384 REPORT OF THE COMMISSIONER OF FISHERIES. 
Cut 10 indicates the probable relationship of the species. The 
ancestry of the blind fishes is unknown.“ At first the group divided 
into 2, those with and those without ventral fins. Zroglichthys prob- 
ably entered the caves first, for its eyes have degenerated farther than 
any of the species. Amblyopsis and Typhlichthys probably entered 
about the same time. Chologaster agassizii has only recently entered 
caves, C. papilliferus is found only in cave springs in southern IIli- 
nois, and C. cornutus occurs in the southeastern United States in open 
waters. 
Troglichthys Typhilichthys C. agassizii C. papilliferus C. cornutus Amblyopsis 
Chologlaster 
Entered cave 
Entered cave 
Entered cave 
Ventrals abjsent Ventrals present 
Cut 10.—Diagram indicating probable phylogeny of the Amblyopside. 
KEY TO THE GENERA OF AMBLYOPSID. 
a. Eyes quite well developed; body more or less colored; ventral fins obsolete; pylo- 
TIC COeCar4. 4 he ee cee oe eee ee ee eee Chologaster. 
aa. Eyes rudimentary and concealed beneath the skin; body colorless; pyloric ceca 
2 (occasionally 3 in Amblyopsis). 
b. Ventral fins absent. 
ce No scleral cartilages presents...5. 2---eeeee ose eee ee eee Pyphlichthys. 
cc. Wuaree’scleralicartilaces presents. sso saeeeee see eee eee eee Troglichthys. 
bb. Ventral fins, present 2=- 22 S26 so aoe ee see eee ere ae ere Amblyopsis. 
aRigenmann, Science, N. §., 1899, LX, 282. 
