THE BLIND FISHES OF MAMMOTH CAVE. 25 
as well developed as those of Chologaster cornutus, an argument 
in favor of the theory that the fishes were always blind and that 
they have not become so from the circumstances under which they 
exist? If the latter were the case and the fishes have become blind 
from the want of use of the eyes, why are not the optic lobes also 
atrophied, as is known to be the case when other animals lose their 
sight? I know that many will answer at once that Amblyopsis 
and Typhlichthys have gone on further in the development and 
retardation of the characters best adapting them to their subterra- 
nean life, and that Chologaster is a very interesting transitionary 
form between the open water Cyprinodontes and the subterranean 
blind fishes. But is not this assumption answered by the fact that 
Chologaster has every character necessary to place it in the same 
family with Amblyopsis and Typhlichthys, while it is as distinctly 
and widely removed from the Cyprinodontes as are the two blind 
genera mentioned ? 
Assuming, for the momeat, that Chologaster is ‘a transitional 
form between the surface feeding Cyprinodontes, and Typhlichthys 
and Amblyopsis, let us recapitulate the characters that distinguish 
the different forms and see if they exhibit transitions, and if Cho- 
logaster is traversing the slow developmental road to Amblyopsis. 
Allowing all characters embraced in the general structure of the 
skeleton, brain, scales, fins, etc., as ordinal, and common to both 
Cyprinodontes and Heteropygii, we will recapitulate only such as 
can be considered of family and generic value in the two groups. 
CYPRINODONTES. CHOLOGASTER. TYPHLICHTHYS. AMBLYOPSIS. 
Surface feeders. In part. Unknown. Partially. 
Intestine. In mera Moderately pag Soaps The same. 
long anion convo- a ong wi two 
juted, in others 
ceti miiko vo iy 
Stomach § pylor- In most, if not Stomach well gji pere a with The same. 
ic appendages. an stomach not defined, cœ- pyloric ap- 
ell defined cal, with two pos ageon 
from intestine pyloric ap- each side. 
and without ap- pendages n 
each side. 
Viviparous. Many genera. Probably. Probably. ie doubted- 
Ovary. \ Single in vivipa- Single and Single and a same. 
rous genera* placed behind placen at do 
and placed by the sto! mach. ach. 
oa side of in- 
e 
and rapers in 
. > — ovary is also single in other genera of viviparous fishes belonging to distinct 
