[From the American Journal of Science and Arts, March, 1854.] , 
On the Eye and the Organ of Hearing in the Blind Fishes 
(Amblyopsis spelccus, Dekay) of the Mammoth Cave. 
By Jeffries Wyman, M.D. 
The general structure of the blind fishes was described in a 
former number of this Journal,* but a more complete descrip- 
tion was given in the New York Journal of Medicine, by Tel- 
kampf, who in company with J. Muller of Berlin, for the first 
time detected the existence of rudimentary eyes.f They are de- 
scribed as one twelfih of a line in diameter, round, black, desti- 
tute of a cornea, having an external layer of pigment, beneath 
which is a colorless membrane. No nerve was detected in con- 
nection with the eye, and the contents of the globe were not 
determined with certainty. Prof. Owen has described the organ 
as a simple eye-speck, “as in the leech, consisting of a minute 
tegumentary follicle, coated by dark pigment which receives the 
end of a special cerebral nerve.”| Dr. John C. Dalton, Jr. has 
also detected the eyes and describes them as minute globular sacs 
containing blackish pigment, deeply imbedded in the adipose tis- 
sue of the orbit and measuring a little less than one seventy- 
eighth of an inch.<§> 
Through the kindness of Mr. Charles Dean of Cambridge, 
and of Prof. Agassiz, I have had placed at my disposal some speci- 
mens of Amblyopsis, well preserved in alcohol, and have been 
able to make in some respects a more complete description than 
has as yet been given. I have had also an opportunity of inspect- 
ing superficially fourteen specimens varying from one inch and a 
half to four inches and a half in length, but in three or four only 
* Vol. xlv, p. 94, July, 1843. 
f New York Journal of Medicine, vol. v, p. 84, 1845. Dr. Dekay had previously 
mentioned the existence of eyes, but was evidently misled by some other appear- 
ance, since he states that eyes exist of the usual size, but are covered by the skim 
He had not dissected them. Fauna of New York. 
$ Lectures on Comp, rtnat., vol. ii, p. 202. See also his figure, p. 175. 
§ New York Medical Times, voL ii, p. 854. Dr. Wyman on the Blind Fishes of the Mammoth Cave. 
2 
could the eyes be detected through the skin. In the three speci- 
mens recently dissected, the eyes were exposed only after the 
removal of the skin, and the careful separation from them of the 
loose areolar tissue which fills the orbit. In a fish four inches 
in length the eyes measured one-sixteenth of an inch in their 
long diameter, were of an oval form and black. A filament of 
nerve (fig. la) was distinctly traced from the globe to the cranial 
walls, but the condition of the contents of the cranium from the 
effects of the alcohol, was such as to render it impracticable to 
ascertain the mode of connection of the optic nerve with the 
optic lobes. A few muscular fibres were traced to the immediate 
neighborhood of the eye, and even in contact with it, but were 
not ascertained to have that regular arrangement which is seen in 
the more completely formed eyes of other fishes. 
Eye of Amblyopsis. 
Brain and auditory apparatus. 
Examined underthe microscope with a power of about twenty 
diameters, the following parts were satisfactorily made out: 1st, 
externally an exceedingly thin membrane, b, which invested the 
whole surface of the eye and appeared to be continuous with a 
thin membrane covering the optic nerve, and which was there- 
fore regarded as a sclerotic ; 2d, a layer of pigment cells, d, for 
the most part of a hexagonal form, and which were most abund- 
ant about the anterior part of the eye ; 3d, beneath the pigment 
a single layer of colorless cells, c, larger than a pigment cell, and 
each cell having a distinct nucleus; 4th, just in front of the 
globe, a lenticular shaped, transparent body, e, which consisted of 
an external membrane containing numerous cells with nuclei. 
This lens-shaped body seemed to be retained in its place by a 
prolongation forwards of the external membrane of the globe ; 
5th, the globe was invested by loose areolar tissue, which ad- 
hered to it v/sry generally, and in some instances contained yellow 
fatty matter; in one specimen it formed a round spot visible 3 
Dr. Wyman on the Blind Fishes of the Mammoth Cave. 
through the skin on each side of the head, which had all the ap- 
pearance of a small eye;—its true nature was determined by the 
microscope only. It is not improbable that the appearance just 
referred to may have misled Dr. Dekay—where he states that 
the eye exists of the usual size, but covered by the skin. 
If the superficial membrane above noticed is denominated cor- 
rectly the sclerotic, then the pigment layer may be regarded as 
the representation of the choroid. The form as well as the posi- 
tion of the transparent nucleated cells within the choroid corres- 
pond for the most part with the retina. All of the parts just 
enumerated are such as are ordinarily developed from and in con- 
nection with the encephalon, and are not in any way dependent 
upon the skin. But if the lenticular shaped body is the true rep- 
resentative of the crystalline lens, it becomes difficult to account 
for its presence in Amblyopsis according to the generally recog- 
nized mode of its development (since it is usually formed from an 
involution of the skin) unless we suppose that after the folding 
in.of the skin had taken place in the embryonic condition, the 
lens retreated from the surface, and all connection with the integ- 
ument ceased. . 
According to Quatrefages, however, the eye of Amphioxus is 
contained wholly in the cavity of the dura mater, and yet it has 
all the appearance of being provided with a lens. If his descrip- 
tion be correct, then the mode of development as well as the 
morphology of the eye in this remarkable fish is different from 
that of most other vertebrates, since the lens never could have 
been formed from an involution of the skin, nor could the eye 
with its lens, as Prof. Owen asserts, be a modified cutaneous fol- 
licle. That there should be different modes of development of 
parts of the eye in different animals is by no means improbable, 
since we find this actually to be the case in'another organ of 
sense, the nose. In some fishes the nostrils result from a depres- 
sion or involution of the skin simply, and do not at any period 
communicate with the mouth ; while in all of the higher verte- 
brates they are formed by subdivision of the primitive oral cavi- 
ty. It is possible, therefore, that in Amblyopsis the lens may 
have been developed where we find it, and that it was never con- 
nected with the integument. Whatever views be taken with 
regard to its development, the anatomical characters which have 
been enumerated show, that though quite imperfect as we see it 
in the adult, it is constructed after the type of the eyes of other 
vertebrates. It certainly is not adapted to the formation of ima- 
ges, since the common integument and the areolar tissue which 
are interposed between it and the surface would prevent the trans- 
mission of light to it except in a diffused condition. No pupil 
or anything analogous to an iris was detected, unless we regard 
as representing the latter the increased number of pigment cells 
at the anterior part of the globe. Dr. Wyman on the Blind Fishes of the Mammoth Cave. 
4 
The Ear.—It is said that the blind fishes are acutely sensitive 
to sounds as well as to undulations produced by other causes in 
the water. In the only instance in which I have dissected the 
organ of hearing (which I believe has not been before noticed) 
all its parts were largely developed, as will be seen by reference 
to figures 2 and 3. As regards the general structure, the parts do 
not differ materially from those of other fishes except for their 
proportional dimensions. The semi-circular canals are of great 
length, and the two which unite to enter the vestibule by a com- 
mon duct, it will be seen, project upwards and inwards under the 
vault of the cranium, so as to approach quite near to the corres- 
ponding parts of the opposite side. The otolite con- 
tained in the utricle was not remarkable, but that of 
the vestibule (fig. 3) andwhich is seen in dotted out- 
line in fig. 2 e is quite large when compared with that 
of a Leuciscus of about the same dimensions as the 
blind-fish here described. 
The parts represented in fig. 2 are the olfactory lobes and 
nerves a, the cerebral lobes h, optic lobes c, the cerebellum d, the 
otolite in situ e, the medulla oblongata f and the eyes g. 
The parts in figures 2 and 3 are enlarged three times linear 
measurement. 
Ololile.