62 
ORIGINAL ARTICLES. 
phants occur in the States east of tlie Mississippi, those found to the 
north of the Apalachians, belong chiefly to E. primigenius; and 
that E. Columbi is the predominant, although not the sole species, 
in the littoral States south of the chain, as far north as Newbern 
near Cape Hattras. Huge extinct Edentata accompany both; but 
Dr. Leidy has found no authentic evidence of Megatherium having 
ranged beyond the maritime portion of Georgia and South Carolina. 
Myludon JELarlani is said to occur north and south of the chain. 
Knowing, as we do, what an important feature the large extinct 
Edentata constitute in the Newer Pliocene fauna of the littoral 
regions both of North and South America and of the interior of the 
United States, it is not a little remarkable, that, neither in the 
Lower Miocene Eauna of Nebraska, nor in the Pliocene Eauna of 
Niobrara, both of which have been so ably investigated by Leidy, 
has a single Edentate form been discovered, although in the latter, 
as already mentioned, both an Elephant and Mastodon occur.* The 
great number of Equine forms found in the Niobrara deposit, coupled 
with the antiquity of some of the genera to which they have been 
referred ( e . g. Anchitheruiii) is equally remarkable, and suggestive of 
reflexion, with reference to some of the great problems which now 
occupy naturalists, regarding the derivation and spread of species, 
and the former continuity of continents which are now severed by 
wide oceans. 
Of two asserted facts, which it was of the utmost importance to 
determine with accuracy, one appears to have been clearly established: 
namely, that the extinct Edentate and Proboscidian Eauna of the 
United States, existed long after the deposition of the northern drift. 
This was put beyond doubt by Lyell many years ago; the bones of 
Mastodon Ohioticus , which are commonly associated with E. primige- 
nius , were found along with existing shells in Tennessee in a swamp 
“ in a cavity of the boulder formation, so that the animal must have 
“ sunk after the period of the drift, when a shallow pond fed by 
“ springs, was inhabited by the same species of freshwater mollusca 
“‘ as now live on the spot.” The same result was arrived at in the 
fresh-water deposit on the right bank of the Niagara, near thb Palls. 
The drift between Lakes Erie and Ontario was inferred to be of 
much higher antiquity than the gravel containing the bones of Mas¬ 
todon at the Ealls.f 
But the evidence in support of the inference that the same extinct 
Eauna existed before the deposition of the ‘ drift,’ in the same region, 
is not equally conclusive. It has been asserted that Dr. W. M. 
Dickeson discovered in Mississippi, east of Natchez, remains of Mega- 
lonyx , Mylodon , Mastodon , Equus Americanus (Leid.), Bootherium , 
* Proceed. Acad. Nat. Scien. Philad. 1858, p. 20, et seq. 
t Proceed. Geol. Soc. 1843, Yol. 4, p. 36. These results have been confirmed 
by the later observations of Professor Ramsay. Quartly. Journ. Geol. Soc. 1859, 
Vol. xv. p. 214. 
