Trans. N. Y. Ac. Sez. ie 106 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 of the trough, the ancient bed of the 
river, which is perhaps from 100 to 200 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 astrong 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 comparison 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 rudimentary eyes, while in the young the eyes are simply 
imperfect, z. ¢., 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 
