202 The Scyphophori, Haplomi, and Xenomi 
of Virginia, thence southward through swamps and rice-fields 
to Okefinokee Swamp in northern Florida. It is a small fish, 
less than two inches long, striped with black, and with the habit 
of a top-minnow. Other species of Chologaster, possessing 
eyes and color, but provided also with tactile papilla, are found 
in cave springs in Tennessee and southern IIlinois. 
From Chologaster is directly descended the small blindfish 
Typhlichthys subterraneus of the caves of the Subcarboniferous 
limestone rocks of southern Indiana and southward to northern 
Alabama. As in Chologaster, the ventral fins are wanting. 
The eyes, present in the young, become defective and useless 
in the adult, when they are almost hidden by other tissues. 
The different parts of the eye are all more or less incomplete, 
being without function. The structure of the eye has been 
described in much detail in several papers by Dr. Carl H. Eigen- 
Fic. 162.—Blind Cave-fish, — sie sei Girard. Mammoth Cave, 
Kentucky. 
mann. As to the cause of the loss of eyesight two chief 
theories exist—the Lamarckian theory of the inheritance in the 
species of the results of disuse in the individual and the 
Weissmannian doctrine that the loss of sight is a result of 
panmixia or cessation of selection. This may be extended 
to cover reversal of selection, as in the depths of the great 
caves the fish without eyes would be at some slight advantage. 
Dr. Eigenmann inclines to the Lamarckian doctrine, but the 
evidence brought forward fails to convince the present writer 
that results of individual use or disuse ever become hered- 
itary or that they are ever incorporated in the characters 
of a species. In the caves of southern Missouri is an inde- 
pendent case of similar degradation. Troglichthys rose, the 
blindfish of this region, has the eye in a different phase of 
degeneration. It is thought to be separately descended from 
