THE TUSKS. . 89 



the genus Eleplias; a distinction which M. De Blainville, Dr. Falconer, a Distinc- 

 tion of 

 and others, have been willing to pass over. But hitherto, so far as we Mastodon 



and 



know, the existence of this part in the elephant has not been discovered ; E i ep hant. 



while it is perfectly established in regard to the principal species of 



Mastodon, the Mastodon Giganteus, and Mastodon Angustidens. So long 



as this fact remains uncontroverted, we should consider it, taken in 



connection with other facts, as forming an impassable boundary between 



the two families. 



This tush (Plate XX.) is eleven inches long, five and a half in circum- Length. 



ference, and two in diameter at the base ; being longer by an inch than the 



cast of a similar one in the collection of the American Philosophical Society, 



which was taken from the specimen originally described by Dr.. Grodman, 



and disinterred by Mr. Archibald Crawford, near Newburgh. The direction Direction. 



of our tusk is forwards and downwards, forming an angle with a horizontal 



line of about 45°. It has a cavity an inch and a half in diameter at the 



internal extremity, the thickness of the edge being one-fourth of an inch : 



this cavity is of a conical form, and two inches deep. The rest of the tusk structure. 



appears to be solid. The anterior extremity is rounded, and about an inch 



in diameter ; on one side it has been worn away to the extent of four 



inches. The worn surface is smooth at its extremity only, the rest being 



quite rough ; the depth of the external layer is exposed in this abrasion, 



and exhibits the thickness of an eighth of an inch. Near the posterior or 



internal extremity are seen a number of circles to the amount of ten 



or eleven, extending from the base, two to three inches forward, and 



occupying that part which lay in the socket. The surface of the tusk 



generally exhibits longitudinal stria?, in some of which cracks begin to 



appear from desiccation. These stria? are distant from each other from 

 12 



