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belonging to different families, and described the species 

 making up the family of Heteropygii, which contains the 

 two species of blind fishes of the Mammoth Cave and 

 two other species that have eyes. Giving a statement of 

 the various theories relating to the non-development of 

 eyes in the blind fishes of the cave, he asked why is it 

 necessary to assume that because fishes are living in streams 

 where there is little or no light, that it is the cause of the 

 non-development of the eye and the development of other 

 parts and organs? If this be the cause, how is it that the 

 Chologaster from the well in Tennessee, or the "mud- 

 fish" of the Mammoth Cave are found with eyes ? Why* 

 should not the same cause make them blind if it made the 

 Amblyopsis and Typhlichthys blind? Is not the fact, 

 pointed out by Prof. Wyman, that the optic lobes are as 

 well developed in Amblyopsis as in allied fishes with 

 perfect eyas, and, I may add, as well developed as those 

 of Chologaster cornutus, an argument in favor of the the- 

 ory that the fishes were always blind and that they have 

 not become so from the circumstances under which they 

 exist? If the lattetwere the case and the fishes have 

 become blind from the want of use of the eyes, why are 

 not the optic lobes also atrophied, as is known to be the 

 case when other animals lose their sight? I know that 

 many will answer at once that Amblyopsis and Typhlich- 

 thys have gone on further in the development and retarda- 

 tion of the characters best adapting them to their subter- 

 ranean life, and that Chologaster is a very interesting 

 transitionary form between the open water Cyprinodoutes 

 and the subterranean blindfishes. But is not this assump- 

 tion answered by the fact that Chologaster has every char- 

 acter necessary to place it in the same family with Ambly- 

 opsis and Typhlichthys, while it is as distinctly and widely 

 removed from the Cyprinodontes as are the two blind 

 genera mentioned? 



