Trans. N. V. Ac. Set. ^^ Dec. 12, 



of these may reach 200 or 300 feet below the Ohio and Green Rivers. 

 There is evidence, from borings in the Delta of the Mississippi, etc., 

 that the continent was formerly more elevated, standing 500 to 600 

 feet higher at New Orleans than at present ; the drainage was much 

 freer, the Mississippi being a free flowing stream, as well as the Ohio 

 and other tributaries. Borings have been sunk in the present trough of 

 the Ohio river, to a depth of over 100 feet below its present bottom, 

 without reaching the true bottom ot the trough, the ancient bed of the 

 river, which is perhaps from 100 to 2co feet further down. 



Evidences of the same elevation of the continent were observed in 

 caves on an island in Lake Erie. Long stalactites projected from the 

 roof of a gallery whose end was ordinarily filled with water at the 

 present level of the lake. At times a strong and steady wind has blown 

 down the level of the lake and partially drained this gallery ; but even 

 then a guide, John Brown, resident on the island, has swum through 

 the gallery and found the stalactites projecting from the roof as far as 

 he could go. 



In regard to the origin of the blind animals, the view of Prof. Cope is 

 probably correct, that they have been derived from the degeneracy of 

 ancestors that once had perfect eyes. No fish is formed with poor eyes ; 

 but any organ may be atrophied by disuse, with consequent feeble flow 

 of blood, decreased nutrition, and inevitable shrinking of important parts. 

 An analogy is shown in a coinparison of the jaws of prehistoric and 

 modern men. At present our " wisdom teeth " are useless, there is 

 no room for them in the shortened under-jaw ; our food being softened 

 by cooking, cut up, and boneless, requires less vigorous mastication ; 

 and from disuse, and the consequently insufficient development, these 

 teeth often speedily fall away. In the prehistoric man, on the contrary, 

 the jaws were longer, roomier, supplied with more teeth — the " wisdom 

 teeth " being well developed and kept in strength by constant use on 

 coarse and rough food. The absence of the well-known stimulation 

 produced by light, from the dark waters within the Mammoth Cave, has 

 in the same way resulted in the atrophy of the organs of sight. 



Mr. Stevens remarked in confirmation of this view, on the observa- 

 tion, first announced by Dr. Tellkampf, that the old fish found in the 

 Cave have only rudimentai^y eyes, while in the young the eyes are simply 

 imperfect, /. e., the conditions tend to produce a reversion. 



Dr. I. P. Trimble referred to his visits to the Mammoth Cave and 

 its vicinity, the absence of fatigue in traveling within the Cave, and the 

 occurrence of bats clinging to the walls at a point three-quarters of a 

 mile from the entrance. He inquired concerning the condition of the 

 eyes in the bats and crickets within the Cave. 



Mr. Stevens replied that both species had eyes, externally and 



