338 ON THE FOSSIL BONKS OK PACHYDERMATOUS QUADllUPEDS. 



It thereby appeared, 1st, that this animal, like the elephant and the 

 rosemarus, had neither incisors nor canine teeth in the lower jaw; 

 2ndly, that its lower jaw terminates in front in a point, intersected by a 

 species of canal ; which is also the case with the elephant and the rose- 

 marus ; 3dly, that its posterior angle, though obtuse, is well defined, 

 and not rounded circularly, as it is in the elephant. 



The condyle, the most characteristic part of the lower jaw, was there 

 mutilated ; but an idea of it may be formed by an examination of plate 

 21, fig. 6, for which I am indebted to the kindness of Mr. Peale. 

 We have there a front view of the jaw of the mastodon, probably con- 

 trasted with that of the elephant of fig. 7. 



It may be observed that the condyle differs in little from that of the 

 elephant ; which, taken with the formation of the teeth, is an additional 

 proof that the animal was not carnivorous. The whole of the ascend- 

 ing part is high in proportion, and the coronoid apophysis rises to the 

 level of the condyle, while in the elephant it is much lower. The 

 longitudinal part is less elevated in proportion to its length, but it is quite 

 as much bumped, particularly behind. 



The lower jaw of Mr. Peale's skeleton is 2^ 10^' (English) long, 

 and weighs 63 pounds. The mutilated half (plate 22) measures from 

 its point to some distance behind the molar (from a to b, figs. 1 and 2) 

 0,54, which leads me to think that when entire, it was the larger of the 

 two. The height of its dental part is 0,175, and its thickness 0,114 ; 

 it weighs twenty-six pounds three ounces. That of an elephant of 8^ is 

 only 0,65 in length. 



But to have a more accurate knowledge of the anterior part of this 

 jaw, we must consult plate 21, fig. 5, which is copied from that of 

 Mr. Mitchell. 



We may there observe, that the point is more contracted and pro- 

 longed in front than is the case in any other specimens which are mu- 

 tilated in this fragile part. This character may easily serve to dis- 

 tinguish the jaw of a mastodon, even without its teeth, from those of 

 the fossil elephant. 



3. The Skull. 



The descriptions of Michaelis and Camper first brought us ac- 

 quainted with the fragment represented in plate 20, figs. 1, 2, and 5, 

 with which the piece of fig. 3, which must have belonged to it, corre- 

 sponds ; so that a, b, fig. 3, shall touch a^ b', fig. 2, and that the 

 tooth A of fig. 3 shall be the congeneric of the tooth A, fig. 2. Thus 

 B is the molar apophysis of the maxillary bone ; C C, the pterygoid 

 apophysis of the palatine bones ; E E, the suture separating the palatine 

 and maxillary bones, &c. 



I have remarked that Michaelis and Camper considered this spe- 

 cimen in an inverse sense, taking the posterior extremity for the ante- 

 rior, and the palatine for the intermaxillary bones. 



And yet there were sufficient reasons to allege against their opinion; 

 1st. the anterior jaw bones must then have been larger than the 

 posterior ; the contrary of which obtains in all herbivorous animals, 

 and even in the lower jaw of this animal itself; 2nd, they must have 

 been less worn, which is not less contrary to reason and analogy ; 3rd, 

 there would then have been no incisive aperture, &c. 



