ASSOCIATED FOSSIL MAMMALIA. 233 



that E. Golumbi 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 evi- 

 dence of Megatherium having ranged beyond the maritime 

 portion of Georgia and South Carolina. Mylodon Harlani 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 Fauna of Nebraska, nor 

 in the Pliocene Fauna 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 men- 

 tioned, both an Elephant and Mastodon occur. 1 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. Anchiterium) , is eqiially remark- 

 able, 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 conti- 

 nuity of continents which are now severed by wide oceans. 



Of two asserted facts, which it was of the utmost import- 

 ance to determine with accuracy, one appears to have been 

 clearly established : namely, that the extinct Edentate and 

 Proboscidean Fauna 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 freshwater deposit on the 

 right bank of the Niagara, near the Falls. The Drift between 

 Lakes Erie and Ontario was inferred to be of much higher 

 antiqiiity than the gravel containing the bones of Mastodon 

 at the Falls. 2 



But the evidence in support of the inference that the same 

 extinct Fauna existed before the deposition of the ' Drift,' in 

 the same region, is not equally conclusive. It has been 



1 Proceed. Acad. Nat. Scien. Philad. 

 1858, p. 20, etseq. 



2 Proceed. Geol. Soc. 1843, vol. iv. p. 

 36. These results have been confirmed 



by the later observations of Professor 

 Ramsay. Quartly. Journ. Geol. Soc. 

 1859, vol. xv. p. 214. 



