DIVERGENCE AND CONVERGENCE IN FISHES. 63 



5. What has gone before concerning the changes in light, 

 heat and plant-growth in the cave in general applies to the water 

 in a cave except that the total content of the rivers of a cave will 

 change with comparative rapidity. With every freshet in epigean 

 rivers there is a corresponding freshet in the subterranean streams. 

 There must be some change in the temperature of the water in 

 caves though the change is not at all commensurate with the 

 changes in temperature in epigean rivers. No detailed records 

 of water temperatures are at hand. 



In an environment, such as that above described, all those dif- 

 ferences between related species which would strike the eye, such 

 as protective coloration, recognition marks, decorations of any 

 sort, etc., are absent and related species tend to look alike. 

 Amblyopsis and Typhlichthys look alike when of the same size, 

 and it was not until after a detailed examination of many speci- 

 mens that I could invariably distinguish Litcifitga and Sfygicola, 

 the Cuban blind fishes, from each other. There are two unre- 

 corded species of Typhlichthys, differing from the only known 

 species, subterraneus, in only a few inconspicuous respects. 



Typhlichthys subterraneus has been known chiefly from Mam- 

 moth cave, the type having come from a well at Bowling Green, 

 south of Mammoth Cave. I have repeatedly taken it at Glas- 

 gow, Kentucky. It has erroneously been recorded from Mis- 

 souri and Indiana, but is confined to the region south of the 

 Ohio and east of the Mississippi. 



A number of years ago a single specimen of Typhlichthys was 

 sent to Indiana University from Cory don, Ind., and it was referred 

 to snbtcrraneiis. Every endeavor to secure additional specimens 

 has so far failed. The Corydon specimen may here be described as 



Typhlichthys wyandotte Eigenmann, sp. nov.* 



The single specimen taken from north of the Ohio River, from a well 

 near Corydon, Indiana, differs slightly from those south of the Ohio, being 

 somewhat more slender. The Corydon specimen is 42 mm. in length from 

 the tip of the snout to the base of the caudal, and other measurements are 

 as follows : Head in length of body to base of caudal, 3% ; width of head 

 in length of body 6%, \% in its own length; distance from posterior 



* This specimen has been recorded as Typhlichthys subterraneus Eigenmann, 

 Proceedings Indiana Academy of Science, 1898 for 1897, 230 (Corydon, Indiana). 



