292 PROBOSCIDIA. 
linear lines are well displayed at the fractured surface of 
this end, figured atc. The transverse section of this tusk 
(fig. 101, 4) gives an irregular oval figure, one side being less 
convex than the other; and on the lower half of the less 
convex (outer) side of the tusk, faint traces may be distin- 
guished of longitudinal grooves, about a line in breadth: 
the slender subcentral canal is nearer the lower than the 
upper surface of the tusk. In all these characters, the 
fragment in question agrees with a similar fragment of a 
tusk, ten inches in length, obtained from the miocene, or 
older pliocene tertiary deposits at Eppelsheim, and now in 
the collection of the Earl of Enniskillen ; which specimen 
Dr. Kaup has determined to belong to the lower jaw of 
his Mastodon longirostris, the Mastodon angustidens of 
Cuvier. 
The earliest observation of this striking character of in- 
ferior tusks, which distinguishes the genus Mastodon from 
Elephas, appears to have been made by Dr. Godman, in 
1829,* upon a mutilated lower jaw of a young Mastodon 
giganteus, obtained, I believe, from tertiary deposits in 
Orange County, United States, and at that period in 
Peale’s Museum, New York. The symphysis of this jaw 
was entire, and contained two short tusks, from four to 
six inches in length, projecting straight forwards from the 
extremity of that part of the jaw. As the lower jaws of 
the mature American Mastodons which were at that time 
known to science, offered, like those of the species of 
Elephant, no trace of tusks, Dr. Godman described his 
specimen as belonging to an extinct animal of a new 
genus, for which he proposed the name of Tetracaulodon. 
Mr. Cooper of New York, however, “suggested the opinion 
that the Tetracaulodon was nothing but the young of the 
* Transactions of the American Philosophical Society, vol. iii, N.S. p. 478. 
