DAKOTA AND NEBRASKA. 251 



species, in association with those of nipparion and Eleplias, at the head of the Loup 

 Fork branch of the Platte River, between that point and the Niobrara Eiver, and in 

 the course of the latter. The remains of M<.istodon mirificus are attributed b_y Dr. 

 Hayden to the uppermost bed of the pliocene tertiary, or bed F of his section of the 

 tertiary deposits of Nebraska and Dakota. 



ELEPHAS. 



Fossil i-emains of Elephants have been discovered throughout the continent of 

 North America, frequently in association with those of Mastodon americanus. They 

 are much less abundant than those of the latter, less complete, and generally less 

 well-preserved. The Elephant, though a cotemporary of the Mastodon, probably pre- 

 ceded it in time, and probably ceased to exist long before the latter. Indeed, the 

 remains of the North American Elephant which have been discovered, with a few 

 exceptions, consist of teeth, and, while many complete skeletons of the Mastodon have 

 been found, to this day we know but little of the skeleton of our Elephant. 



From the character of the molar teeth, most naturalists of authority have regarded 

 the remains of the North American Elephant as having belonged to the same species 

 as the Mammoth, or Elejihas primigenius of Northern Asia and Europe. 



Among the fossil teeth of the American Elephant two varieties have been observed; 

 the ordinary one, in which the constituent divisions or lobes are comparatively thin 

 and numerous ; and the other, in which the lobes are coarser, less numerous, with 

 thicker and more crimped enamel, and more widely separated by cementum. Dr. 

 -Harlan thought it probable that these two varieties of teeth indicated different 

 species,* and this opinion is more decidedly expressed by Dr. Falconer, who had more 

 favorable opportunities for investigating the characters of the great proboscideans, 

 both living and extinct, than any other naturalist. Dr. Falconer regards the thin- 

 lobed variety of fossil teeth of this continent as belonging to Elephas primigenius, 

 while the coarser-lobed variety he has referred to a different species, with the name 

 of Elephas Golumhi. 



Though it is not improbable that the Eleplias primigenius may have ranged through 

 the high northern latitudes of America and Asia including its jieninsula Europe, 

 and may even have extended southwardly throughout the continent of North 

 America, such a wide range of distribution of a species of mumraal is unusual. While 

 I am disposed to view the remains of the Elephant found in the frozen cliffs of 

 Escholtz Bay in northern Alaska, and bordering closely on Asia, as those o? Ehplias 

 primigenius, I hold the opinion that most of the remains found throughout North 

 America, and usually referred by authors to the latter, really pertain to a peculiar 



*Joui-. Ac. Nat. Scl. iii, 1823, 67; Med. Pbys. Res. 1835, 3C1. 



