THE 
OSTEOLOGY 
OF 
VULPES MACROTIS 
BY 
Dr. R. W. SHUFELDT. 
FROM THE JOURNAL OF THE ACADEMY OF NATURAL SCIENCES OF 
PHILADELPHIA, VOLUME XI, PART 3, AUGUST, 1900. 
PHILADELPHIA : 
P. C. STOCKHAUSEN, 
53-55 N. 7th St., 
1900. THE 
OSTEOLOGY 
OF 
VULPES MACROTIS 
BY 
Dr. R. W. SHUFELDT. 
FROM THE JOURNAL OF THE ACADEMY OF NATURAL SCIENCES OF 
PHILADELPHIA, VOLUME XI, PART 3, AUGUST, 1900. 
PHILADELPHIA : 
P. C. STOCKHAUSEN, 
53-55 N. 7th St., 
1900. THE OSTEOLOGY OF VULPES MACROTIS. 
Dr. R. W. Shufeldt. 
As long ago as October, 1887, there was collected for me at Fort Mojave, 
Arizona, U. S. A., the skeleton of one of the smaller foxes of the southwestern 
part of the United States. It was from an adult male individual, and was taken 
by Private Charles Ruby, of Company A, of the 9th U. S. Infantry, who, through 
Professor S. F. Baird’s assistance, had long collected material in the West for the 
Smithsonian Institution at Washington, D. C. The specimen was sent to me when 
I was serving at Fort Wingate, New Mexico, as post surgeon. Upon examination 
the skeleton was found to lack but one patella, a tooth, the clavicles, part of the 
hyoidean arch, and the os penis. It was labelled Vulpes velox. 
In April, 1900, this material was still in my private collection, and upon 
looking into the subject, it seemed to me that the skeleton in none of the smaller 
western foxes had ever been fully described. On Plate XXXIV, in Baird’s Mam- 
mals of North America, there are three views given of a skull of Vulpes velox 
with two of the mandible. These are quite accurate, as they were carefully com- 
pared by me with a good average skull of that species. Mivart gives the dental 
formula of V. velox in his well-known work on the Canidse, and Professor Huxley 
had a skull of this fox at hand at the time he wrote his valuable paper On the 
Cranial and Dental Characters of the Canidcei As this species was known to Say, 
and to Audubon and Bachman, it is very likely that reference has been made to it 
many times since their day, but there seems to be no complete account of its skeleton 
extant or of that of any of its near congeners or allies in the southwest. 
Very recently this skeleton was kindly examined for me by Mr. Gerrit S. 
Miller, Jr., of the Department of Mammals of the United States National Museum, 
and carefully compared with such material as was necessary representing the 
osteology of the genus Vulpes in the collections of that institution. Mr. Miller 
quickly made it clear that the skeleton in my possession had belonged to an indi- 
vidual of the species known as Vulpes macrotis, a form closely allied to V. velox, 
and not to the latter form, from which it was easily distinguished by a number of 
very good characters, both osteological and otherwise. This well-known mamma- 
logist was also good enough to loan me an example of the skull and mandible of 
V. velox, belonging to the United States National Museum, for use in the way 
of comparison in the present account. This skull was from a specimen collected 
by the late Doctor Elliott Coues on the Souris River, Dakota, and was a male 
1 P. Z. S., April 6, 1880. 396 
THE OSTEOLOGY OF VULPES MACROTIS 
animal.2 At this time the National Museum does not possess a skeleton of 
either V. velox or V. macrotis, although there are skeletons of other foxes in the 
collections. 
It is not the object of the present memoir to enter in detail into the subject of 
the position of the Canidge in the system, much less to make an exhaustive com- 
parison of the skeletons of the genus Vulpes, although that would be an excellent 
task to accomplish. Unfortunately the material is not at hand at the present 
writing to carry out either of these projects, so the best that can be done at this 
writing is to offer as complete an account of the skeleton of Vulpes macrotis as 
possible; then naturalists in the future, better supplied with material, will be able 
to utilize this contribution in their researches. 
Flower, in his Osteology of the Mam?nalia, has truly said that a “ perfect 
arrangement of any group of animals can only be attained simultaneously 
with a perfect knowledge of their structure and life-history. We are still so far 
from this that any classification now advanced must be regarded as provisional, and 
merely representing our present state of knowledge. Moreover, as naturalists will 
estimate differently the importance to be attached to different structural modifica- 
tions as indicative of affinity, it must be long before there will be any general 
agreement upon this subject.” It is now about twenty years ago since Professor 
Flower penned those words, and they are quite as true to-day as the day he wrote 
them. Several years afterwards, in his masterly contribution to the ninth edition 
of the Encyclopaedia Britannica, on the Mammalia, he recognizes a Section 
Cynoidea of the Carnivora, in which the single family Canidge is placed, to contain 
all of the “ dog-like animals,” they holding, as this eminent authority seemed to 
think, “ an intermediate position between the other two sections (iEluroidea and 
Arctoidea), retaining also many of the more generalized characters of the ancient 
members of the order. The structure of the auditory bulla and adjacent parts of 
the bones of the skull is quite intermediate between that of the iEluroid and 
Arctoid forms. In the number and arrangement of the teeth they more nearly 
approach the primitive heterodont type than any other existing Carnivora.” 
Flower divided the family Canidge into two series, with several genera in each, 
—thus : 
Family. 
Series. 
r L 
Genera. 
Canis. 
2. 
Cyon. 
A.—Thooid or Lupine Series. 
* 
3. 
Lycalopex. 
4. 
Nyctereutes. 
CANIDiE. 
L 5. 
ICTICYON. 
r 6- 
VULPES. 
B.—Alopecoid or Vulpine Series. 
7 
Fexnecus. 
8: 
Lycaon, 
l 9. 
Otocyon. 
It was Professor Huxley, in his memoir On the Dental Characters of the 
2 No. 15,355, Coll. U. S. Nat. Mus. THE OSTEOLOGY OF VULPES MACROTIS. 
397 
Canidce,3 who first established or distinguished these two series of the Canid®, 
and in doing so he admitted that “ within each of these series there are consider- 
able modifications, which give rise to corresponding terms in the two series.” It 
appears that the first of these modifications is in the proportion of the sectorial 
and next following teeth relatively to the basicranial axis, which axis is taken at 
the value of 100, and is a line, measured mesiad on the base of the skull (bisected) 
extending from the posterior border of the basioccipital bone to the articulation 
between the presphenoid and the ethmoid. It is evident, as Professor Pluxley adds, 
that the “ measurements of the other parts of the skull can then be expressed in 
terms of 100, and their development, irrespectively of the absolute size of the 
animal, becomes apparent.” 
The second modification noticed refers to the extent of the areas for the 
insertion of the temporal muscle upon either side of the skull. Huxley observed 
that “ in all young canine animals,' the upper edges of the attachment of the 
temporal muscles are separated by a wide interspace of a lyrate form, with its 
apex directed posteriorly, which may be called the sagittal area. The boundaries 
of this area are but little raised; and, as age advances, it becomes gradually 
diminished by the approximation of the temporal muscles. This approximation 
takes place more rapidly behind than in front, and results in the narrowing, and 
in most cases coalescence, of the temporal ridges throughout the greater part of 
the length of the sagittal suture, while in front they diverge to the supra-orbital 
processes and inclose the glabellar area.’' This very distinctive feature is well 
seen in the skulls I have at hand, for in Vulpes velox and V. macrotis, the sagittal 
area, though unlike in form in both, is large and distinctly defined, while in all 
the skulls of a series of Cam's latrans, collected by me in New Mexico and Arizona, 
this area is reduced to a median ridge of narrow width, and extending as far for- 
ward as the coronal or fronto-parietal suture. This ridge is longitudinally marked 
in the median line by the sagittal suture for the anterior two-thirds of its length. 
In speaking of a third modification, Huxley remarked that “ In most of the 
Alopecoids, the contour of the inferior margin of the angular process continues the 
direction of that of the inferior margin of the ramus in front of it; and this slopes 
gradually upward and backward. In C. littoralis and C. cinero-argentatus, 
however, the inferior contour of the ramus in the region of the attachment of the 
digastric muscle, in front of the angular process, is inclined almost at right angles 
to the latter, and forms a sort of rounded ‘ subangular lobe ’ beneath the angular 
process. De Blainville long since figured and called attention to this feature of the 
mandible in C. cinero-argentatusC The angular processes, as well as the sub- 
angular lobes, are characteristically the same in Vulpes velox, V. macrotis and in 
C. latrans. They quite closely agree with what Professor Huxley found in C. 
fulvipes. Further on in the present paper reference will again be made to some 
of the data set forth in this excellent memoir. 
3 P. Z. S., 1880, p. 248. 398 
THE OSTEOLOGY OF VULPES MACROTIS. 
The Skull. 
Both the skull (Plate XXII, tigs. 1-7) of Vulpes maci'otis as well as that of 
V. velox before me, belonged to individuals that had not fully reached maturity. 
This is clearly proven by the fact that both the cranial and the facial sutures are 
still very evident and easily traced. This is also the case with one of my skulls 
of Canis latrans, while in another skull of the same species the sutures are all 
nearly obliterated, while other evidences of advanced age are present. These 
changes are well known to students of mammalian osteology, and are sometimes 
very remarkably exemplified: the skulls in extremely old individuals varying 
widely in their external appearances from those of subadult specimens of the same 
species, and to an extent to sometimes almost lead to the belief that the animals to 
which they severally belonged were not of the same species. This is a fact that 
paleontologists bear well in mind, and there are instances upon record where mis- 
takes, due to the non-appreciation of these changes, have occurred.4 The manner 
in which they effect the appearance or morphology of the temporal fossae and 
sagittal crest in the Canidae has already been noticed above, and it remains but to 
say that during their progress there is no appreciable change either in form or 
appearance of the brain-case within. These changes occur in many mammals, and 
are particularly noticeable in the elephant. 
Viewed upon its superior surface it will be seen that the cranium of Vulpes 
velox has a subglobular form with the temporal areas slightly roughened, and the 
extensive shield-shaped sagittal area quite smooth. The apex of the latter is 
towards the interparietal bone, and the sagittal crest is barely perceptible, even 
posteriorily, where in Canis latrans it is very conspicuous. In both Vulpes ma- 
crotis and V. velox the coronal suture and the joosterior two thirds of the sagittal 
exhibit interlocking serrations of the apposed margins, a condition that likewise 
obtains in the frontal suture of the skull of V. velox. 
All the other sutures upon this aspect of the skull in these two foxes, as well 
as in the coyote, have smooth margins, especially the nasal and inter-nasal ones. 
Either post-orbital process is well developed, being a triangular ledge of bone, with 
its apex directed backward and outward, and its superior surface showing a 
decided depression, better marked in macrotis than in velox, while in Canis latrans 
it is not present at all, that surface being rounded, and the process, bluntly pyra- 
midal in form, extending directly outward. Proportionately, the skull in V. 
macrotis is longer and narrower than it is in V. velox, and this is well seen in its 
facial portion on the surface we are now considering, where in the first-named fox 
this feature is markedly the case. 
* In this connection Flower has said that these changes or modifications “depend mainly on the 
fact that the brain, and consequently the cavity which contains it, and also the sense capsules, increase 
in size in a much smaller ratio than the external parts of the head, especially the jaws and prominences 
for the attachment of muscles. The disproportionate growth and alteration of form of these parts, 
concomitant with little or no change in the brain-case, is effected partly by increase in thickness of the 
bones, but mainly by the expansion of their walls and the development of cells within, which greatly 
extend the outer surface without adding to the weight of the bone.”—Osteology of the Mammalia, 3d 
Ed., p. 148. THE OSTEOLOGY OF VULPES MACROTIS. 
399 
The zygomatic arches are prominently developed in these animals, and possess 
the same general characteristics in both species. Their extremities, composed of 
the usual bones, face directly upward, or, in other words, they have a superior and 
an inferior surface, the zygomatic or squamosal end being triangular and small, 
while the malar-maxillary extremity is also triangular, but broad and extensive. 
The middle third of the arch possesses an internal and external surface, the superior 
and inferior margins being somewhat sharp and curved,—the upper one convex 
and the lower concave, Plate XXII, fig. 1. 
In Vnlpes macrotis the fangs or roots of the last molar tooth (m2) upon either 
side perforate anteriorly the zygomatic arch. These perforations occur just within 
the postero-mesial borders of the expanded portion, there formed by the maxillary 
bone, Plate XXII, fig. 7. Similarly perforations also occur in Vulpes velox and in 
C. latrans. Viewing the skull directly from above, the post-orbital processes shut 
these molar foramina out of sight in the majority of skulls, but they are sometimes 
seen upon this aspect in macrotis, because it has such a narrow skull and flaring 
zygomatic arches. 
As in the Canidas generally, either nasal is a long, narrow bone, which, with 
the fellow of the opposite side, extends from a point opposite the anterior margin 
of the orbit to the supero-mesial boundary of the anterior nares. Here the border 
of either bone is notched and free, the two together completing about a fourth of 
the narial aperature. In Canis latrans their anterior extremities are truncated 
from their antero-external angles backward obliquely to their postero-mesial angles. 
Their hinder ends in Vulpes macrotis articulate with the frontals and are likewise 
truncated, the two bones together forming a wedge, entering between the frontals, 
its apex being situated posteriorly. The external border of a nasal articulates with 
the corresponding borders of the frontal, maxillary and premaxillary of the same 
side. In this situation the nasal process of the frontal tends to extend forward to 
have its anterior apex meet the apex of the nasal process of the premaxillary. 
Between these two species, however, a greater or less interval occurs, greater 
in velox than in macrotis, while in some of the Canidre (as figured by Huxley) they 
seem actually to meet. It is certainly the case in Canis littoralis, and may occur 
in Canis vulpes. Foxes and other forms in the family with shorter faces may have 
the apices of these processes well apart. There is a very considerable interval, 
for example, in Odocyon lalandii. Upon the posterior aspect of the skull of Vulpes 
macrotis it is to be observed that in the median line above is the well-developed 
inter-parietal bone, with its contracted anterior angulation extending forward 
between the parietals, with its similar and lateral projections lying, on either hand, 
between the corresponding parietal and supraoccipital. Its mid-longitudinal line is 
co-extensive with the comparatively feebly developed sagittal crest; the low but 
well-defined occipital crest traverses from side to side its lateral projections. The 
parietal sutures of the interparietal long remain visible or even ununited, while the 
bone seems to early ankylose with the supraoccipital. This is also the case in other 
Canidm and in many domesticated dogs. As in all true foxes the supraoccipital 400 
THE OSTEOLOGY OF VULPES MACROTIS. 
is comparatively large and broad, with its internal and external surfaces quite 
smooth. For the most part it lies in the vertical plane, being perpendicular to the 
basi-cranial plane. 
Vulpes macroiis possesses a very large fora)nen magnum, a trifle larger in 
proportion than it is in V. velox, and very distinctly so in comparison with that 
foramen in C. latrans. For example, the transverse or major axis of the subellip- 
tical foramen magnum in V. macrotis measures 1.3 centimeters, its minor vertical 
axis 1.1 cm. and the mid-longitudinal axis of the skull, from the border of the 
foramen magnum to the most anterior point between the premaxillaries, measures 
10.2 cms. In C. latrans the corresponding measurements are 1.8 x 1.4 cms., and 
18.5 cms. The occipital condyles have their narrow and mesial moieties in the 
horizontal plane where they are but barely separated in the middle line. Their 
broader and more rounded halves curl upward, one upon either hand, and their 
anterior borders are markedly concaved, being correspondingly convex behind. 
As in the Canidae generally the paroccipital processes are conspicuously 
developed. Either one, as a strong projection, descends and completely molds 
itself upon the superior and posterior aspect of the corresponding auditory bulla, 
lending to it considerable support. Between either par-occipital process and the 
occipital condyle of the same side, there is a narrow though deep valley, while to 
the outer side of the process, upon this aspect of the skull, may distinctly be seen 
the mastoid portion of the periotic bone. It is bounded in front by the low, thin, 
sharp line of the lambdoid or occipital crest. 
Turning to the lateral aspect of the skull in V. macrotis, Plate XXII, fig. 1, 
the long, narrow face that this fox possesses at once becomes apparent. The 
lengthy and aoute backward projecting naso-maxillary process of the premaxillary 
is distinctly seen, as is the sutural line between the maxillary and frontal and malar 
bones. It is tangent to the periphery of the orbit in front, and passes beneath it, 
below. Forward of this, and above the diastema existing between the third pre- 
molar and sectorial teeth, is the large and vertical slit-like infraorbital foramen, 
for the passage of the second division of the fifth nerve. Within the orbit may be 
seen the usual foramina and the usual bones forming its smooth, shallow, antero- 
mesial concavity. The upper half of this is formed by the orbital portion of the 
frontal; anteriorly by the small lacrymal; below by the pterygoid and maxillary; 
externally by the malar; and postero-mesially by the palatine, orbito-spenoid and 
the alisphenoid. The various foramina require no special description, as they 
make no particular departure from those openings as they occur in the skull of the 
common dog. A description of the zygomatic arch has already been given in a 
previous paragraph. 
In Vulpes macrotis the meatus auditorius externus, is somewhat larger, in 
comparison, than in V. velox; very much more so than in C. latrans. Indeed, 
the opening is so large in the specimen at hand that the interior of the tympanic 
cavity can easily be studied from without. The ossicula auditus (malleus, incus 
and stapes) all appear to be lost, and so cannot at this writing be described. THE OSTEOLOGY OF VULPES MACROTIS. 
401 
Firm osseous union has solidly sealed together the various bones bounding the 
auditory chamber, as the periotic, the squamosal (above), the tympanic, and the 
auditory bulla (beneath), while to the inner side we see the basi- and exoccipital. 
The sutures among the squamosal, parietal, alisphenoid, and frontal bones upon 
the lateral aspect of the skull, remain clearly defined for the greater part of the 
animal’s life, and it is only in Canidae of extreme old age that they become to some 
degree faintly defined or almost obliterated. 
Passing to the consideration of the base of the skull in Vulpes macrotis it is 
interesting in the first place to note the extent of difference existing between it and 
a skull of V. velox seen upon the same view, PI. XXII, figs. 5 and 6. Upon 
examination of material in the United States National Museum it would appear 
that these differences are constant and diagnostic. Principally, there are three of 
them that are evident upon casual observation :—In V. macrotis the osseous palate 
is transversely much narrower than in V. velox. This is especially noticeable 
in the distance between the carnassial and first molar teeth of the opposite sides. 
The malar portion of the zygomatic arch is deeper in the antero-posterior direction 
in macrotis than in velox. The auditory bullce are comparatively larger in the 
first-named fox than in the last-named. This character is very evident when we 
come to compare series of skulls of these two well-marked species. In general the 
entire skull of V. macrotis is thinner and more delicately fashioned than in velox, 
and its being narrower throughout is easily appreciated upon comparison, either 
from a dorsal or ventral aspect, PL XXII, figs. 2, 5, 6 and 7. 
In the bony roof of the mouth in the specimen of V. macrotis at hand, the 
sutures defining the limits of the premaxillary, maxillary and palatine bones have 
become almost entirely obliterated. This is not usual in other Canid®, unless age' 
has very far advanced. We know, however, that in this family the suture between 
the maxillaries and premaxillaries in this situation is a transverse one, extending 
from a mid-point upon one canine tooth to pass directly across to the one upon the 
other side,—the two, long, slit-like anterior palatine foramina lying partly upon 
the maxillary side of the boundary, PI. XXII, fig. 5. Otherwise, upon either side, 
the maxillary supports the dental armature of the upper jaw in this, as in other 
true foxes, namely, the four premolars, and the two true molars, each premaxillary 
supporting three inciser teeth. Posteriorly, the free margins of the palatines are 
rounded, forming, as they do, the anterior border of the posterior narial aperature. 
Upon either side, the palatine bones are continued backward by the thin and com- 
pressed pterygoid bones, which here, as vertical plates, descend directly downward 
from the alisphenoids, terminating below in free lamin® of bone, each known as the • 
hamular process of the pterygoid. Each is represented by a thin triangular plate 
of bone in a vertical longitudinal plane, separated by an interval of nearly a centi- 
meter in width. The valley thus created is deep and of some length (2 eras.), it 
being the backward extension of the narial passage, and forms in the Canid® a 
conspicuous feature of the mid-basal area of the skull. Above, either pterygoid 
articulates with the under surface of the presphenoid and the basi-sphenoid bones. 
51 JOURX. A. N. S. PHILA., VOL. XI. 402 
TIIE OSTEOLOGY OF VULPES MACROTIS. 
In the middle line of the base of this skull of V. macrotis, proceeding from 
before backwards, we are enabled to see the vomer, the presphenoid and the basi- 
sphenoid, and the sutures among them are fairly well defined. Still more posteriorly 
the basi-occipital creates the roof of the narrow, but deep passage between the 
auditory bullce, and its lateral margins are raised that they may better articulate 
with those remarkable osseous capsules upon either side. Upon examining the 
aperature of the Eustachian canal, the foramen lacerum medium, the foramen ovale, 
foramen rotundum, the alisphenoid canal, the postglenoid foramen, the foramen 
lacerum posterius, the condylar foramen, the stylomastoid foramen, and some few 
other features in this region of the base of the skull, they are seen to agree with 
what is already known as to the cranial osteology of this family of mammals. 
The glenoid fossae are narrow and elongated; their long axes being perpen- 
dicular to the longitudinal axis of the skull. Behind either one is a conspicuous 
post-glenoid process, curving downward and forward, and serving to retain the 
condyles of the mandible in their sockets during life. Either auditory bulla is 
hemi-ellipsoidal in form,—thin and hollow. The exposed convex surface is ex- 
tremely smooth, though in some species of the Canidae it may be slightly roughened 
by delicate venations, but these are absent in the genus Vulpes. Within the 
cranial casket a well-defined sella turcica is seen, and upon either hand, the internal 
surfaces of the orbito-sphenoid bones. Anteriorly, the posterior margin of the 
mesethmoid is inserted, forming, as usual, the crista galli. The cribriform plate is 
extensive, and presents two suboval moieties with the posterior surfaces facing 
backward and very slightly, upward. Internally, this plate is perfectly smooth, 
and the foraminal perforations exceedingly numerous. 
As is the case in Canis latrans. and other Canidm, the dense inner surface of 
the vault of the cranium is marked by convolutions, to receive the correspond- 
ing convolutions of the brain-mass, while the tentorium cerebelli very extensively 
ossifies. All the fossae of the brain-case—cerebellar, cerebral, and olfactory— 
are well marked otf, and comparatively capacious. Other features of the interior of 
the brain-case are present, but being well known require no special description 
here. 
The spongy bones of V. macrotis were not studied in section, but they are 
probably as complicated as in C. latrans, of which such a sectional preparation 
was examined. 
That they are so in many of the domesticated dogs has been clearly shown by 
the late Sir William Henry Flower.5 
These turbinal masses of bone in the olfactory chamber of the skull in mam- 
mals are worthy throughout the class of our very closest study. Morphologically 
they are full of interest, and should never be set aside as was the habit of the late 
Dr. Elliott Coues, who thought them too complicated to be worthy of description. 
Such an unscientific opinion was fully controverted by the late keen anatomist, Dr. 
Harrison Allen, who devoted an entire memoir to the comparative morphology 
0 Osteology of the Mammalia, pp. 129, 130. THE OSTEOLOGY OF VULPES MACBOTIS. 
403 
of these ossifications in many of the mammalia. They appear to be of certain 
taxonomic value among the bats. 
The hyoidean apparatus, in so far as its osseous parts are concerned, is not 
complete in this skeleton, some of the delicate bones having been lost. There 
is every indication, however, that it in no way markedly departs from the cor- 
responding structures in other small foxes, and in the main with the Canidae 
generally. Professor Flower gives an excellent account of the hyoidean apparatus 
of the dog in his Osteology, and I have studied these visceral arches in both 
adult and embryonic types among the mammalia. They are more or less uniform 
for the family, and among the Canidae, if my information be correct, present 
hardly any generic differences. The mandible has the general form of that bone 
in the family Canidae (PI. XXII, figs. 1, 3 and 4), it being Y-shaped in form, 
and ankylosed quite firmly anteriorly by an extensive symphysis. By active 
maceration, however, the two elongated rami will separate at this point, as has been 
the case in jaws of the coyote and kit fox at hand. According to some authorities, 
in very old animals the union may become complete and firm through cobssification. 
In V. velox a ramus of the mandible is shorter, deeper, and thicker through and 
through than it is in V. macrotis, in which latter fox it is evidently more delicately 
fashioned. Either ramus has an extreme length of about 7.9 cms., its lower margin 
being thickened and rounded, convex in the antero-posterior direction, and very 
slightly curved from side to side. Its upper border exhibits the sockets for the 
implantation of the mandibular teeth, six much smaller ones occurring anteriorly 
on the united rami for the incisors. The symphysis has a length of about 2.3 cms., 
it being more extensive in front and tapering off behind. Between a canine socket 
and the coronoidal vertical portion of the jaw, the alveolar border is quite straight, 
while nearly a level surface exists anteriorly and above the symphysis bounded by 
the sockets of the first premolars, the canines and the incisors. The condyles stand 
out quite prominently, being transversely elongated, narrow and attached by their 
mid-anterior points at right angles to the plane of either coronoidal portion of the 
jaw, at points about half way between the apices of the coronoidprocesses and the 
angles, or about in the same plane in which the alveolar borders lie. The coronoid 
process upon either side is flat and smooth on its mesial surface, and concaved 
throughout upon its external aspect. It is, on the whole, moderately recurved 
backward, the true apex being pointed in that direction. Its anterior border, ex- 
ternally, is thickened and there forms a narrow though conspicuous rim. At either 
angle there is a prominent angular process developed, which is present in the jaws 
of all of the Canidae examined by me. Anything approaching a subangular lobe, 
however, is quite absent,—in which character, strange to say, it agrees with Icticyon 
venaticus, but not with Otocyon lalandii (where this lobe is much produced), nor 
with Canis azarce and C. littoralis. On the mesial aspect of either ramus below 
and between the condyle and the posterior commencement of the alveolar border, 
we meet with the inferior dental foramen, it being of some considerable size, and 
opens directly backward. 404 
THE OSTEOLOGY OF VULPES MACROTIS. 
On the external surface of either ramus in front there are to be seen two more 
foramina,—the anterior one is the mental foramen, and is at a point below the 
diastema between the first and second premolars; the other, behind it, smaller in 
size, is slightly in front of the corresponding interval between the second and third 
premolars. In C. latrans they are nearly of a size, and the posterior one is im- 
mediately below the centre of the third premolar. In all instances these foramina 
are in the same horizontal plane and midway between the alveolar and lower border 
of the ramus. Viewing the ascending portion of either ramus from behind, it will 
be seen that it curves gently outward, which is the case in alt of the Canidae. 
Professor Huxley made some interesting comparisons of this aspect of the 
mandible among groups more or less remotely or nearly allied to the canine group.6 
The Axial Skeleton. 
Vulpes macrotis may be said to have a somewhat delicate frame constituting 
the skeleton of its trunk. The cervical, dorsal and lumbar vertebras all possess 
thin, sharpened and produced processes, thus doing away with all appearance of 
heaviness in structure or bulkiness in form, as we notice in some small mammals. 
The caudal vertebras again are slender and elongated, making the skeleton of the 
tail appear lash-like and frail. Much lateral compression characterizes the skeleton 
of the thorax, the ribs being long and not at all stout, while the sternum has a 
corresponding structure, the segments composing it being small, elongated, and 
more or less slender. For the size of the animal, the pelvis is rather a stout bone, 
but at the same time by no means strikingly so. In the number of vertebra 
possessed by Vulpes macrotis, or in the specimen now being examined by me, it 
agrees exactly with a specimen examined by Sir Wm. Henry Flower of Canis 
vulpes ; in other words, it has seven cervicals, thirteen seven lumbar, three 
sacrals, and twenty-one caudal vertebrae. Professor Flower met with a specimen of 
Canis lagopus that had the same number in the various divisions of the vertebral 
chain, while in another case of Canis vulpes the animal had but nineteen caudal 
vertebrae. All of the ferine forms of the Canidae, so far as we know, possess seven 
cervicals and three sacrals. Variation sometimes takes place in the domesticated 
breeds of dogs in the lumbar and sacral regions, as Flower found a German boar- 
hound with fourteen thoracic or dorsal vertebrae; Newfoundlands and mastitis with 
eight lumbar vertebrae ; and a greyhound with four sacrals. Canis procynoides has 
fourteen thoracic and but six lumbar vertebrae, and C. vulpes has been known to 
have the same number. Otocyon megalotis has the usual number in the series, but 
has twenty-two vertebrae in the skeleton of its tail. It is this caudal part of the 
vertebral column that varies most in this particular. Omitting the domesticated 
breeds of dogs, however, it probably can be said with truth for the Canidae that the 
number of caudal vertebrae are never less than fourteen fcticyon venaticus) nor 
more than twenty-two, which is the case, as has just been noted, in Otocyon 
megalotis. 
fi P. Z. s., 1880, p. 263, fig. 14. THE OSTEOLOGY OF VULVES MACROTIS. 
405 
The atlas is the broadest bone of the entire column, though the spreading 
transverse processes of the last lumbar gives it nearly an equal breadth. No 
vertebra in the entire chain at all resembles the atlas in form. It is about twice 
as wide as it is long, and its big neural canal is bounded on either side by the 
narrow cap-like articulations for the condyles of the occiput. Either quadrate, 
horizontal transverse process is pierced, near its middle, by the vertebrarterial canal, 
the foramen for the first spinal nerve being anterior to this just within the supero- 
anterior border close to the condyloid cup. A rudimentary liypapophysis exists, 
but the neural spine is entirely absent. There is a smooth articular facet present 
for the articulation of the long, peg-like odontoidal apophysis of the axis. It is 
situated in the middle line inferiorly within the neural canal. The thin, sharp, 
lofty neural spine of the axis extends the entire length of that bone, and projects 
conspicuously beyond the centrum in front. The haemal spine is likewise laterally 
compressed, but it is feebly developed and principally confined to the hinder part 
of the centrum of the vertebra. This is likewise the case with the third, fourth 
and fifth cervicals, this inferior spine being absent upon the sixth and seventh 
cervicals, as it is completely so from the balance of the vertebral column. Neural 
spines, however, are found upon the last five cervicals, where they increase in 
height and sharpness as we pass backward in the direction of the thorax. Large, 
strong zygapophyses characterize the cervicals, and the transverse processes are 
thin, sharp and conspicuous. In the second to the sixth inclusive they are bent 
downward and project beyond the centra both in front and behind. These processes 
become suddenly contracted in the seventh cervical, where they more closely 
resemble those in the pre-dorsal series. Upon either side the vertebrarterial canal 
passes through all of the cervicals, save the seventh or last one. 
Metapophysial processes are first seen feebly pronounced on the third cervical, 
they grow stronger and stronger from before backward to include the sixth. On 
the seventh they are more or less aborted, as they are upon the first five dorsals, 
when they again make their appearance upon the sixth dorsal, as a feeble pair of 
minute spines pointing backward. After this they gradually increase in size to 
diminish again on the fourth lumbar, being entirely absent in the fifth, sixth and 
seventh lumbar, and the remaining part of the column. 
The ten first dorsal vertebrae are more or less like each other, while the last 
three dorsals, although they support true ribs, resemble the first lumbar. In the 
ten first dorsals the neural spines are very prominent, being well separated from 
each other in the articulated skeleton, lofty, laterally compressed, narrow, with 
nearly parallel anterior and posterior borders. This spine in the leading dorsal or 
thoracic vertebra has a height of two centimeters, and it is nearly perpendicular to 
the longitudinal axis of the centrum. In the tenth dorsal the neural spine is but 
one centimeter high, and the process leans backward. Between these two extremes 
a gradual change in form and height takes place from the first to the tenth inclu- 
sive. Thoracic vertebrae have their zygapophyses much reduced, but the inter- 
locking among them is very firm. Transverse apophyses are also inconspicuous in 406 
THE OSTEOLOGY OF VULPES MACROTIS. 
this part of the column. Laterally the heads of the ribs upon either side articulate 
between the facets of the centra, except in the last two pair, where they articulate 
entirely upon the body of the vertebra to which they belong. From the eighth 
thoracic to the ultimate lumbar inclusive the vertebrae increase in size and con- 
spicuousness. The neural spines, situated upon the fore part of the centra, lean 
forward, and are thin, narrow and laterally compressed. We find the tallest in 
the middle of this series, while the zygapophyses are strongly tilted upward in 
the last three dorsals and leading lumbar, to become slightly less and less so as the 
pelvis is approached. 
The transverse processes, bent downward, forward and outward, are narrow, 
thin, sharp plates, compressed from above downward, and in the last of the series 
have somewhat dilated .ends. They are hardly to be noticed in the last three 
thoracics, but after that they gradually commence to lengthen, until those on the 
last two lumbar vertebree attain a length of two centimeters each. The neural 
canal appears to have the least calibre in the post-thoracic region, and the greatest 
in the pre-cervical and post-lumbar. Throughout the chain at their ordinary sites 
in the carnivora, the usual foramina exist between the vertebral centra for the exit 
of the pairs of the spinal nerves. 
The three sacral vertebrce are all firmly anchylosed together, and present, both 
dorsally and ventrally, two pairs of neural foramina. Small neural spines are also 
present, but no hsemal ones. With respect to size, the first sacral is the biggest. 
It and the second offer strong lateral abutments for the ilia of the pelvis. It is 
only the fore part of the last sacral that does this,—the postero-lateral jDrocesses of 
this vertebra being free and directed backward and outward. Somewhat similar 
ones are developed upon the four leading caudal vertebrae, but the rest of the series 
of those in the tail become more and more rudimentary and elongated as we pass 
toward its tip, the last few again shortening, to become mere rodlets of bone, with 
barely any semblance whatever to a true vertebra. 
The Sternum.—Agreeing with other small vulpine forms among the Canidae, 
this part of the skeleton in Vulpes ynacrotis consists of eight pieces,—one being the 
presternum, one xiphisternum, and six pieces in the mesosternum. These latter 
decrease in size from before backward, being in any case but small subcylindrical 
rods of bone with enlarged extremities. They meet each other in subcircular disc- 
like articulatory facettes, the mesial extremities of the cartilagimous costal ribs 
articulating between them, one upon either side. The xiphisternum is represented 
merely by a long very slender piece of cartilage, while the presternum is longer 
than any of these sternal segments. 
Rather more anteriorly than midway on its shaft dorsad, there is a small pair 
of facettes, one upon either side, with which articulate the first pair of costal ribs. 
The apex of this piece of the sternum is bluntly rounded off. The second pair of 
costal ribs articulate at the junction of the presternum and first piece of the meso- 
sternum, while at the junction of the last piece and the xiphisternum two pairs of 
costal ribs articulate, and the extremities of a “floating pair” approach this point. THE OSTEOLOGY OF VULPES MACROTIS. 
407 
All of this arrangement agrees with what Professor Flower found in a domesticated 
dog, Cam's familiaris. The sternal or costal ribs appear to have a feeble,ossifica- 
tion of a somewhat granular nature. 
Their are thirteen pairs of true vertebral ribs, the first pair being the shortest 
and the ninth pair the longest. From the 8th to the 13th pair inclusive they are 
very slender, but slightly curved, and decidedly rod-like. The first pair of ribs are 
short, rather stout, and subcylindrical in form. They are likewise curved. In the 
first five pair, and especially in the first three pair, the sternal moities are dilated 
and flattened from side to side. All the leading pairs of these ribs have their 
vertebral ends completely developed, possessing all the characters known to be 
present in the ribs of the ordinary mammalia. As we pass posteriorly the features 
of the vertebral heads become gradually more rudimentary, especially in the matter 
of the disappearance of the neck, the tubercle and the angle, the capitulum alone 
remaining for articulation with the vertebra above. The last two or three pairs of 
the costal ribs do not meet the sternum, but come in contact with the same struc- 
tures in advance of them. Vulpes velox in all probability agrees with V. macrotis 
in all this part of its skeleton ; that is, in its vertebral column, sternum and ribs. 
The Shoulder Girdle. 
Many anatomatists have touched upon this part of the skeleton of the Canidm 
in osteological works. For example, Sir Richard Owen, in his second volume of the 
Comparative Anatomy and Physiolgy of Vertebrates, on page 510, said in effect 
that in the Canidse the scapulae, and especially the limb-bones, are longer and 
more slender relatively than in the Viverridae, Mustelidae and in the plantigrade 
carnivora. The clavicles are reduced to mere styles. Years afterward, Sir Wm. 
Henry Flower, in his Osteology of the Mammalia, stated that in “ the carnivora 
the anterior and posterior fossae of the scapula are nearly equal in area. [Refers to 
the scapula of the domestic dog as an example.] The spine and acromion are fairly 
developed, the latter often with a broad metacromial process. The coraicoid is 
much reduced.” According to Parker “a portion of the scapula, near the coracoid 
border, ossifies from an independent centre. The clavicle is sometimes absent, and 
when present varies much in its development, but is always rudimentary and sus- 
pended in the muscles, never reaching either the acromion or sternum. In the 
Felidae it is slender and curved, being longer than in any other members of the 
order. In the Canidse it is very short, and rather broad and flat. In most of the 
Ursidae it is absent.” 
The clavicles in the skeleton of V. macrotis before me are missing, but there 
is every reason to suppose that they agreed in their general characters with the 
vulpine carnivora generally; that is, in some respects they were rudimentary and 
did not reach either the acromion or the sternum; they have been lost in this par- 
ticular specimen. , 
The scapulce, however, are thoroughly developed and strong, well-ossified bones. 408 
THE OSTEOLOGY OF VULPES MACROTIS. 
The one from the left side is here shown in fig. 8 of Plate XXIII, seen upon its 
dorsal surface. A small double foramen, or twin foramina, are seen in the post- 
scapula part near the hinder margin, that may or not be present in the scapulm of 
other individuals. Sharp and thin, the decidedly convex margin of th& pro?scapula 
has its bounding rim slightly thickened, but not nearly so much so as the straight 
margin of the glenoid or posterior border, where, too, the edge for its entire length 
is raised and tilted outward and backward. On the other hand, the supra-scapular 
border, which is very slightly convex upward, has its edge about as thick as the 
antero-superior part of the coracoid or anterior border, and is the continuation of it. 
It meets the thickened glenoid border almost at a right angle, which angle is 
especially thickened. As to the amount of surface, the prcescapula and the post- 
scapula areas are about equal, while that of the mesoscapula presents an anterior 
surface about equal to half the praescapular area, and a posterior surface about equal 
to half the area of the postscapular. The inner or thoracic surface of the scapula 
is generally smooth, being but slightly ridged and roughened in certain places for 
the origin and insertion of muscles. There is a sub-vertical shallow groove present, 
extending from the glenoid cavity to the junction of the anterior and posterior 
borders that indicates the location of the base of the “ spine of the scapula.” or 
meso-scapula of the other side of the bone. An acromion process is well developed. 
If we hold the bone in its normal position as the animal stands up, it is gently 
curled backward. The coracoid is thick and strong, and it adds considerable 
strength to the anterior part of the glenoid cavity. This last has a subelliptical 
outline, is moderately concave, the major axis of the concavity being in the longitu- 
dinal direction, or in a plane roughly parallel to one in which the spinal column is 
situated. A slight constriction or neck joins the glenoidal portion of the scapula 
with its “ blade.” This scapula has an extreme height of about six centimeters 
and a width of about 3.5 cms. 
The Arm, Forearm and Manus (PI. XXIII).—In describing this part of 
the skeleton, as well as the bones of the posterior extremity, the terms of the 
relative position employed are those which the bones assume when the animal 
stands or walks in the ordinary way. 
Upon examining the humerus, it is found to present all the usual characters 
found in that bone among the Canidae generally. This statement also applies to 
the remaining bones of the pectoral limb, as well as to those of the skeleton of the 
hinder extremity. As shown in figure 9, the humerus is very slightly shorter than 
it actually is in life, judging from the specimen at hand. It has an extreme length 
of 9.2 cms., the ulna having a length of 10.2 cms., and the radius shorter than 
either measures but 8.7 cms. 
At the proximal extremity of the humerus we find the smooth, convex head of 
the bone, with its axis directed upward and backward. There is scarcely any neck 
between it and the rest of the bone, though the articular portion below curls over 
the part commonly so considered. To its inner side is the lesser tuberosity, it being 
well developed. To the outer side of this, and distinctly marked off by the rather THE OSTEOLOGY OF VULPES MACROTIS. 
409 
shallow bicipital groove, is the gi'eater tuberosity, it being broad, flattened from 
without inward, and having its thick, roughened, convex margin reared well above 
the general summit of the bone. Distally, at the other end of the humerus, the 
articular trochleo3 are conspicuously developed, being distinctly separated from each 
other by an intertrochlear groove, which is especially deep posteriorly. The radial 
condyle is small and pitted upon the outer aspect, while the ulnar or internal con- 
dyle is more prominent, has a very sharp and raised inner boundary, and develops 
a tuberosity instead of a pit upon its outer side. The deep anconeal fossa is per- 
forated by a large intercondylar foramen, and the supinator ridge, extending up the 
shaft from the external condyle is strongly marked. Another strong muscular 
ridge passes entirely down the shaft from the greater tuberosity to the internal 
condyle, it, at the lower end of the bone, being spirally parallel to the aforesaid 
supinator ridge. Between the two extremities, or the middle third of the shaft of 
the humerus, is otherwise smooth and subcylindrical in form; the shaft as a whole 
exhibiting a gentle sigmoid curve from one end to the other. Its deltoid ridge, 
occurring in the upper third of the shaft in the muscular line described above as 
passing down from the greater tuberosity, is but feebly pronounced, being not nearly 
as well marked as it is in some of the other carnivora, as for example in the Ursidae. 
In common with all other mammals the forearm or anti-brachimn has in its 
skeleton the two bones radius and ulna, both articulating with the humerus at 
their proximal extremities and with the upper row of the carpus, distally. Between 
the bones themselves the articulation is very close, both at their extremities and by 
elongated roughened facettes, one on either bone, at the junction of upper and 
middle thirds. Here a dense ligament helps to hold the bones together. As we 
have seen, the radius, although shorter than its companion, is much the stouter 
bone of the two, its antero-posteriorly flattened shaft is but very slightly bowed, 
and nearly of uniform calibre from one end to the other. Its extremities are en- 
larged for the articulatory purposes, as has already been stated. The facet for the 
humerus is of an oblong shape, and is co-extensive with the greater sigmoid cavity 
of the ulna. Distally, the carpal facet of the radius is much larger, also oblong in 
outline and concave. Here, anteriorly, on either hand occurs a deep, short groove, 
which in life transmits tendons. Flower says that the radius in the carnivora 
“ differs from that of man, inasmuch as its upper end is broad, flattened and extends 
further across the front of the humeral articular surface, forming part of the hinge; 
and although it is never ankylosed with the ulna, scarcely any appreciable amount 
of movement is allowed between them.” 7 
At the distal extremity of the antibrachium, the ulna is about equal in length 
to the radius, its end being considerably enlarged, projecting and mesially concaved 
in conformity with the radius in such a way as to complete the concavity in which 
the proximal row of carpal bones articulate.' This distal ulnar enlargement is less 
than one-third of that of the radius at the same extremity. Proximally, the ulna 
projects over a centimeter and a half beyond the radius, the projection being the 
' Loc. cit., p. 274. 
52 JOUKN. A. N. S. PHIL A., VOL. XI. 410 
THE OSTEOLOGY OF VULPES MACROTIS. 
olecranon or anconeal process,—the most conspicuous part of this bone of the fore- 
arm. It is strong, quadrilateral in outline, compressed from side to side. A deep, 
longitudinal notch is found on the supero-anterior angle of the olecranon. While 
its postero-internal aspect is somewhat concaved, caused by a prominent raised rim 
of the edges of the process, proximally and below. The sigmoid cavity is deeply 
sculpt, and its supero-anterior angle in some positions of the humerus will pass into 
the intercondylar foramen of that bone. 
For rather more than its superior third the shaft of the ulna is obliquely 
flattened, so that its anterior surface looks forward and outward. It gradually 
contracts as it approaches the above-described articulation with the radius in the 
narrow “interosseous space.” Below this point the shaft of the ulna is very slender 
and straight, and exhibits upon its inner aspect a fine, deep, longitudinal groove, 
which runs nearly to its distal end. Among all the carnivora we meet with this large 
compressed olecranon on the ulna, and observe that its shaft tapers gradually from 
above downward in the direction of the wrist. 
In the manus we have the carpus, metacarpus and phalanges. According to 
Flower, “ In the carnivora, the scaphoid and lunar bones always coalesce into a 
single scapho-lunar [as in Ursus america?ms~\, with which the ce7itrale is united, the 
latter never appearing8 as a distinct bone, except sometimes in very young animals. 
The radial accessory ossicle or sesamoid is generally present. All have five digits, 
with the complete complement of phalanges, except the Hyaena, in which genus 
the pollex is represented only by a rudimentary metacarpal. This digit is usually 
much reduced in size, and often, as in the dog, does not reach the ground in walking. 
It is best developed in the bears and allied forms. The first metacarpal is never 
more freely movable than any of the others. As a general rule the middle digit is 
somewhat the longest, the second and fourth nearly equal to it, the fifth shorter, 
and the first the shortest. 
“ As the toes are nearly always armed with long, strong, curved, and sharp 
claws, the ungual phalanges are large, strongly compressed, and pointed, and they 
develop from their base a broad, thin lamina of bone, which is reflected over the 
root of the horny claw, and holds it more firmly in place.” 9 
In Vulpes macrotis the radial accessory ossicle of the carpus is very small and 
rudimentary, while the pisiform on the ulnar side of the wrist is powerfully 
developed, and articulates with a distinct facet upon the outer side of the cunei- 
form. This latter bonelet, together with scapho-hmar, forms the convex proximal 
facet for articulation with the radius and ulna of the antibrachium, the last named 
affording about four-fifths of the surface, and articulating entirely with the radius. 
For the distal row we have four carpal bones, the largest of which is the unciform, 
which articulates with the proximal ends of the fourth and fifth metacarpals—the 
first, second and third metacarpals each having a small bone to itself. Of these 
8 B. G. Wilder, “ On the Composition of the Carpus in Dogg.” Bull. Cornell University, Vol. 
I, P. 301, 1874. 
9 Osteology of the Mammalia, pp. 287-289. THE OSTEOLOGY OF VULPES MACROTIS. 
411 
the outer one on the radial side is the trapezium, the next, the trapezoid, and the 
one next to the unciform, the os magnum. 
Agreeing in the main with the vulpine Canidse generally, the joints of the 
metacarpus present nothing of special note. As in the majority, if not in all true 
canines, the pollex metacarpal is much reduced in size, short and straight. Proxi- 
mally, its end is somewhat enlarged, but in its extreme length this bone is not over 
1.3 cms. in length. Its single phalanx and ungual joint are likewise greatly 
reduced, and it is more than probable that it plays but a feeble part in the 
locomotory functions of the fore-foot or paw, as it is doubtful that it reaches the 
ground in running, walking, or standing. The remaining four metacarpals are 
straight, stout and strong. At their distal ends each and all present the usual 
trochlear joints for the proximal articular extremities of the first row of pha- 
langes. Their upper ends are much compressed from side to side, and they fit so 
firmly against each other, that they are capable of scarcely any motion at all. 
Second, and fifth metacarpals are about of a length, each being about 2.8 centi- 
metres long, and the last named is the stouter bone of the two. Third metacarpal 
has a length of about 3.2 cms, and the fourth is very slightly shorter. These bones 
appear almost alike and both are slenderer than the fifth metacarpal. 
Free sesamoids do not appear to exist in any of tendons in the sole of the 
fore-foot of this little fox. Digits II-V each possesses two phalanges and a terminal 
ungual joint. The upper row of the former is composed of stout, short, straight 
bones, each presenting the usual articular ends as seen among the Canidae generally. 
The phalanges to the second and fifth digits are shorter and stouter than those to the 
third and fourth—the first averaging 1.3 cms in length, and the latter 1.7 cms. 
(II-V being nearly of a length, as are III and IV.) The distal row of phalanges 
is proportionately shorter and slenderer than the proximal row, but their general 
comparisons are about the same. Finally, the terminal row or ungual joints are 
each armed with a strong compressed osseous claw, which latter is curved and 
pointed. They have the thin basal lamina spoken of by Flower, but not as 
strongly developed as we find them in the Felidae. A minute tubular canal longi- 
tudinally pierces the core of each one of the bony claws of the fore-foot, apparently 
for the passage of the vessels to its apex, where it opens, for the horny sheath 
covering it during life. As in other small Canidae, the middle digit is rather 
longer than any of the others, the second and fourth being somewhat shorter than 
it, fifth still shorter, and pollex, as already stated, shorter than any of them by far. 
Indeed, the entire length of this digit is not sufficient to carry the apex of its 
ungual joint past the distal end of the second metacarpal bone alongside of it. 
The Pelvic Girdle and the Skeleton of the Hinder Limb. 
Sir Richard Owen, in liis Comparative Anatomy and Physiology of the Verte- 
brata does not give us a dozen lines upon the pelvis in the carnivora; and Flower 
in the last edition of the Osteology of the Mammalia hardly does more, and neither 
of these distinguished authorities refer to the pelvis of the genus Vulpes. On speak- 412 
THE OSTEOLOGY OF VULPES MACROTIS. 
ing of the carnivora as a group, Flower says in the work just cited, that “the pelvis 
is generally elongated and narrow, the ilium and ischium being in a straight line, 
and of nearly equal length. In most species the ilia are straight, flattened, and not 
everted above [makes reference to his figure of the pelvis of a dog, Fig. 115, p. 
317], the iliac surface is very narrow and confined to the lower part of the bone, 
as the acetabular and pubic borders meet in front above; the gluteal surface looks 
directly outwards and is concave; the sacral surface forms a broad flat plane above 
the attachment to the sacrum, the crest being formed by the united edges of the 
sacral and gluteal surfaces, instead of the iliac and gluteal surfaces, as in man. 
The symphysis is long; it includes part of both pubis and ischium, and commonly 
becomes completely osseous in adult animals. The thyroid foramen is oval, with 
its long axis parallel to that of the whole bone. The ischia are wide and divergent 
posteriorly. 
“ In the Hymna the pelvis is shorter and wider than in most other carnivora, 
both the upper ends of the ilia and lower ends of the ischia being considerably 
everted.” 
Now in Vulpes macrotis the pelvis is by no means unlike that part of the 
skeleton as we find it in some of the more fox-like species of the domesticated dogs. 
Flower figures the “ventral surface of right innominate bone of dog (I)” in his 
Osteology of the Mammalia and in its general features it very closely resembles 
the same surface of the pelvis of the fox now being considered, and the description 
above quoted likewise answers very well in describing the same. There are plenty 
of half-breed Indian dogs in the Indian camps of the northwestern parts of the 
United States that doubtless possess pelves with characters almost identical with 
those of Vulpes. 
The ilia of this pelvis have the sacrum of the vertebral column wedged in 
between them quite as firmly as we find it in man and many other animals, and 
the articular surface for the articulation with the sacrum is of the same roughened 
character. Above this surface the blade of an ilium rises for more than a centi- 
metre, its superior crest being convex, while its external surface is markedly con- 
caved. The posterior borders of the ilia are very nearly in the same plane with 
the ischia, and in fact the pelvis as a whole is much compressed in the antero- 
posterior direction. Scarcely any indication of a “greater sacro-sciatic notch” or a 
“ lesser sacro-sciatic notch” is present, though on the anterior rim of the basin of 
this pelvis, a rudimentary anterior superior spine is seen, the anterior inferor spine 
being well-marked and conspicuously developed. Either acetabulum is a hemis- 
pherical concavity with an average width of nine millimetres. Its base is not 
perforated by a foramen, while the cotyloid notch at its lower part is distinctly 
marked. The symphysis pubis is very firmly co-ossified for its entire length, the 
suture being almost obliterated upon its dorsal aspect. It has a length of 2.3 cms. 
and the pubic arch is wide and much concaved. Each obturator foramen is very 
large and of a subcircular outline, with an average diameter of eleven millimetres. 
In the middle line at the narrowest place their peripheries are but 3.5 millimetres THE OSTEOLOGY OF VULPES MACROTIS. 
413 
apart. Below, and to the outer side of one of these foramina, the surface of the 
ischium is broad, flat and quite extensive, with its outer angle thickened and 
prominent. This last is the “ tuberosity of the ischium,” and it is far more con- 
spicuous than it is in Homo and the apes. Laterally, an ischium is concaved on 
its border, while interiorly it is convexed and rimmed. The inlet of this pelvis has 
a median longitudinal diameter of 2.5 centimetres, and a transverse diameter of 
2.3 cms. at its widest part—in other words the inlet is nearly circular in outline. 
Passing to the skeleton of the thigh, leg and pes, we find the femur of the first- 
named division of this limb to be a very interesting bone, with well-pronounced 
characters. Viewing it upon its anterior aspect its more or less slender subcylin- 
drical shaft appears to be nearly straight from one extremity to the other, but seen 
on lateral view, there is a gentle curvature backward to be recognized, especially at 
the distal half, and this is here enhanced by the remarkable manner in which the 
large condylar end is produced posteriorly. This part is massive and profoundly 
channeled by the intercondyloid notch behind, to a lesser degree below, and rather 
faintly in front. The condyles are nearly equal in size, the external one being 
rather the larger, while both are situated on the same level distally. Their 
external surfaces are more or less smooth, the tuberosities above the external 
condyle alone being in evidence to break the general smoothness of the surface of 
this distal end of the femur. 
Proximally, the bone presents for examination the head, neck and the greater 
and lesser trochanters. Head and neck are almost exact miniatures of those we 
find on the femur in a man, the former being quite hemispherical in form, and the 
latter constricted and proportionately a little shorter. A distinct depression for the 
ligamentum teres is present, and the axis of the neck makes an obtuse angle of some 
135° with the longitudial axis of the shaft. Rising no higher above the summit of 
the bone than the head, the trochanter major is strongly developed, and has a deep 
excavation on its postero-internal aspect. Standing between this and the neck, and 
two or three millimetres below both, we meet with the trochanter minor, here very 
distinctly developed as a small but conspicuous tuberosity. Passing just to the 
inner side of this, and running down the shaft obliquely to the junction of upper 
and middle thirds, and from thence straight down to the smooth and flat “popliteal 
space,” is a “muscular line” or ridge, best marked in the upper third of its course. 
A similar line (linea aspera) passes from the base of the trochanter major, its outer 
aspect, to run down in nearly a straight line to the tuberosity above the external 
condyle, where it stops. These two muscular lines are parallel and quite close 
together for the whole middle third of the femoral shaft. Nutrient foramina occur 
on the anterior aspect of the trochanter major, in the intercondyloid notch, and on 
the side of the internal condyle, a fact that inclines me to think that there is no 
regular site for these openings. 
Fabellce are also present at the back of the knee-joint of this fox, a small 
ossicle or fabella being found in the ligament posterior to either condyle; but the 
sesamoid spoken of by Flower as “ a wedge-shaped bone within the joint, lying on 414 
THE OSTEOLOGY OF VULPES MACROTIS. 
the articular surface of the tibia, an ossification of the internal inter-articular semi- 
lunar cartilage,” does not appear to be present, A patella of some size, however 
(8 mm. long), and of an oval form, exists in its usual place in the common extensor 
tendon at the front of the knee-joint. Its anterior surface is convex and roughened, 
while posteriorly it presents an articular facet for each femoral condyle. 
Morphologically, the tibia and fibula of the leg are interesting bones. Viewing 
the former upon its anterior aspect it will be noticed that the upper moiety of the 
shaft is gently curved in such a manner that it is concave on its outer side and 
correspondingly convex upon its inner side. Below the middle of the bone it is 
nearly straight, with a slight inclination, however, to exhibit a curvature the 
reverse of what has just been described as being found in the upper half. Again 
the upper half of the tibia is massive and strong, the crest upon its anterior aspect 
being prominently developed. This feature is most conspicuous above, gradually 
disappearing as the middle of the shaft is approached, after which this part of the 
bone is compressed in the antero-posterior direction. A horizontal section made 
first below the summit would be distinctly triangular, and a similar one made in 
the lower third would be elliptical. Seen from above the summit of the tibia has a 
cordate outline, the apex being to the front, and the figure completed by a median 
notch behind. In this latter locality the margins are curled downward, and par- 
ticularly so where the fibular articulation is found, so that this facet is beneath this 
projecting part of the summit of the tibia, and consequently the fibula is shorter 
than the former bone proximally. 
The tibial shaft is wonderfully smooth, and exhibits longitudinal muscular 
ridges only at its upper third at the posterior aspect. Distally, its extremity is but 
moderately enlarged, and compressed from before backward. Its basal aspect is 
peculiarly concaved in order to articulate with the astralagus of the tarsus. This 
concavity would not be suspected simply by viewing the bone directly from in front, 
from behind, or from the side, so completely is it on the basal end of the shaft. 
It is marked by a distinct and deep little notch anteriorly, close to the internal 
malleolus. 
The fibula is an exceedingly slender bone of uniform calibre, being markedly 
compressed from side to side, including its extremities, which are rounded and 
dilated. The upper one of these articulates with the tibia in the manner described 
above, while the lower one projects beyond the end of the former, where it becomes 
the external malleolus of the ankle-joint. Owing to the aforesaid curvature of the 
upper half of the tibial shaft, the fibula stands far apart from its companion in that 
part of the skeleton of the leg, but below the middle of the shaft, these two bones 
come in contact, and from this point to the distal fibular enlargement (external 
malleolus) they are in extremely close contact, probably actually co-ossified in very 
old individuals. Flower says the “ fibula is slender, and in dogs curved towards 
the tibia, the lower half being closely applied to that bone.” This is true only 
in part, as proximally it is the tibia that is curved away from the fibula, the 
latter, as has been said, being almost perfectly straight from one end to the other. THE OSTEOLOGY OF VULPES MACROTIS. 
415 
Vulpes macrotis, in common with other terrestrial carnivores, has the skeleton 
of pes divided into three parts, namely, the tarsus, the metatarsus, and the digits 
or phalanges. The tarsus is composed of seven distinct bones articulating with 
each other in a manner similar to what is known to occur in the tarsi of other 
representatives of this group. These bones are the astralagus, the os calcis or 
calcaneum, the scaphoid or navicular bone, the three cuneiform bones (internal, 
middle and external), and the cuboid. 
Morphologically, the astralagus is composed of the tibiale and the intermedium, 
the internal cuneiform is the first tarsal (tarsale I), the middle the second, the 
external the third, and the cuboid the united fourth and fifth tarsals (tarsale IV 
and V). 
The metatarsus of V. macrotis consists of four much elongated metatarsal 
bones, of a very rudimentary, hook-like hallux, only 4.5 mm. long, and freely 
articulating with the anterior facet upon the internal cuneiform. On the under 
side of each distal trochlear extremity of the fully developed metatarsal bones we 
find a pair of large sesamoids. Each pair of these sesamoids is so disposed as to give 
the appearance of being but a single one, deeply grooved in the longitudinal direc- 
tion, both on the dorsal as well as the ventral aspects. They are in the plantar 
tendons of pes. The podal phalanges closely resemble those of the manus, and 
have bones of the same number, and nearly of the same form and size. Great 
beauty of adaptation and movement characterizes the ankle-joint of this fox, 
especially in its articulation with the bones of the leg. 
The astragalus is a very irregularly formed bone, consisting of a trochlear 
portion and head. The latter is a cuboidal projection that extends forward from 
the antero-internal aspect of the former, and has its distal, vertical face entirely 
occupied by a slightly convex, smooth facet for articulation with the navicular bone 
or scaphoid. Seen from above, the trochlear part of the astragalus has a most 
perfect articulation of that character, reminding one at onoe of the distal end of a 
phalanx in the manus of Homo, or in the pes of any large true raptorial bird. 
Its median groove is longitudinal, and extends from the head of the bone backward 
clear around and under for some distance, making in all a beautiful curved surface. 
The lateral margins are somewhat sharp, especially the inner one, which in the 
articulated ankle fits into the little narrow and deep notch which was described 
above as being found on the anterior distal margin of the basal part of the tibia. 
This admirable arrangement prevents to a great degree the danger of the lateral 
dislocation of the bones ot the leg and the tarsus from any violence or sudden 
sprain in running. 
On the under side of the astragalus there is a somewhat irregular trochlea for 
articulation with the os calcis. Its convexity is transverse or just the reverse of 
the one on the upper side of the bone. Furthermore we find here a minute longi- 
tudinal groove passing toward the head of the bone, but with its posterior extemity 
terminating in a deep pitlet. Internally, the surface of the astragalus is extensive 
and undulating; externally, it is narrow and markedly curved, the curve corre- 416 
THE OSTEOLOGY OF YULPES MACROTIS. 
sponding to the curve of the internal trochlea of the superior aspect. When 
normally luxated, the astragalus rests upon the supero-internal aspect of the os 
calcis and articulates with it by two facets. Above, it articulates with the tibia 
and fibula; the former monopolizing all of the trochlear surface, while the infero- 
internal aspect of the distal end of the latter articulates with the greatly curved 
and narrow facet, described above as composing the outer surface of the tarsal bone 
under consideration. 
The os calcis or calcaneum has an extreme length longitudinally of 2.4 cms., 
and a width of one centimetre, measured at its widest part across the articulation 
for the astragalus. This latter occupies the anterior half of the bone superiorly, 
while its anterior face is occupied by a vertical facet devoted to the articulation 
with the cuboid. The posterior half of the calcaneum is rather deep, com- 
pressed from side to side, with the free upper extremity enlarged, and bears a 
smooth, vertically convexed, laterally concaved surface for the insertion of the 
distal end of the tendo Achillis. The “ lesser process” of the os calcis is well 
developed, and beneath it is plainly to be seen the groove for the passage of the 
tendon of the flexor longus pollicis muscle. Flower says10 that the recent researches 
of Baur, On the Morphology of the Tarsus in the Mammals, “American Naturalist,” 
January, 1885, make it probable that a certain bone on the tibial side of the tarsus 
of Hyrax, many Edentates, Ornithorhynchus and rodents,—and hitherto looked 
upon as a sesamoid bone,—is the rudimentary tarsale tibiale, whilst the astragalus 
is the intermedium representing the lunare of the hand. This tibiale is frequently 
fused with the centrale, the navicular bone in such cases containing the elements 
of the centrale and tibiale.” Again, in the same work, on page 342, he says, “ In 
addition to these constant tarsal bones, there may be supplemental or sesamoid 
bones; one situated near the middle of the tibial side of the tarsus, largely 
developed in many carnivora and rodents; another, less frequent, on the flbular 
side; and a third often developed in the tendons of the plantar surface of the 
tarsus, especially large in the armadillos. There is also usually a pair of sesa- 
moid bones opposite each metatarso-phalangeal articulation on its plantar aspect.” 
In carefully examining these parts in Vulpes macrotis it becomes clear that the 
first-mentioned bone (or sesamoid ?), considered in the above footnote to be the 
tibiale, is fused with the ce?itrale or navicular bone on its plantar side. The smaller 
one, on the flbular side, if present at all, must be either extremely rudimentary or 
else co-ossified with some other tarsal element. It was not found in this fox. In a 
former paragraph, the paired sesamoids on the plantar aspect of each metatarso- 
phalangeal articulation, have already been described. 
Passing to the cuboid we meet with a large strong bone having a length equal 
to that of the scaphoid and external cuneiform combined. It articulates with both 
of these bones as well as with the proximal extremities of the fourth and fifth 
metatarsals anteriorly and the os calcis behind. Dorsallv, the bone is comparatively 
smooth, while on its ventral side in front it presents a deep groove, which crossing 
10 Osteology of the Mammalia, Third edition, p. 340. THE OSTEOLOGY OF VULPES MACROTIS. • 
417 
this surface obliquely, is intended to lodge the tendon of the peroneus longns 
muscle. On the external aspect the commencement of this groove is indicated by 
a deep notch, which in life is converted into a foramen by the ligament stretching 
across it from the fifth metatarsal to the cuboid itself. 
The scaphoid is a short, subcylindrical segment of some size, with a round 
concave facette for the astragalus, and, anteriorly, facettes for the three cuneiform 
bones, and it articulates with all of these elements. Below, it fuses with a large 
plantar sesamoid. 
Having a very regular appearance, the three cuneiform bones are wedged in 
between the scaphoid behind, and the rudimentary hallux, and the second and 
third metatarsals in front. In point of size, the external cuneiform is the largest, 
the internal the next biggest, and the middle one the smallest of the three. The 
internal one develops a conspicuous plantar process for the attachment of ligaments. 
Anteriorly, it articulates with hallux and second metatarsal. The middle or shortest 
cuneiform, articulates anteriorly, only with the second metatarsal, while the longer 
external cuneiform articulates with the proximal end of the third metatarsal. 
Apart from the rudimentary hallux, all of the four remaining metatarsals are 
long, rather stout, and subcylindrical bones. Proximally, they are crowded close 
together, practically firmly moulded upon each other for at least one-third of this 
part of their lengths, and this in such a manner that from side to side they otfer 
dorsally a marked convex surface as compared with the far shallower concave sur- 
face on their plantar aspects when similarly considered. As they extend forward 
toward the toes, the two middle ones very slightly part company, and so their 
shafts keep nearly straight, but the second and fifth each somewhat curve away 
from the longitudinal median plane, and thus their shafts exhibit this curvature. 
The second metatarsal is the stoutest of the four, and the third the slenderest. 
Third and fourth each have a length of 4.6 centimeters, while second and fifth 
measure but 4.2 cms. Distally, they present the usual trochlear heads for the 
articulations of the posterior extremities of the corresponding podal digits. These 
last each possess two phalangeal joints, and terminate with a freely articulated 
osseous ungual claw, all morphologically similar to what we find in the digits of 
man us. 
The character of the articulation between the metatarsal joint and the phalanx 
in the case of any toe is different from what is found between the two joints of the 
toe itself. In the first instance the head of the metatarsal bone has a convex, 
subellipsoidal articulation dorsad, and a sharp, median longitudinal keel on the 
plantar aspect. The rounded surface articulates with a corresponding facet on the 
proximal end of the phalanx, but below this, the articulation is deeply notched in 
the median line in order to admit the aforesaid keel on the end of the metatarsal, 
and this is kept in place in life by the paired sesamoids and the plantar tendons. 
The interarticulation between the phalangeal joints themselves is of the simpler 
trochlear type, such as we find in the case of the joints in the manus or pes of 
Homo, and between the last phalanx in any toe and its ungual joint the plan is 
53 JOURX. A. N. S. PHILA., VOL. XI. 418 
THE OSTEOLOGY OF VULPES MACROTIS. 
even still simpler, the trochlear head being less evidently defined. Vulpes macrotis 
has the skeleton of its second toe equal in length to that of the fifth, and that of 
the third equal to that of the fourth,—the bones all being strong, stoutish and well- 
proportioned. The second toe has a length of about 3.4 centimeters, and the third 
4.0 centimeters. These measurements include the ungual joints, and all the bones 
normally articulated. In the case of any digit, its proximal joint is about one- 
fourth longer than the next one beyond. For example, the length of the proximal 
joint of the fourth digit is 1.8 cms., the next joint in the same toe being 1.4 cms., 
and their calibres vary in proportion. The sharp-pointed angular joints exhibit but 
little curvature, and at their articulations their basal portions extend plantar-wards 
as a process, in each case, for the insertion of the plantar tendon of the flexor 
longus digitorum. 
EXPLANATION OF PLATES. 
All the figures are of natural size, except fig. 12 of Plate XXIII, and from 
photographs made direct from the specimens by the author. 
Plate XXII. 
Fig. 1. Left lateral view of the skull and lower jaw of Vulpes macrotis. 
Fig. 2. Dorsal aspect of the skull of Vulpes velox, the mandibles having been 
removed. 
Fig. 3. Lower jaw or mandible of Vulpes macrotis, viewed from above. 
Fig. 4. Right ramus of mandible of Vulpes velox, seen from above, and 
rotated inward. Tip of canine tooth, and the incisors broken off; molars and 
other teeth complete and in position. 
Fig. 5. Ventral aspect of the skull of Vulpes velox (same specimen as is shown 
in fig. 2). The lower jaw has been removed. 
Fig. 6. Ventral aspect of the skull of Vulpes macrotis. 
Fig. 7. Dorsal aspect of the skull of Vulpes macrotis. Same specimen as is 
shown in fig. 6. 
Plate XXIII. 
Fig. 8. Left scapula of Vulpes macrotis, external surface. 
Fig. 9. Dorsal surface of the left humerus of Vulpes macrotis, showing the 
preaxial border, greater tuberosity, and the external condyle. 
Fig. 10. Anterior view of the left femur of Vulpes macrotis. 
Fig. 11. Left tibia and fibula of Vulpes macrotis, normally articulated, and 
viewed upon external aspect. (All the bones, except those shown in figs. 2, 4, and 
5, of PI. XXII, belong to the one and same individual in author’s collection, the 
ramus of the jaw in fig. 4, PI. XXII, belonging to the specimen of V. velox of the 
U. S. Nat. Museum, No. 15,355.) 
Fig. 12. Right lateral aspect of the skeleton of the trunk of Vulpes ?7iacrotis. 
(Reduced rather less than one-half.) Naturally articulated, and the dried ligaments 
and cartilaginous costal ribs not removed. Exhibits the normal relations of the 
bones of the trunk. JOURN. ACAD. NAT. SCI. PHILA., 2ND SER., VOL. XI. 
PLATE XXII. 
SHUFELDT. OSTEOLOGY OF VULPES MACROTUS. ' / ■ ■ / 
J0URR. ACAD/ NAT. SCI. PHILA.. 2ND SER„ VOL. XI. 
PLATE XXIII. 
SHUFELDT. OSTEOLOGY OF VULPES MACROTUS.