252 ON THE EXTINCT MAMMALIA OF 



species. This opinion I think is sustained by sufficient anatomical evidence. Dr. 

 Falconer observes that " there is one peculiarity in the molars of the North American 

 Mammoth, which is so constant that I believe in most instances, by means of it, they 

 can be discriminated in a mixed collection of European, Asiatic and American speci- 

 mens, — namely, that the ridges and their constituent elements are more attenuated 

 and condensed."* He however adds : " But I do not regard it as indicating more 

 than a slight geographical variety, as the other characters, such as the form of the 

 lower jaw, &c., remain constant to the true Mammoth type." 



The anterior portion of a lower jaw, found at Jackson, Ohio, and described and 

 figured by an anonymous writer in the American Journal of Science, vol. xxxiv, for 

 1838, and corresponding portions of two jaws found at Burlington Heights, near 

 Hamilton, at the western extremity of Lake Ontario, described and figured by E. 

 Billings in the Canadian Naturalist, vol. viii, for 1863, exhibit decided peculiarities 

 distinguishing them from their homologues in Elephas jiTimigenius. In comparing 

 the figures of the front part of the lower jaws, in the works just mentioned, with 

 those of E. priviigenius in Cuvier's plates of the Ossemens Fossiles, we are struck 

 with the differences. The converging rami of the lower jaw, in the specimens above 

 indicated, with the prolonged narrow symphysis, and the deep narrow symphysial 

 gutter, would rather lead one to suppose our Elephant was the same as the living 

 Asiatic species than the extinct E. immigenius of Asia and Europe. 



Viewing the North American Elephant as distinct, I had adopted for it the name, 

 first proposed by Dekay, oi Elephas americanus, before I had noticed the account of 

 the lower jaw from Jackson, Ohio, which the author, for convenience in comparison, 

 refers to under the name of ElepJias Jacksoni, and which Mr. Billings has since called 

 Eueleplias Jacksoni, attributing the name to Briggs and Foster. 



It is not improbable that the teeth referred by Dr. Falconer to E. Gohimhi may 

 indicate a distinct species from the former, though at present I am not prepared to 

 view it as such, for the many specimens of fossil Elephant teeth I have had the 

 opportunity of examining appear to exhibit every gradation of character between the 

 extreme varieties. Nearly the same characters assigned to the teeth referred to E. 

 Columhi I had recognized in the fragment of a molar from the Niobrara Kiver, before 

 I had seen the account of the former, which induced me to refer the Niobrara fossil 

 to a species with the name of E. imi^erator. This, from its belonging to a special 

 geological fauna, may prove to be distinct, but, awaiting futui'e discovery, I am in- 

 clined to view it, together with E. Columbi, as belonging to the E. americantis. 



The gradation of characters assigned to the American variety of teeth of ^. primi- 

 genius and E. Columhi is illustrated by the following list of specimens preserved in 

 the Museum of the Academy : 



* Ou the Am. Fos. Elephant, in Nat. Hist. Rev. 1863, 66. 



