FOSSIL MAMMALIA. 75 



Among the fragments collected by Dombey in Peru, is a 

 considerable portion of the lower jaw. It terminates in front 

 by a sort of beak, like that of the elephant and mastodon, 

 which proves that, hke the two last, this animal had neither 

 incisors nor canines below. There were two teeth in this frag- 

 ment ; one had five pair of points, of which the hinder were 

 the shortest. The two first were joined in quadrilobe figures, 

 the two following were approaching to the same state; the two 

 last and the heel were untouched ; the external side was the 

 most worn, the internal most projecting. This must be the 

 case to make the teeth below correspond to those above. Be- 

 low, the external points form trefoils ; above, the internal. 

 This is the result of a general law in the herbivora. When 

 the two sides of the tooth do not resemble, they are placed in 

 contrary directions, in the two jaws. Thus, in the ruminantia, 

 the convexity of the crescents of the upper teeth is inside, and 

 outside in those below. 



From a palate, preserved in the British Museum, and which 

 belongs to this species, and not to the great mastodon, we find 

 that the upper molars diverge forward like those of the last 

 mentioned species. 



Analogy renders it probable, that the species of which we 

 are speaking, had tusks like that of the Ohio. Daubenton, 

 indeed, says that he could recognise ivory among the frag- 

 ments sent from the mines of Simorre. Two plates of ivory 

 were found by the Baron among the fragments sent by M. 

 Chouteau from Avary. But we want the direct proof, for no 

 tusk nor alveolus with molar adhering has yet been found. 



The lower jaw is certainly that of an animal with long tusks. 

 That from Peru is very like the one of the Ohio. It is, how- 

 ever, less high in proportion. Its lower edge is less rectilinear, 

 and its external surface more inflated. The foramina menti 

 are more advanced. The teeth of this mastodon are much 

 longer, in proportion, than they are broad, which induced the 

 Baron to give it the name he has done. 



