8 THE BLIND FISHES OF MAMMOTH CAVE. 
pout or horned pout, and of about the same size (ten inches in 
length). It was taken in the Conestoga river in Lancaster Co., 
Penn., where it is “occasionally caught by fishermen and is sup- 
posed to issue from a subterranean stream said to traverse the 
limestone in that part of Lancaster Co., and discharge into the 
Conestoga.” We quote the sMo from Prof. Cope’s remarks 
on the fish : * — 
“ Two specimens of this fish present an ae wa condition of 
the rudimental eyes. On the left side of both mall perforation 
exists in the corium, which} is closed by the epidermis, representing 
a rudimental cornea; on the other the corium is complete. Here 
the eyeball exists as a very small cartilaginous sphere with thick 
walls, concealed by the muscles and fibrous tissue attached, and 
by a minute nucleus of pigment. the other the sphere is 
larger and thinner walled, the thinnest portion adherent to the 
corneal spot above mentioned ; there is a lining of pigment. It 
is scarcely Bee thee in one, in the other so closely as to give a 
tripodal section. Here we have an interesting transitional condi- 
nee in one and the same animal, with regard to a peculiarity which 
has at the same time phy siological and systematic significance, 
sit Si is one of the comparativ ely. few cases Afees the phy ysiological 
appr opriateness of a generic modification can be demonstrated. It 
is therefore not subject to the diffculty under which the advocates 
of natural selection we when necessitated to explain a structure 
as being a step in the advance towards, or in the recession from, 
any unknown saiit ioh needful to the existence of the species. 
In the present case observation on the species in a state of nature 
may furnish interesting results. In no specimen has a trace of 
anything representing the lens been found.” 
When we remember that the lens of the eye in Amblyopsis has 
been found, even though the eye is less developed in all its parts 
than in Gronias, it is probable that a careful microscopical exami- 
nation would show its existence in this genus also. 
It is interesting to note that this fish is black above (lighter on 
the sides and white below), notwithstanding its supposed subter- 
ranean habits, and that all the other members of the family having 
rudimentary or covered eyes are also dark colored, while the blind 
fishes of the Mammoth Cave and of the caves in Cuba are nearly 
colorless. This want of color in the latter fishes has been consid- 
ered as due to their subterranean life. If this be the cause, why 
should the blind cat fishes retain the colors characteristic of the 
other members of the family living in open waters? 
* Proceedings of the Academy of Natural Sciences of Philadelphia for 1864, p. 231. 
Se Sapna 
