384 



REPOET OF THE COMMISSIONER OF FISHERIES. 



Cut 10 indicates the probable relationship of the species. The 

 ancestry of the blind lishes is unknown." At first the group divided 

 into 2, those with and those 'without ventral fins. TrogllcJithys prob- 

 ably entered the caves first, for its eyes have degenerated farther than 

 any of the species. Amhlyopsls and TyphlicJithys probabl}^ entered 

 about the same time. Chologaster agassizli has only recently entered 

 caves, O. j^dJ^'Miferiis is found only in cave springs in southern Illi- 

 nois, and C. cornutus occurs in the southeastern United States in open 

 waters. 



TrogUchthys Typlilichthys 



C. agassizii 



C. papiUilcrus 



Amblyopsis 



Cut 10. — Diagram indicating probable pliylogeny of tlie Amblyopsidse. 



KEY TO THE GENERA OF AMBLYOPSID.E. 



a. Eyes quite well developed; body more or less colored; ventral fins obsolete; pylo- 

 ric coeca 4 Chologaster. 



aa. Eyes rudimentary and concealed beneath the skin; body colorless; pyloric coeca 

 2 (occasionally 3 in Anihh/opsis) . 

 h. Ventral fins absent. 



c. No scleral cartilages present Typhlichihys. 



cc. Large scleral cartilages present TroglichOiys. 



bb. Ventral fins present Amblyopsis. 



«Eigenmann, Science, N. S., 1899, IX, 282. 



