196 



Lebanon, Tennessee. This fish, which reaches a length 

 of nearly five inches, is of a delicate brownish tint, and 

 is provided with dark and well developed eyes. Five 

 specimens were secured by setting the seine over night 

 several times, and though every effort was made to cap- 

 ture them by ordinary methods of seining, it proved un- 

 successful, so shy and quick of movement is this singular 

 inhabitant of the dark waters of the cave. 



Its habits are in marked contrast to those of the blind 

 fishes, for it lives at the bottom of the stream, darting 

 with the utmost rapidity, and swimming rapidly by very 

 quick lateral motions of its whole body, seldom coming 

 near the surface, even in the aquarium, unless disturbed. 



The blind fishes on the contrary swim slowly about or 

 remain at rest near the surface of the water, and are very 

 readily seen and easily captured by a careful and quick 

 movement of the scoop net, though if, by means of the 

 peculiar tactile organs with which they are so liberally 

 supplied, they feel the least disturbance near them in the 

 water, they move off by a quick dart and then swim 

 slowly about ; occasionally they drop to the bottom for a 

 short time, but it is seldom that they are so seen. 



An interesting fact respecting the theory of the adapta- 

 bility of the color of an animal to its surroundings is 

 observable in the Chologaster ; they are so near the exact 

 color of the dark sand of the bottom of the river in the 

 cave that it is almost impossible to distinguish them as 

 they lie at rest, and yet this can hardly be supposed in 

 any way to add to their security, for as utter darkness 

 prevails they would be equally safe, in that respect, if 

 they had all the colors of the rainbow displayed on their 

 bodies, and then probably their principal enemy is the 

 large species of blind fish. 



This Chologaster also gives the most conclusive evi- 



