Dr. Wyman on the Blind Fishes of the Mammoth Cave. 259 
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 
herve (fig. la) was distinetly 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 ‘vf 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 
hot 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 under the microscope with a power of about twenty 
diameters, the following parts were satisfactorily made out: Ist, 
®Xternally an exceedingly thin membrane, 6, 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 tegarded as a sclerotic ; 2d, a layer of pigment cells, d, for 
& Most part of a hexagonal form, and which were most abund- 
“nt about the anterior part of the eye; 3d, beneath the pigment 
4 Single layer of colorless cells, c, larger than a pigment cell, and 
fach cell having a distinct nucleus; 4th, just in front of the 
aiahe, a lenticular shaped, transparent body, e, which consisted of 
€xternal membrane coutaining numerous cells with nuclei. 
his lens-shaped body seemed to be retained in its place bya 
sth ugation forwards of the external membrane of the globe; 
“, the globe was invested by loose areolar tissue, which ad- 
fate to it very generally, and in. some instances contained yellow 
ty Matter; in one specimen it formed a round spot visible 
