chief difference between Trachemys and Ptychemys 
consists in the horizontal alveolar surfaces of the jaws, which are much nar- 
rower in Trachemys than in Ptychemys. The ridge of the upper jaw is less 
prominent, low in front, and not tuberculated ; the lower jaw does not spread 
horizontally, and has only a slight, smooth inner ridge. There is a notch in the 
front of the upper jaw, but no lateral teeth; the lower jaw is arched upwards, 
and terminates in a hook. The marginal scales are separated by notches, and 
the edges of the scales again are themselves notched. The tessellation of the 
skin amounts to scales upon the neck, and upon the loose skin between the legs 
and the shield ; but the form of the feet is the same as in Ptychemys. The 
young have a slight, obtuse median keel, and their scales are finely gran- 
ulated. Their color is very characteristic; there are numerous longitudinal bands 
upon the median scales, and transverse ones upon the costal scales, while the 
marginal scales are ornamented with crescent shaped figures. As the animal grows, 
the bands become less and less numerous, or disappear completely in old age. 
At first smooth, they afterwards assume radiating ridges, up to the seventh or 
eighth year; and, finally, longitudinal ridges and rugosities prevail upon the scales. 
(Compare p. 431, note 1.) 
Trachemys scabra, Ag? This species extends from North Carolina to Geor- 
1 First described by Dr. Holbrook, N. Am. Herp. 
p. Ill, pl. 17. In the figure of Dr. Holbrook, the 
smallness of the head is somewhat exaggerated. 
2 This is the Emys decussata of Bell, figured by 
Ramon de la Sagra, Cuba, Rept., pl. 1. 
Emys Berardi, Dum. and Bibr., seems also to be- 
long to this genus, judging from the description and 
the figures of the jaws published by A. Dumeril, Arch. 
Mus. vol. 6, p. 231, pl. 15. 
8 This species is generally known under the name 
of Emys serrata (Ilolbr. N. Am. Herp., vol. 1, p. 49, 
pl. 5). It is also described as Testudo scripta, Schn., 
Emys scripta, Schw. But, since it is undoubtedly the 
Testudo scabra of Linnaeus, I have restored its oldest Chap. HI. 
GENERA OF EMYDOIDJE. 
435 
gia.1 I have received specimens from Wilmington, North Carolina, through Mr. 
S. T. Abert; and from Savannah, Georgia, through Dr. W. B. Daniell. I am, how- 
ever, indebted for the largest numbers to Dr. Holbrook. Professor Baird has also 
sent me many young from Savannah. The young are represented Pl. 2, fig. 13- 
15. I have never been able to obtain its eggs. It is easily distinguished by its 
broad outline and great height; keeled along the back, coarsely tuberculated and 
rugose all over the shield, and deeply notched behind. There is a broad, trans- 
verse, light-yellow band across the neck, behind the eye. 
Trachemys Troostii, Ay.2 In the Western States, from Missouri and Illinois to 
Tennessee and Louisiana. All the specimens I have seen were sent to me by 
Mr. G. Stolley, from the Osage River, Missouri; by Dr. Watson, from Quincy, Illi- 
nois ; and by Professor Wailes, from Washington, Mississippi. Dr. Holbrook men- 
tions it from Tennessee. It represents, in the valley of the Mississippi, the 
Trachemys scabra of the southern Atlantic States, and differs from it by its 
more elongated and flattened form, the absence of a median keel, the less coarse 
tubercles and rugosities of the shield, the less marked notches of the hind mar- 
gin, the dark, mottled neck, and the total absence of longitudinal and transverse 
bands upon the neck. I have seen neither the young nor the eggs. 
Trachemys elegans, Ag? This species is easily recognized by its smoothness 
and flatness, and the bright blood-red longitudinal band which extends on each 
side of the neck. It is not as broad as Trachemys scabra. Its geographical 
distribution is very remarkable. It is found from the Upper Missouri to Texas; 
but it does not extend to the eastward beyond the lower course of the Ohio. 
I have received specimens from the Osage River and from Texas, through Mr. G. 
Stolley; from Burlington, Iowa, through Dr. J. Rauch; from Quincy, Illinois, through 
Dr. Watson; from Mississippi and Louisiana, through Mr. W. Sargent, Professor Wailes, 
and Dr. Benedict; and from the Yellow Stone, one of the head waters of the Mis- 
souri, from the neighborhood of San Antonio, from Matamoras, from the Brazos, 
name. This circumstance removes a part of the con- 
fusion introduced in the synonymy of our Turtles, in 
the application of the name of serrata to different 
species. Testudo serrata, Pen., is Chelydra serpenti- 
na ; Testudo (Emys) serrata, Say and Gray, is Ptych- 
emys rugosa; Testudo serrata, Daud., is Trachemys 
scabra; Testudo scabra, Shaw, is Emys trijuga, Schw. 
1 Dumeril erroneously quotes New York among 
the localities where it occurs. Emys vittata, Gr., does 
not differ specifically. 
2 The first and only complete description is that 
of Dr. Holbrook, N. Am. Herp., vol. 1, p. 123, pl. 20. 
Temminck and Schlegel have confounded it with the 
preceding species. 
8 First described by Prince Max. von Neu-Wied 
as Emys elegans (Reise Nord-Amer., vol. 1, p. 213). 
Dr. Holbrook has described and figured it under the 
name of Emys cumberlandensis, N. Am. Herp., p. 
115, pl. 18. Gray gives it the name of Emys Hol- 
brookii, in the Cat. Brit. Mus., 1844, p 23. Pro- 
fessor Wailes mentions it, in his Geol. Rep., under 
the name of Emys Terrapin. 436 
AMERICAN TESTUDINATA. 
Part II. 
and from Brownsville, in Texas, through the Smithsonian Institution. There can 
be no doubt, therefore, that this species extends over the most extraordinary 
range; which is more difficult to explain than that of any American Emyd. The 
young are represented Pl. 3, fig. 9-11; the eggs, Pl. 7 a, fig. 18 and 19. 
Trachemys rugosa, Ag? I mention this species only to state that it differs 
from its North American representatives by its elongated form, the slight notches 
of the hind margin, and the very coarse rugosities of the back. There is a 
light longitudinal band on the side of the neck. Its color varies from a light 
salmon to a dark gray. I have seen specimens from the Havana, sent by Pro- 
fessor Poey to the Smithsonian Institution. 
III. Graptemys, Ag. The great width of the smooth and flat horizontal alveolar 
surface, and the spoon shaped dilatation of the extremity of the lower jaw, chiefly 
distinguish this genus. There is no notch in the upper jaw. The tessellation 
of the skin amounts to scales only on the back of the neck; but there are large 
scales upon the feet, and a row of prominent ones along the outer edge of the 
fore legs. The young are strongly keeled, and their margin deeply notched, espe- 
cially behind and on the sides, with a smooth surface, as prevails also in the 
adults; in old specimens, the concentric lines of growth of the scales are some- 
times distinct. The persistence of the keel along the middle line of the back 
in the adults seems to be a character of inferiority, considering that it disap- 
pears in many species which are keeled when young, as, for instance, in Ptyche- 
mys. Though I had no opportunity of comparing specimens of Gray's Emys 
sinensis, I consider it as the Chinese representative of this genus. May not Emys 
Bennettii, Gr., also belong to this group ? 
Graptemys geographica, Ag? Common from Pennsylvania and New York to 
Michigan, Tennessee, and Arkansas. I am indebted for specimens from Michigan 
to Prof. A. Winchell, of Ann-Arbor; from Quincy, Illinois, to Dr. Watson; from 
Delphi, Indiana, to Mr. Franklin Hill; from Ohio, to Mr. George Clark, of Toledo, 
to Mr. Joseph Clark, of Cincinnati, and to Dr. Kirkland, of Rockport; from 
Pennsylvania, to Prof. Baird, and S. S. Haldeman; from Blount county, Tennessee, 
to Prof. Baird; and from Arkansas, to Mr. G. Stolley. The young are represented 
Pl. 2, fig. 7-9; the eggs Pl. 7a, fig. 28-30. 
Graptemys LeSueurii, Ag? This species is only known in the Western States, 
1 This is the Emys rugosa of Gray, but not of 
Shaw. It is figured by Ramon de la Sagra, Cuba, 
Rept., pl. 2. Gray's E. vermiculata (Cat. Brit. Mus., 
1844, p. 25) is the same. 
2 First described by LeSueur under the name of 
Testudo geographica. Dr. Holbrook called it Emys 
macrocephala, in the first edition of the N. Am. Ilerp. 
In the second he adopted LeSueur's name (p. 87). 
Emys labyrinthica LeS. is only a variety of this spe- 
cies, remarkable for the numerous meandering lines 
upon the bridges of the sternum. 
8 This species is commonly called Emys pseudo- Chap. III. 
GENERA OF EMYDOID2E. 
437 
where it ranges from Michigan, Wisconsin, and Iowa, to Louisiana. I have 
received specimens from Burlington, Iowa, through Dr. J. Rauch; from Marion 
County, Missouri, through the Smithsonian Institution; from the Osage River, 
through Mr. G. Stolley; from Maumee River, Ohio, through Mr. Geo. Clark; from 
Arkansas, through Mr. G. Stolley, and the Smithsonian Institution. Judging from 
the many specimens sent me by Mr. W. Sargent and Professor Wailes, it must 
be common about Natchez. The young are represented Pl. 2, fig. 10-12 ; the 
eggs Pl. 7a, fig. 31-34. The eggs vary more in form than those of Graptemys 
geographica, as the animal itself also does. 
IV. Malacoclemmys, Gray) A very distinct genus, first noticed by J. E. Gray, 
who refers only one species to it, though I believe that his E. Bealii is the Chinese 
representative of ours. There are no scales on either side of the neck, the 
upper arms, the thighs, or the loose skin of the legs, but merely a tessellation 
of the epidermis; distinct scales only upon the legs, arms, and feet. Inguinal or 
axillary scales small or wanting. Head long and peaked, or blunt, short, and 
rounded.2 Horny sheath of jaws straight, strong, and smooth ; horizontal alveo- 
lar surface fiat and broad, without ridges ; alveolar edges meeting at an angle 
in the upper jaw, and tapering to a triangle in the lower. Young keeled, 
adults tuberculated, upon the middle line. The median scales remain longer 
broad than in any other Emydoid, indicating a lower standing, which agrees with 
its mode of life in salt-marshes. 
Malacoclemmys palustris, Ay? Common along the Atlantic coast, in salt-marshes, 
from New York to Texas, and even to South America. Specimens from the 
States bordering on the Gulf of Mexico are generally smaller than those of the 
Atlantic States, and have the edge of the carapace more turned up;4 but such 
specimens occur even in the vicinity of New York. This species varies most 
remarkably in its color and sculpture, as well as in the size of the head. The 
lighter varieties are plain greenish gray, the darkest almost black; there are those 
with concentric stripes upon the scales, alternately dark and light colored; some are 
entirely smooth, and others have deep concentric grooves, indicating the successive 
lines of growth of the scales. The sternum varies from light yellow or yellow- 
geographica ; but the specific name LeSueurii is older. 
It is evident from his reference that Gray at first ap- 
plied the name of Emys LeSueurii to this species, and 
not to Gr. geographica; now Gray calls it also Emys 
pseudo-geographica. Prof. Wailes enumerates it in 
his Geol. Report under the name of Emys serrata. 
1 Though Gray spells this name Malaclemys, I 
have altered it to suit its etymology. 
2 There is not another genus the head of which 
varies as much in size and form as this. 
3 Malaclemys concentrica, Gray, Cat. Brit. Mus. 
1844, p. 28. It is the Testudo terrapin, Schoepff, 
Emys terrapin, Holbr., Test, centrata, Daud., Test, 
concentrica, Shaw, Test, palustris, Gmel. and Le C. 
4 This is probably the Emys areolata, A. Dum. 
Arch. Mus., vol. 6, p. 223, Pl. 14. 438 
AMERICAN TESTUDINATA. 
Part II. 
ish green to reddish brown, plain, or dotted or striped concentrically. I am 
indebted to Prof. Baird for a large series of specimens from the Middle States; Dr. 
Nott has sent me others from the Gulf States. Dr. Holbrook's figure (Pl. 12) rep- 
resents a broad-headed variety; DeKay's, (Zoology of New York, Pl. 3, fig. 5,) one 
with a pointed head.1 The young are represented Pl. 1, fig. 10-12; the eggs, Pl. 
7a, fig. 11-14. 
V. Chrysemys, Gray. Although J. E. Gray considers these Turtles only as a 
sub-genus of Emys, I am satisfied that they belong to a distinct genus, the rep- 
resentatives of which are closely allied to the other Nectemyds, and not to the 
Clemmyds, as Wagler supposed. The large web of their feet and the broad hori- 
zontal alveolar surface of the upper jaw show this distinctly, even though the 
horny sheath that covers its edge be narrow. They die in a few days when kept 
out of the water, while the Clemmyds are much more terrestrial, and may be kept 
for months on dry ground during the hottest days of the summer. This is the case, 
at least, with Glyptemys insculpta. The most prominent generic character con- 
sists in a notch in front of the horny sheath of the upper jaw, on each side of 
which the edge of the sheath projects more or less to form lateral teeth, that 
are close together. The young are not keeled2 at all, and are flatter than 
those of the other genera. The colors are very constant, and afford good specific 
characters.'3 
Chrysemys picta, Gray? This species may be at once distinguished from the 
other species of the same genus by the form of the middle row of scales upon 
the back, and the manner in which the costal scales6 of the carapace meet those 
of the vertebral row, and also by a broad, yellow band, limited by a black line, 
which extends along their anterior margin. The ground color is dark, grayish 
brown; the margin has intensely blood-red blotches. The scales of the median 
row have their lateral angle higher up, and the upper margin of the lateral 
scales nearly on a line with the upper margin of the median scales, while in 
all the other species the median scales are more regularly hexagonal, and the 
1 J. E. Gray's Emys macrocephalus, Cat. Brit. 
Mus. 1844, p. 26, is a large-headed variety of this 
species. 
2 The absence of a keel in the young, and the small 
size of the adult, seem to indicate that this genus 
stands highest in its sub-family. 
8 The only variations that I have noticed corre- 
spond to the changes which take place with age ; there 
is, though very rarely, some difference in the extent 
of the lyriform figure upon the sternum. 
4 This is the well-known Emys picta of most 
modern herpetologists, the Testudo picta of Hermann 
and Schneider; Testudo cinerea, Brown, Emys cine- 
rea, Schw., is the young. Seba already mentions it 
as Testudo ex Nova Hispania. It also appears as 
Terrapene picta in Prince Canino's works. Wagler 
calls it Clemmys picta. 
5 Occasional anomalies are observed in the form 
of the scales. Prof. S. S. Haldeman has sent me one 
specimen in which one of the costal scales and the pos- 
terior median scales of the back are divided ; and an- 
other in which there is one additional costal scale. Chap. HI. 
GENERA OF EMYD0ID2E. 
439 
upper margin of the lateral scales is on a line with the lateral angle of the 
median scales. This is already visible in the youngest specimens, at the time 
of hatching. (Comp. Pl. 1, fig. 4 and 5 with fig. 6 ; also Pl. 3, fig. 1 ; Pl. 5, 
fig. 2 ; and Pl. 6, fig. 8 ; compare also p. 293, note). The sternum is golden 
yellow ; occasionally, but very rarely, with a partial lyriform figure ; now and 
then also a streak or a dot may be seen upon the costal scales. But the form 
of the scales shows this species to differ strikingly from the others. The eggs 
are represented Pl. 7a, fig. 1-3. Chrysemys picta is described as occurring every- 
where in the United States; but this is incorrect. It occurs only in the Eastern 
and Middle States as far as the northern boundary of South Carolina, whence it 
extends to the north-western parts of Georgia. Its northern-most boundary is 
New Brunswick, according to Mr. M. II. Perley. I have obtained specimens from 
North Carolina, through Mr. W. C. Kerr, and from western Georgia, through Mr. Al. 
Gerhardt. I have never observed it in the Southern States, nor further west than 
the western parts of Pennsylvania and New York, and the eastern parts of Ohio. 
In western Ohio, in Indiana, Wisconsin, and Michigan, it is replaced by Chrysemys 
marginata; in Missouri, and parts of Illinois, by Chrysemys Bellii; in Minesota, by 
Chrysemys oregonensis; and in Louisiana and Mississippi, by Chrysemys dorsalis. 
Chrysemys marginata, Ag. It is flatter, broader, and more rounded than Chrys- 
emys picta ; the bands between the scales of the carapace are either yellow or 
blood-red, narrower than in Ch. picta, but bordered with more distinct black lines. 
Their lateral margins exhibit parallel ridges, while in Chrysemys picta they are per- 
fectly even. The ground color is bronze green, with a few red or yellow spots. 
Upon the sternum there is a black lyriform blotch, as in Chrysemys Bellii, but 
narrow and plain, and not mottled (see Pl. 5, fig. 3). This figure is, however, occa- 
sionally wanting. The young are represented Pl. 1, fig. 6, and Pl. 5, fig. 1-4 ; 
the eggs (Pl. 7a, fig. 4-6) are larger than in Ch. picta, though the animals are 
of the same size. I am indebted for specimens of this species to Dr. P. R. Hoy, 
of Racine, Wisconsin; to Mr. J. A. Lapham, of Milwaukee, Wisconsin; to Dr. Manly 
Miles, of Flint, Michigan ; to Professor Alex. Winchell, of Ann-Arbor, Michigan; 
to Mr. Franklin Hill, of Delphi, Indiana; and to Dr. Rauch, of Burlington, Iowa. 
One specimen was sent to me from Rome, in the State of New York ; but I 
cannot ascertain by whom, nor whether it had been found in that State. 
Chrysemys Bellii, Cray} By its form, this species resembles more Chrysemys 
picta than Chrysemys marginata; but the scales of the carapace are arranged as 
1 Synops. Rept. in Griffith's An. Kingd., 1831, p. 
31, under the name of Emys Bellii. The generic 
name Chrysemys is first introduced in the Cat. Brit. 
Mus. 1844, p. 27, where Mr. Gray states that this 
species is named Emys speciosa by Clift in the Cat. 
Mus. Coll. Surg. No. 1525. 440 
AMERICAN TESTUDINATA. 
Part II. 
in the latter, while the margin of the costal scales is smooth. There are a 
few irregular yellow or red bands across the costal scales, with a few red dots. 
The ground color is copper-red, or bronze colored. The lyriform black blotch of 
the sternum has lateral angular projections. I have received many specimens 
from the Osage River, in Missouri, through Mr. G. Stolley. Dr. George Engel- 
mann has also sent me many from St. Louis; and I have found it myself in 
western Illinois. The young are represented Pl. 6, fig. 8 and 9. 
Chrysemys oregonensis, Ag* Mr. Nuttall, who discovered this species, states that 
it was found in Oregon; Prince Max von Neu-Wied observed it near Fort Union, 
on the Upper Missouri. I have received specimens from the Smithsonian Insti- 
tution, collected near Fort Snelling, Minesota, in the Yellow Stone River, Nebraska, 
and among the Guadalupe Mountains, in Texas. My friend James M. Barnard has 
brought me a living specimen from White Bear Lake, Minesota, which agrees exactly 
with Dr. Holbrook's original specimen, now in the Museum of the Academy of 
Natural Sciences, in Philadelphia. The back has numerous yellow lines upon a 
greenish ground, and the sternum regular blotches in the form of a lyre all over 
its surface. The young represented (Pl. 3, fig. 1-3) belongs to the Smithsonian 
Institution. 
Chrysemys dorsalis, Ag. I have seen only a few specimens of this species, 
the only one of the genus which I have not kept alive for a considerable time. 
They were sent to me by Prof. Wailes, who collected them in the States of Mis- 
sissippi and Louisiana.2 Lake Concordia is the locality whence most specimens were 
obtained. The Smithsonian Institution possesses specimens from the same source. 
This is the broadest and shortest species of the genus. It is easily distinguished 
by the great width of the median scales of the carapace; their form resembles 
more that of the scales of the young Ch. picta than that of the adults of other 
species. Margin of the costal scales plicated, as in Ch. marginata. As in Ch. 
picta, the sternum is uniformly golden yellow. The yellow median stripe along the 
back is broader than in any other species. The marginal scales are not so 
highly ornamented as in other species. Indeed, the characteristic, crescent-shaped 
figures of the margin occur only upon the lower surface, and are quite pale. 
1 This is Harlan's Emys oregonensis (Am. Journ. 
Sc., vol. 31, p. 382, pl. 31, and Holbrook's N. Am. 
Herp. vol. 1, p. 107, pl. 16). I have great doubts re- 
specting the accuracy of the statement of Nuttall, that 
this species was found in Oregon. It has never been 
seen in that territory by the many expeditions which 
have explored it since Nuttall; nor did Dr. Picker- 
ing notice it when there with the United States Ex- 
ploring Expedition. I am therefore inclined to believe 
that he made some mistake in reference to its origin. 
2 I suppose that the specimens carried from New 
Orleans to Paris by Mr. Trecul, and referred to 
Emys picta by Dumeril, belong to this species. I 
have never seen Ch. picta anywhere in the States 
bordering on the Gulf of Mexico. Prof. Mailes also 
quotes this species as Emys picta in his Geol. Rep. Chap. HI. 
GENERA OF EMYD0ID2E. 
441 
SUB-FAMILY OF THE DEIROCHELYOimE. 
This sub-family embraces only a single genus, as for as I know, and to this 
day that genus numbers a single species, the North American Emys reticulata, 
Schweig}- In many respects it recalls the Australian Chelodime, by the unusual 
length of its neck; but differs strikingly from them by the mode of articula- 
tion of its neck vertebrae. It is a genuine Cryptodeira, and in no way allied 
to the Pleurodeirte.2 
Deirochelys, Ag. The upper jaw is notched in front; the lower jaw is low, 
arched upwards, and terminates in a sharp point. 
Deirochelys reticulata, Ag. The geographical range of this species is much 
more extensive than is generally supposed. It is found in all the Southern 
States, from the southern parts of North Carolina to Louisiana, though it seems 
to be nowhere very common. I have obtained specimens from North Carolina, 
through Mr. S. Th. Abert and Dr. C. L. Hunter; from South Carolina, through Dr. 
Holbrook; from Pensacola, through Dr. R. W. Jeffries; from Mobile, through Dr. 
Nott; and from Red River, Louisiana, through Professor Baird. The young are 
represented Pl. L, fig. 14-16, and Pl. IL, fig. 1-3 ; and the eggs, Pl. VII., fig. 17-19. 
* 
GENERA OF THE SUB-FAMILY OF EVEMYDOIDtE. 
Emys, Brongn? All modern herpetologists, with the exception of Dr. Holbrook 
and Maj. LeConte, have confounded the North American representative of this 
genus with the common Box Turtle,4 Cistudo virginea, with which it is only 
remotely allied. The distinguishing character of the genus consists in the nar- 
row, horizontal alveolar surface, and the narrow, horny sheath of the bill, which 
is notched in front, the alveolar edge rising gradually to form a triangular 
emargination, while under the eye it is arched down. No part of the plastron 
is sutured to the carapace; the median pair of bones are united to it by unos- 
sified, flexible derm; the plastron itself is hinged at the middle transverse suture, 
and the two movable plates, thus hinged upon one another, are raised to the 
1 Compare Holb. N. Amer. Herp. p. 59, pl. 7. 
It is the Testudo reticulata, Bose.; Terrapere reticu- 
lata, Bonap. 
2 Compare p. 335, note, and 351. 
3 Gray has proposed the name Lutremys for this 
genus; but the older name, Emys, must be pre- 
served. He has further subdivided the Cistudos, 
with which he associates the genus Lutremys, into 
Cistudo proper and . Cyclemys. 
4 Dum. and Bibr. Erp. g(^n. vol. 2, p. 210 ; Gray, 
Cat. Brit. Mus. p. 30. Comp, also my remarks, p. 
249 and 252. 442 
AMERICAN TESTUDINATA. 
Part II. 
carapace when the animal withdraws into the shield for protection. (Compare 
the Cinosternoids, p. 348.) In Cistudo the beak projects downward. The head is 
long and wide, its front part spreading apart downward, so that the eyes open 
upward, and the mouth is broad; while in Cistudo the head is high, the sides 
of its front part nearly vertical, and the mouth narrow. The lower jaw is low, 
and arched upward to a point in front, its alveolar surface being almost vertical. 
Emys Meleagris, Ag) The young are nearly circular, and entirely black above, 
without a spot, and the scales granular; the sternum is also black, with a white 
edge. They are represented Pl. 4, fig. 20-22 ; and the eggs, Pl. 7a, fig. 2G and 27. 
As they grow larger, they elongate rapidly ; indeed, this species is comparatively 
longer than its European representative, the Emys lutaria. This is truly Shaw's 
Testudo Meleagris, notwithstanding Shaw's own recantation. The young might be 
confounded with the figure of Emys pulchella, Schopff, which is the young of 
the European species. This species extends through the Northern States, from 
New England to Wisconsin. It has been found in Massachusetts, near Lancaster, 
by Dr. W. I. Burnett and Mr. S. Tenney, and in Concord by Mr. I). II. Thoreau. 
I have specimens from Michigan, sent to me from Ann-Arbor by Professor Al. Win- 
chell and by Dr. A. Sager, and from Flint by Dr. Manly Miles, and from Wiscon- 
sin by Dr. Hoy, of Racine. 
GENERA OF THE SUB-FAMILY OF CLEMMYD0ID.E. 
It was Wagler who first showed that there are several genera included in 
the old genus Emys, even after removing the genera now referred to the fam- 
ilies of Cinosternoids and Chelydroids. Among these genera there is one, Clem- 
mys, which constitutes a distinct sub-family,2 embracing still several distinct genera, 
four of which are characteristic of the Faume of North America. 
I. Nanemys, Ag. Edge of upper jaw straight, slightly notched in front; lower 
jaw slightly arched upward;3 snout rounded, and its sides not compressed lat- 
erally ; neck and loose skin between the legs scaly. Large scales upon the 
legs and feet. 
Nanemys guttata, Ag^ The young are represented Pl. 1, fig. 7-9; the eggs, 
1 Major LeConte was the first to notice that the 
North American Cistudo Blandingii is synonymous 
with Shaw's Testudo Meleagris; but he calls it Lu- 
tremys Meleagris. 
2 Comp. p. 356. 
3 The upper jaw may occasionally have a deeper 
notch in front, and the sides of the notch may be 
tooth-like; but the bill never projects downward 
as in Calemys. 
4 This is the well-known Emys guttata of modern 
herpetologists. The best figure is that of Dr. Hol- 
brook's, N. Am. Herp., pl. 11. It is also known Chap. III. 
GENERA OF EMYDOIDJE. 
443 
Pl. 7a, fig. 7-10. Its yellow dots upon a black ground are very characteristic. 
When hatched, there is but a single dot upon each scale of the shield, and 
none upon the marginal scales; as it advances in age new dots appear, one by 
one, upon each scale, until they become very irregular, and extend to the margin 
of the shield. I have, however, seen old specimens that were entirely black, and 
others in which the dots remained few and regular. The sternum varies from 
black to yellow, with black blotches, especially upon the centres of the scales. This 
species is common in New England, and in the middle Atlantic States. It does 
not extend south of North Carolina, nor west of New York and Pennsylvania. 
I have received large numbers from North Carolina, through the kindness of 
Professor Baird, but never noticed it in the South or in the West. 
II. Calemys, Ag. This genus differs from Nanemys in having a deep notch 
in front of the upper jaw, with a large tooth on each side, projecting in the 
shape of an arched bill. Sides of the head compressed, but not narrowing down- 
ward. The lower jaw is strongly arched upward.1 
Calemys Muhlenbergii, aL/.2 I have never seen the young, or the mature eggs 
of this species, which seems rather rare, and entirely limited to New Jersey and 
the eastern parts of Pennsylvania. Its scales are either perfectly smooth or 
concentrically grooved; with or without keel along the back. The dark orange 
blotch on each side of the neck, extending over the temporal muscles, is charac- 
teristic of this species. 
III. Glyptemys, Ag. The upper jaw projects in the form of a bill, arched down- 
ward, notched at the tip, and so compressed sidewise that the margin of the 
mouth is narrower than the top of the forehead over the nose. The edge of 
the lower jaw is straight, except the tip, which is greatly arched upward. The 
horny sheath of the horizontal alveolar surface is narrow in both jaws. The 
margin of the shield is very thin and spreading in the young, and the surface 
of the scales is coarsely granular. In the adult they have radiating ridges, 
which in very old age are sometimes entirely smoothed down. 
Glyptemys insculpta, Ag? This species is common in the North-eastern States, 
and is found only as far south as New Jersey. I am indebted to Mr. S. Ten- 
ney for hundreds of specimens from Lancaster, Massachusetts. He has also secured 
under the names of Emys punctata and Clemmys 
punctata. 
1 As I have not seen the young, I am some- 
what doubtful respecting the value of the differ- 
ences pointed out between this genus and the pre- 
ceding. 
2 This species is well represented by Dr. IIol- 
brook, in his N. A. Herp. pl. 4, under the name of 
Emys Miihlenbergii. 
3 This is the Emys insculpta of Major LeConte. 
Dumeril and Bibron have erroneously identified it 
with Schoepff's Testudo pulchella, which is the young 
of the European Emys lutaria. Emys speciosa, 
Bell, is the smooth variety of the old age. 444 
AMERICAN TESTUDINATA. 
Part II. 
a .specimen for me from the Little Madawaska River, in lat. 47° north, Maine. 
There is less difference in the length of the tail in the males and females 
than in Actinemys marmorata. 
IV. Actinemys, Ag. Edge of the upper jaw straight, with a notch in front; 
lower jaw broad at the symphysis toward the lower edge, strong, and strongly 
arched upward. Males, with a long, tapering tail ; in the females the tail is 
short and blunt. Young, with radiating striae upon the scales, the centre of 
which remains for a long time granular, as in Testudo tabulata. Adults, smooth. 
Actinemys marmorata, Ag} Varies from green to black, mottled with light dots, 
more or less radiating. Light yellowish below; a few specimens have the black 
angle of the sternal scales that characterizes Glyptemys insculpta. 
This is the only species of Emydoid known from the western slope of the 
continent of North America. I have received a fine series of specimens from 
San Francisco, California, from my friend, T. G. Cary, Jr. I have also exam- 
ined a number of specimens belonging to the Smithsonian Institute, among which 
are the originals of Baird and Girard's Emys marmorata, and of Dr. Hallowell's 
Emys nigra. The former species is founded upon the young, the latter upon the 
black variety of the adult. It appears from these specimens that Actinemys 
marmorata is found from Puget Sound to Monterey, California. 
Three out of five genera of this sub-family are characteristic of New Eng- 
land and the middle Atlantic States, while the fourth is exclusively found in Cali- 
fornia, and the fifth in Europe. There are no representatives of this type in the 
Western or Southern States. This is particularly remarkable, when considered in 
connection with the similarity which exists between the ichthyology of Europe and 
that of New England, and the striking contrast there is between that of the lat- 
ter region and the other ichthyological Faunae of North America. 
THE SUB-FAMILY OF CISTUDININA. 
I have already stated, (p. 251,) that the genus Cistudo should be limited to 
the North American Box Turtles, and that it differs widely from the true genus 
Emys, with which it is generally associated. 
Cistudo, Flem. Head, very high. The temporal arch is either cartilaginous or 
only partially ossified. Horizontal alveolar edge, narrow; beak of the upper jaw 
projecting downward, with or without a notch in the middle ; lower jaw, sharp- 
1 This is Baird and Girard's Emys marmorata, 
Proc. Ac. Nat. Sc. Phil. 1852, p. 177, described 
also under the name of Emys nigra, by Dr. Hal 
lowell, Proc. Ac. Nat. Sc. Phil. 1854, p. 91. Chap. HL 
GENERA OF EMYDOIDAE. 
445 
pointed in front. Hind foot, plantigrade. The plastron is attached and hinged 
essentially as in Emys. It is probable that the difference between the manner 
in which the plastron is moved in the Cinosternoidae and in the Emydoidae with 
movable sternum depends on family characters, and that a single hinge could 
not exist in the Cinosternoidm, nor a double one in the Emydoid. 
Though I have examined many hundred specimens of this genus, I do not yet 
feel justified' in expressing a decided opinion respecting the value of the differ- 
ences which I have noticed among them, as they were mostly adults. The dif- 
ferences noticed may indicate different species ; but they may also mark only vari- 
eties. There is, however, a remarkable circumstance connected with the specimens 
that came under my observation : their variations are limited to particular regions 
of the country. A satisfactory investigation of this genus would therefore involve 
the whole question of local and climatic varieties. 
Cistudo virginea, Ag) The north-eastern type of the genus has the most 
extensive range. It is found in New England, and westward as far as Michi- 
gan, and southward as far as the Carolinas. I have received three-toed speci- 
mens from North Carolina, through Mr. W. C. Kerr, which agreed in every other 
respect with those of New England. The young are represented Pl. 4, fig. 17-19 ; 
the eggs, Pl. 7, fig. 10-14. 
Cistudo triunguis, Ag? The western and south-western type is remarkable for 
having, almost universally, only three toes to the hind feet. Specimens from Lou- 
isiana and Mississippi are particularly small, and of a pale yellowish color, with a 
few spots. The eggs are represented Pl. 7, fig. 15 and 16. I have received a 
very large number of specimens from Dr. Benedict and Mr. T. C. Copes, of New 
Orleans, all of which agree in their small size and pale color. Had I not 
noticed a few larger specimens from the Osage River and from Georgia, I should 
not hesitate to consider them as a distinct species. 
Cistudo ornata, Ag? The north-western type is round, broad, and flat, with- 
out keel, even when young, (Pl. HL, fig. 12 and 13,) while the young of Cistudo 
virginea are always strongly keeled. I have received specimens from the Upper 
Missouri through the Smithsonian Institution, and from Iowa through Dr. J. Rauch. 
Cistudo major, Ag. The southern and south-eastern type grows to a very 
large size, and is more oblong than the others. I have received specimens from 
Mobile through Dr. Nott, and from Florida through Mr. Fr. W. Putnam. 
1 This is the Cistudo Carolina of most authors, 
Grew's Testudo virginea. Gray's Emys kinoster- 
noides is the young. 
2 Gray has described a three-toed Cistudo from 
Mexico as a distinct genus, under the name of 
Onychotria Mexicana. Proc. Zool. Soc. of London, 
1849. The outer toe of the hind foot hides away so 
gradually that the genus Onychotria cannot stand. 
3 Of all the Cistudo which I have seen, this is 
most likely to be a distinct species. 446 
AMERICAN TESTUDINATA. 
Part II. 
SECTION IX. 
GENERA OF TESTUDININA. 
Were it not for the circumstance that Linnaeus has united all Testudinata into 
one genus, I believe the classification of this order would long ago have been 
more natural than it is now. To this day only eight genera have been referred 
to the family of Testudinina, though its species are very diversified, and exhibit, 
no doubt, characters indicating generic differences beyond those acknowledged at 
present, if I may judge from the few that have come under my inspection. The 
name of Testudo must of course be preserved for that genus to which the 
common European T. grmca belongs. Wagler lias already separated from it the 
T. marginata under the name of Chersus, and Fitzinger has applied the name of 
Chelonoidis to Testudo tabulata, that of Geochelone to T. stellata, that of Psammo- 
bates to T. geometrica, and that of Megalochelys to T. indica ; while Gray has re- 
tained the name Chersina for T. angulata, and Dumeril and Bibron have established 
the genus Homopus, not to allude to the genera Pyxis and Cinixys of Bell. 
Although I believe most of these genera to be well founded, 1 cannot refer to 
either of them the two species which 1 have observed in North America. 
Xerobates, Ag. Differs from all other Testudinina in having the front legs 
compressed, without a sign of a plantigrade palm, and large, Hat nails ; the hind 
feet are plantigrade, with a round surface. There are only a few large scales 
side by side upon the forehead. The head is very broad across the temporal 
muscles; the region of the eyes, nose, and mouth is short; and the top of the 
skull nearly horizontal between the eyes. The mouth spreads out widely immedi- 
ately behind the symphysis. The lower jaw is high, and spreads apart from above 
downward. The inner edge of the horizontal alveolar surface of the upper jaw 
descends to a sharp ridge all .around ; from it another ridge reaches across the 
surface at the symphysis to the vertical surface. The ridge which fits into the 
furrow of the lower jaw is very prominent and sharp; it is interrupted at the 
front end only for a short distance. The inner edge of the alveolar surface of 
the lower jaw rises no higher at its front than at its hind end, but is nearly 
horizontal, and nowhere as high as the outer alveolar edge; the ridge thus formed 
is interrupted for only a very short distance at the front end. In the horny 
sheath of the alveolar edge and the inner ridge at the symphysis there is a 
notch, which fits over the opposite ridge of the upper jaw. The oblong, rounded 
plastron is curved upward at the ends. Chap. III. 
GENERA OF TESTUDININA. 
447 
Xerobates Carolines, Ag} This species extends from South Carolina, through 
all the Southern States as far as Texas, in the southern parts of which it is 
replaced by the next species. Its eggs are represented Pl. 7, fig. 28 and 29. I 
am indebted to Dr. Th. S. Savage for interesting observations upon the habits of this 
species. " The domicile of the Gopher consists of an excavation, of a size at the 
mouth just sufficient to admit the animal, and runs in an oblique direction to the 
depth of about four feet. From the entrance it enlarges and expands to a con- 
siderable extent, resembling in its interior outline a vessel of globular shape. Being 
concealed, it is sometimes a dangerous cavity to horsemen at full speed. It is in- 
habited but by one pair. When the dew is on the grass, or it has rained, the 
animal emerges in search of food, which it seems to require daily. It feeds on 
grass and succulent vegetables of various kinds. They eat also the gums that 
exude from trees, especially the inspissated sap of the pine, as seen often at the 
lower part of the stem and exposed roots of that tree. This they will eat also 
in a state of confinement. Their eggs are not laid in their domicile, but in a 
separate cavity near its mouth. The habit of the animal in oviposition, it is said, 
is to draw a circle on the ground about four inches in diameter, and to excavate 
within this to a depth of about the same number of inches, expanding as it 
proceeds, in a manner similar to that adopted in making its domicile. In this 
are deposited five white eggs, of a round form. The number being complete, 
the cavity is filled with earth and pressed down smoothly, and to a level with 
the surface, by the weight of the animal. The time in hatching is said to be 
between three and four weeks. The month in which they lay is June. They 
are long-lived, and attain the size of fourteen to eighteen inches across the cara- 
pace. To capture the Gopher, a deep hole is dug at the mouth of their domi- 
cile, into which they fall as they emerge for food." 
Xerobates berlandieri, Ag. The young is represented Pl. 3, fig. 17-19. It 
has a small yellow dot in the centre of the median and costal scales; the mar- 
ginal scales are only edged with yellow. The sternum, is narrower and more 
projecting in front than that of X. carolinus; in the adult it is even forked. 
Behind it is broader and more turned downward. The centre of the scales 
remains granular for a longer time. The gland of the lower jaw is larger and 
more prominent. This species is smaller than the preceding, and limited to south- 
ern Texas and Mexico. All the specimens that I have seen were forwarded to 
me for examination by the Smithsonian Institution. They were collected by the 
late Mr. Berlandier, a zealous French naturalist, to whom we are indebted for 
much of what we know of the natural history of northern Mexico. 
1 This is the Testudo Carolina of Linnaeus, Testudo Polyphemus of Daudin. 448 
AMERICAN TESTUDINATA. 
Part II. 
Whenever a type of the present period exhibits characteristic features con- 
nected with a circumscribed geographical distribution, it is an interesting problem 
to ascertain whether the fossil representatives of past ages found in the same 
region belong to the same type or not. The existence of North American fossil 
Testudinina during the Tertiary period having been ascertained by Dr. Leidy from 
the beautiful specimens found in Nebraska, I became very anxious to compare 
them with the living Xerobates, which are the only North American Testudinina. 
Professor James Hall, whose collection of fossils, from the Mauvaises Terres, exceeds 
all expectations, has provided me with ample means to make this comparison, and 
I have satisfied myself that they do differ not only from Xerobates, but even from 
all living Testudinina, in combining characters which at present exist only in Emy- 
doids with those that are strictly characteristic of Testudinina. 
For the sake of comparison, I add a few remarks upon the other genera 
which I have been able to examine. 
Chelonoidis, Fitz. The head is narrower across the temporal muscles, and the 
region of the eyes, nose, and mouth longer, than in Xerobates; the top of the 
skull between the eyes descends further forward in this genus. The lower jaw 
is not as high as in Xerobates, but is more rounded at the symphysis, and spreads 
less backward; moreover, it does not here spread apart from above downward, 
but curves out for a little distance below the upper edge, and then turns in to 
the lower edge. The alveolar surface of the upper jaw is raised under the nose 
to a large, round, inverted pit, and has no ridge at the symphysis, but a small 
one on each side of the pit. The ridge around the inner edge of this surface, 
and the one parallel to it, are both small; the latter is tuberculated. The inner 
edge of the alveolar surface of the lower jaw rises higher toward the front end, 
so as to be, for some distance, as high or higher than .the outer alveolar edge; 
this inner ridge is interrupted by a broad depression where the alveolar surface 
rises steeper to fit into the pit above. To this genus belongs the Testudo tabu- 
lata, Auct., of which I have been able to examine a number of living specimens, 
sent to me from Surinam by Mr. C. J. Hering. A close comparison with living 
specimens of Xerobates carolin us shows them to be ent irely different, even gener- 
ically, although Schlegel considers them as identical.1 
Megalochelys, Fitz. This type is closely allied to Chelonoidis; but I have exam- 
ined too few specimens to be able to determine whether it is a distinct genus 
or not. There are some characters which seem to indicate that it is distinct ; 
for example, the inner furrow along the alveolar surface of the upper jaw con- 
tinues deep to its front end, whereas in Chelonoidis it vanishes forward; the 
1 Temm. and Sclil. Fauna japon. p. 70. Chap. III. 
CHELONIAN FAUNAE. 
449a 
ridge on the same surface which fits into the furrow of the lower jaw is sharper 
and more prominent than in Chelonoidis, and is not tuberculated. To this genus 
belongs the large Galapago Turtle, Testudo indica, a living specimen of which 
was sent to me by Mr. Patrick II. Frey, of New York. 
The genera above described may be readily distinguished from Testudo grmca, 
which is the type of the genus Testudo proper. In the latter, the outer furrow 
of the alveolar surface of the upper jaw passes round the front end without inter- 
ruption, and with little change in width ; the ridge which fits into the furrow 
of the lower jaw is very short, being interrupted by a long space in front; the 
inner edge of this surface descends only for a short distance from the hind end 
forward. In the alveolar surface of the lower jaw the furrow and inner ridge 
are very short, and the long, steep surface in front of them turns around the 
end with a broad curve. Cuersus, JlhyZ., is at once distinguished by the mova- 
bility of the posterior lobe of the sternum, but differs also in the scales of the 
legs. It is founded on Testudo marginata. Psammobates, Fitz., is well characterized 
by the small scales which uniformly cover the four plantigrade feet. To it belong 
the well-known Testudo radiata. 
SECTION X. 
CHELONIAN FAUNAE OF NORTH AMERICA. 
The more minutely the geographical distribution of animals is investigated, the 
more do regularity and order appear to exist among them in this respect; so 
much so, that I strongly entertain the hope that naturalists may one day read 
the design which has presided over this arrangement. Owing to the extensive 
contributions I have received for my investigations from every quarter of the 
country, and particularly from the collections of the Smithsonian Institution, which 
contain specimens from the least explored parts of the continent, I have been 
able to trace the natural boundaries of all our Testudinata with a much greater 
degree of accuracy than has hitherto been done. The long lists of localities from 
which I have seen specimens of the different species enumerated in the preceding 
sections, and the names of the observers to whom I am indebted for them, will, 
I trust, afford a satisfactory guarantee for the accuracy of the generalizations derived 
from their study. 
The most striking result of these comparisons is the certainty thus acquired, 
that, while certain genera and species have a very wide range, others are circum- 450b 
AMERICAN TESTUDINATA. 
Part II. 
scribed within as narrow limits as any other type of animals. It has already been 
stated, (p. 301,) that there is a great difference between the geographical distribution 
of the Sea Turtles and that of the fluviatile and terrestrial species of this order. 
There are, in fact, only two marine Faunae of Testudinata, - that of the Atlantic 
Ocean, and that of the Pacific, including the Indian Ocean; and between the two 
there exist only specific differences between their representatives, the genera are 
the same. In the Atlantic Faunae we have four species along the American coasts: 
Sphargis coriacea, Thalassochelys Caouana, Chelonia Mydas, and Eretmochelys imbri- 
cata; while in the Pacific Fauna only one species, the Chelonia virgata, has thus 
far been noticed along the western coast of America. 
Among the fresh-water species there are two, Chelydra serpentina and Ozotheca 
odorata, which extend nearly over the whole range occupied by Testudinata, east 
of the Rocky Mountains. Thyrosternum pennsylvanicum is also very widely dis- 
tributed ; and so is Malacoclemmys palustris; but this last occurs only in salt-marshes 
along the sea-shores from New York to Central America. All the other species 
have a more or less circumscribed home; so that the whole country may be divided 
into a number of very natural Chelonian Faunae, according to their distribution. 
1st. The North-eastern Fauna. It extends as far north and east as Turtles occur, 
that is, through parts of Nova Scotia, New Brunswick, and Canada West, a little 
beyond the forty-fifth isotherm. Westward it reaches Lake Erie, and southward 
North Carolina, extending along the Alleghanies even as far south as Georgia. Its 
boundaries coincide with those of Chrysemys picta. It is chiefly characterized by 
Clemmydoidae, three distinct genera of which occur within its area: Nanemys 
guttata, which, like Ch. picta, ranges through its whole extent, with the exception 
only of its most north-eastern parts; Glyptemys insculpta, which is found from the 
most northern to the middle regions of the Fauna; and Calemys Miihlenbergii, which 
occurs only in the middle region. Ptychemys rugosa is characteristic of the borders 
of the Chesapeake Bay. Cistudo virginea is found everywhere, but sparingly in 
the northern range; while it extends very far westward and southward, where it is 
most common. Chelydra serpentina and Ozotheca odorata also occur everywhere, 
while Thyrosternum pennsylvanicum begins to appear in its middle tracts only. 
Along the sea-shores, Malacoclemmys palustris begins also in the middle region of 
the Fauna; but it is nowhere found in the interior, far from salt water. Emys 
Meleagris, which is characteristic of the north-western Fauna, is rare here, and so 
also is Graptemys geographica. On the western borders of this Fauna, Aspidonectes 
spinifer begins to make its appearance; but there is no trace anywhere of the 
family of Testudinina. 
2d. The Western Fauna. This Fauna extends westward from the western parts 
of Pennsylvania to the arid plains at the foot of the eastern slope of the Rocky Chap. III. 
CHELONIAN FAUNAL 
451c 
Mountains, beyond which Turtles do not occur. Its northern limit is as high as 
the junction of the Yellowstone and the Missouri, but does not touch the shores 
of Lake Superior. Its southern limits extend to Tennessee, Arkansas, and Kansas. 
The most characteristic species of this Fauna are Amyda mutica, Aspidonectes spinifer 
and nuchalis, Chrysemys marginata, Bellii and Nuttalii (oregonensis), Graptemys geo- 
graphica and LeSueurii, Trachemys Troostii and elegans, and Emys Meleagris. Ch. 
marginata is limited to the region of the lakes; but Ch. Bellii extends to the junc- 
tion of the Missouri and Mississippi, while Ch. Nuttalii extends to the Upper Missouri. 
Strange to say, Aspidonectes spinifer is among the species found furthest to the 
north; but Asp. nuchalis takes its place in Tennessee. Emys Meleagris is most 
common in the region of the great lakes. Cistudo virginea extends as far west 
as the great lakes, and is replaced by Cistudo ornata further west and north. 
Chelydra serpentina and Ozotheca odorata range as far west as any other Testudi- 
nata, though the latter does not extend so far in a north-westerly direction as 
Chelydra; this is also the case with Thyrosternum pennsylvanicum. Ozotheca 
tristycha and Ptychemys hieroglyphica occur in the more southern parts. There 
is something extraordinary in the distribution of Trachemys elegans, as it ranges 
from the upper Missouri to the lower Rio Grande, while Trachemys Troostii occupies 
only the middle and more southern parts of the western Fauna. Graptemys Le- 
Sueurii is also found in a north-southerly direction, while Gr. geographica extends 
from east to west in the more northern parts. The Testudinina are as completely 
foreign to this Fauna as to the north-eastern. 
3d. The Southern Fauna. Its boundaries are easily traced. Beginning on the 
Atlantic coast in the southern parts of North Carolina, it extends through South 
Carolina, Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana, and northern 
Texas. These limits coincide with the range of Ptychemys concinna and of Deiro- 
chelys reticulata, and nearly also with that of Platypeltis ferox and Xerobates 
carolinus, only that the two latter do not extend to North Carolina; Platypeltis 
ferox does not even extend beyond Georgia. However, the most striking types 
of this Fauna are Xerobates carolinus and Gypochelys lacertina. Besides Platypeltis, 
another Trionychid, Aspidonectes asper, occurs in this latitude, but only in the more 
westerly part of the Fauna, within which Goniochelys triquetra and Chrysemys 
dorsalis are also limited; whilst Trachemys scabra is only found on the Atlantic 
side of Georgia and in the Carolinas. Ptychemys mobiliensis occurs only in the 
States bordering on the Gulf of Mexico. Ozotheca odorata and Thyrosternum 
pennsylvanicum belong also to the southern Fauna; and so does Chelydra serpentina, 
unless the southern Chelydra be a distinct species. (Comp. p. 417, note 2.) The 
same may be said of Cistudo virginea, unless C. triunguis and major are also distinct 
species. Malacoclemmys palustris is found everywhere along the sea-coast. 452d 
AMERICAN TESTUDINATA.' 
Part II. 
4th. The Mexican Fauna. I have to mention this Fauna on account of its exten- 
sion into the boundaries of the United States. Among its characteristic Testudi- 
nata found along the Rio Grande, the most remarkable are Xerobates Berlandieri 
and Aspidonectes Emoryi. Platythyra flavescens extends further north, even as far 
as Arkansas, while Thyrosternum sonoriense occurs further west, in Sonora. The 
Turtles of Cuba, as far as I know them, differ specifically from those of this and 
the preceding Fauna. 
5th. The Californian Fauna has a wide range from north to south, beginning 
at the straits of Juan de Fuca and extending to the Gulf of California, and yet over 
this whole extent of country only a single Turtle is found, Actinemys marmorata; 
for it is not true, that the Galapago Turtle occurs also in California in a wild 
state; and the existence of a distinct species of Cinosternum on that side of our 
continent appears very doubtful to me. (Comp. p. 429.) 
There is a very striking resemblance with what obtains in Europe in this 
scarcity of Testudinata in California, contrasted with their extraordinary diversity 
and great number on the eastern side of the continent. This, again, recalls their 
profusion in eastern Asia; so that, even with reference to the special geographical 
distribution of the Testudinata, the great laws that obtain with regard to the simi- 
larity and differences of the continents are fully confirmed. 
After what has just been stated, it is hardly necessary to call especial atten- 
tion to the fact, that, upon a map representing the geographical distribution of 
the Testudinata in North America, the whole table-land between the Sierra Nevada 
of California and the Rocky Mountains, as well as the eastern slope of the latter, 
down to the Great American Desert, would be left entirely blank, not a single 
species of Turtles extending over any part of this extensive tract of land. It would 
be a mistake, however, to infer, from this fact, that these animals are excluded from 
mountainous regions. In the range of the Alleghanies there are many species, which 
ascend to the height of several thousand feet, and among those that reach the 
greatest heights are Cistudo virginea, Chelydra serpentina, and a species of Aspido- 
nectes, probably Asp. nuchalis (comp. p. 406); but 1 regret that 1 am unable to 
give the absolute height with any degree of accuracy.