THE EYES OF THE BLIND FISHES. 
41 
The lateral branch was not traced distinctly to an end, but seemed 
to connect with the olfactory cavity. The walls of these canals 
are exceedingly delicate and easily overlooked.” — Wyman. 
“Plate 1, fig. 5, shows the globe of the eye with the optic nerve 
(c), as seen under the microscope. The lens {b) is detached from 
its proper place by the pressure of the glass. Irregularty arranged 
muscular bands are attached to the exterior of the globe (a, a, a, 
a), but were not recognized as the homologues of the muscles of 
the normal eye of fishes ; nevertheless, they indicate that the globe 
was movable.” — Wyman. 
“In the three specimens recently dissected, the eyes were ex- 
posed 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, and were of an oval form and black. A 
filament of nerve (PI. 1, fig. Sa) 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. 
Examined under the microscope with a power of about twenty 
diameters, the following parts were satisfactorily made out (PI. 1 , 
fig. 3) : 1st, externally an exceedingly thin membrane, 6, which 
invested the whole surface of the eye and appeared to be continu- 
ous with a thin membrane covering the optic nerve, and was 
therefore regarded as a sclerotic ; 2d, a layer of pigment cells, d, 
for the most part of a hexagonal form, and which were most abun- 
dant about the anterior part of the eye ; 3d, beneath the pigment 
a single la 3 "er 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 [see also fig. 4], 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 adhered 
to it very general!}' , and in some instances contained yellow fatty 
matter ; in one specimen it formed a round spot, visible through the 
skin on each side of the head, which had all the appearance of a 
small eye ; its true nature w^as 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 position 
of the transparent nucleated cells within the choroid correspond 
