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clence that light is not necessary for the existence of col- 

 oration in animals, for here in total darkness is this most 

 beautifully tinted fish. 



From the present knowledge of the fauna of onr rivers 

 it can only be assumed, without a fact in favor of such an 

 assumption, that the Chologaster is a later comer into the 

 subterranean streams than its blind and colorless cousins, 

 and it cannot now be maintained with any reason that the 

 supposed peculiar adaptability to surface feeding was the 

 cause of the survival of the blind fishes of the caves, and 

 the want of the structure adapting the fish to surface feed- 

 ing the reason that other forms did not survive; for we 

 have in Chologaster a fish with just the same structure of 

 mouth as in Amblyopsis and Typhlichthys, provided with 

 an equally large air bladder (if that can be considered as 

 having anything to do with surface habits), and yet living 

 always at the bottom of the water. 



Yet that many species enter the cave from the outside 

 waters is proved by the collection of the following species 

 of fishes in the same waters with the blind fishes and the 

 Chologaster : — 



Two specimens of Amiurus cat us, half grown ; one 

 specimen of Vranidea (sp. ?), very large ; one specimen 

 each, of full size, of two species of Cyprinoids not yet 

 determined, but, as in the case of the cat-fish and bull- 

 head, of the same species as those collected in the Green 

 River just outside of the cave. All five of these speci- 

 mens were as highly colored and had their eyes as perfect 

 as their kin in the Green River. They were all in good 

 condition, and when captured were in every way appar- 

 ently as well off as if in daylight. 



A large number of insects, small crustaceans, etc., were 

 obtained in the cave, and a few species of plants of the 

 lower forms were collected. The other living specimens 



