46 ORIGIN OF THE BLIND FISHES. 



blyopsis and Typhlichthys by the presence of eyes, the absence of 

 papillary ridges on the head and body, and by the longer intestine 

 and double the number of pyloric appendages, as well as by the 

 position of the ovary ; and agrees with Typhlichthys by the ab- 

 sence of ventral fins. Amblyopsis and Typhlichthys are nearly 

 colorless, while Chologaster Agassizii is of a brownish color similar 

 to many of the minnows, and C. cornutus is brownish j'ellow, with 

 dark, longitudinal bands. 



Among the most interesting points in the history of this genus 

 is the fact of its occurring in two widely different localities, C. 

 Agassizii having been found in a well, in the same vicinity (proba- 

 bly in the same well) with a specimen of Typhlichthys, and 

 undoubtedly belonging to the same subterranean fauna west of the 

 Appalachian ridge, while C. cornutus belongs to the southern coast 

 fauna of the eastern side of that mountain chain, and is thus far 

 the only species of the family known beyond the limits of the great 

 subterranean region of the United States. 



Having now given an outline of the structure, habits and distri- 

 bution of the four species belonging to the family, and recapitu- 

 lated the known facts, we are better able to consider the bearings 

 of the peculiar adaptation of the blind fishes, in the Mammoth 

 and other caves, to the circumstances under which they exist. 



Prof. Cope in stating, in his account of the blind fish of the 

 Wyandotte Cave, "that the projecting under jaw and upward di- 

 rection of the mouth renders it easy for the fish to feed at the sur- 

 face of the water, where it must obtain much of its food," suggests 

 that : - 



"This structure also probably explains the fact of its being the 

 sole representative of the fishes in subterranean waters. No doubt 

 many other forms were carried into the caverns since the waters 

 first found their way there, but most of them were like those of 

 our present rivers, deep water or bottom i'eeders. Such fishes 

 would starve in a cave river, where much of the food is carried to 



them on the surface of the stream The shore minnows 



are their nearest allies, and many of them have the upturned 



mouth and flat head Fishes of this, or a similar famity, 



enclosed in subterranean waters ages ago, would be more likely to 

 live than those of the other, and the darkness would be very apt 

 to be the cause of the atrophy of the organs of sight seen in the 

 Amblyopsis." 



This suggestion was undoubtedly hastily made by Prof. Cope 

 when writing the letter which was printed in the "Indianapolis 



