i88l. 65 Trans. N. Y. Ac. Sci. 



Putnam has shown that the differences between the blind fish 

 (A. sfelaeus) and their nearest living congeners are much more than 

 in respect to mere color of skin and power of vision. Whether the 

 internal anatomical differences pn which he reasonably lays much stress 

 can be proven to be a natural result of the external conditions imposed 

 by cave life, is a question which, if settled at all, must be settled by 

 zoologists alone. Prof. A. S. Packard, jr., and Prof. E. D. Cope are as 

 pronounced in their opinion that the blind fish have been evolved from 

 fresh-water ancestors possessing good vision, as is Prof. Putnam in the 

 opinion that their ancestry were denizens cf salt or brackish water, with 

 which he believes that the cave was supplied at a time when this region 

 was a salt or brackish water estuarv. Prof. Putnam therefore con- 

 cludes that the blindness of these fish is in no respect a consequence of 



subterranean life. 



Discussion. 



Mr. Britton inquired whether any flora existed in the cave. 



Mr. Stevens replied that, so far as he was aware, no kind of vege- 

 tation had ever been found within it. 



Dr. Newberry remarked on the geology of the region adjacent to 

 the Mammoth Cave. The limestone beds of this high table-land are 

 jointed in the manner common to rocks, apparently by some sort of 

 polarisation, producing fissures which run in a north and south, and an 

 east and west, direction. The plateau is about 500 feet above the 

 drainage, part of the drainage passing into the Green River, and part 

 into the Ohio. No streams occur on the surface and the drainage is 

 quite gradual. At the angle between these two rivers several streams 

 are seen, bursting out of the cliffs at various heights above the Ohio ; 

 they are, so to speak, subterranean sewers, representing the under- 

 ground drainage of the country ; at one point three such streams pour- 

 ing out of the rock form very beautiful cascades ; and near Sandusky 

 a full grown river flows out of the cliff of cavernous limestone. The 

 beds consist of lower carboniferous limestone, with sandy layers beneath. 

 In the vicinity occur portions of the great " blue grass region," one ot 

 the oldest parts of the continent, once an extensive highland, forming 

 an island in the sea. Around this, rims of sediments were deposited, 

 consisting of sandstones and limestones ; while on the other hand, the 

 continuous process of erosion, during the lapse of a vast period, re- 

 moved the material of the table-land within, and converted it into a 

 broad depression or basin, the " blue grass region," above which the 

 present plateau of the encircling sediments now rises to a height of 500 

 feet. 



The erosion of the joints in this plateau has resulted in the forma- 

 tion of the pits described by Mr. Stevens, but it is probable that some 



