48 
OKIGIN OF THE BLIND FISHES. 
as well developed as those of Ohologaster cornutus^ an argument 
ill 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 
Cliologaster 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 moment, 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. 
Unkno^Yn. Partially. 
The same. 
Intestine. 
Stomach cf pylor- 
ic appendages. 
Viviparous. 
Ovary. 
In many genera 
long and convo- 
luted, in othei’s 
short and with 
single turn. 
In most, if not 
all, stomach not 
well defined 
fr o m intestine 
and without ap- 
pendages. 
Many genera. 
Single in vivipa- 
rous genera* 
and placed by 
the side of in- 
testine in some 
and posterior in 
others. 
Moderately 
long with two 
turns. 
Shorter Avith two 
turns. 
The same. 
Stomach well 
defined, coe- 
cal, with two 
pyloric ap- 
p end ages on 
each side. 
The same, with 
one pyloric ap- 
pendage on 
each side. 
The same. 
Probably. 
Probably. 
Undoubted- 
ly- 
Single and 
placed behind 
the stomach. 
Single and 
placed at side 
of stomach. 
The same. 
♦The ovary is also single in other genera of viviparous fishes belonging to distinct 
orders. 
