258 Prof. Rogers's Address before the 



tion which it deserves. Was it the recession of the tepid waters of 

 the Gulf Stream driven eastward by a partial elevation, possibly of the 

 Florida peninsula, or was it connected with the incursion southward of 

 a vast body of icy waters from the north, the same which in the opin- 

 ion of some was concerned in the dispersion of the drift, or was it the 

 result of some more inscrutable agency ? 



The post pleiocene deposit on the Neuse River, has been described 

 by Mr. Conrad* as consisting of a shallow stratum, in which the shells 

 with two exceptions, are such as now exist on our southern Atlan- 

 tic coast and in the Gulf of Mexico, the Gnathodon cuneatus being 

 one of the species. Mixed with these shells are the bones and teeth of 

 extinct land animals, such as those of an elephant^ a species of liorse^ 

 and the Mastodon giganteum. 



Another small tract of this modern tertiary has recently been de- 

 scribed by Mr. J. Hamilton Couper,t as occupying a part of the sea- 

 coast of Georgia between the Altamaha and Turtle Rivers. Asso- 

 ciated with shells belonging to species now inhabiting the neighboring 

 coast, are the remains of the Megatherium^ Mastodon giganteum, ele- 

 phant, hippopotamus, horse, and hison, all of the four latter belonging 

 it is believed to extinct species. 



Mr. Lyell in an instructive paper on the Mastodon giganteum and 

 other mammalian fossil remains found at several localities in the Uni- 

 ted States,^ mentions the occurrence in Georgia of that curious Pro- 

 boscidean described by Owen, the Mylodon. He also informs us that 

 Mr. Darwin found the mastodon, horse, megatherium, megalonyx, and 

 mylodon, in Patagonia and contiguous districts of South America, and 

 occupying a more recent horizon than ' certain post pleiocene strata ; 

 and some of these extinct animals Mr. Darwin ascertained to be more 

 modern than the drift of Patagonia. It may be remembered that sev- 

 eral years ago, in a report to the British Association, he announced the 

 fact, that the mastodon remains in this country lie invariably above the 

 diluvian, a position equivalent, it would seem, to that which they oc- 

 cupy in South America, and I draw from this the inference, that they 

 were not overwhelmed by any sudden catastrophe, but disappeared 

 gradually, being probably overtaken by a progressive chilling of the 

 climate. It is correctly urged by Mr. Lyell, _that having lived after 

 the deposition of the northern drift, their extinction cannot have pro- 

 ceeded from any coldness of temperature such as he conceives coin- 



* Bulletin of National Institute. 



t Proceedings Geol. See. London, No. 92. % Ibid. 



