340 ON THE FOSSIL BONES OF PACHYDERMATOUS QUADRUPEDS. 



Mr. Peale has not given the length of the skull of his skeleton ; but 

 to judge of it by the figures, it must be nearly equal to 1,136. The 

 portion which is in the cabinet of M. Camper (plate 20) measures 

 0,455 from the front of the tooth with six denticuli to the posterior 

 edge of the pterygoid apophyses. Calculating its entire length on the 

 proportions indicated by the figures of Mr. Feale, it should be 0,91. 

 Mr. Peale's mastodon being supposed to be ten feet high, this portion 

 of the head must have belonged to an animal of eight. An elephant 

 eight feet higli, measures but 0,8 from the alveolar edge to the 

 occipital condj^les. Thus the head of the mastodon is a little longer, in 

 proportion to the height of its body, than that of the elephant. 



4. The Tusks. 



The front of the lower jaw, when deprived of its teeth and contracted, 

 affords a sufficient indication that there must have been some teeth in 

 the upper jaw, protruding from the mouth, as is observable in the ele- 

 phant and the rcsemarus. 



This is further confirmed by the tusks which are so frequently found 

 with the jaws of the mastodon : this was at first the opinion enter- 

 tained by Camper, previous to his falling into the error I have just re- 

 futed. 



Strictly speaking, however, it was possible that the tusks and the 

 teeth armed with denticuli might have belonged to separate animals, 

 and Daubenton had adopted this conjectui'e. 



The reasons in support of this opinion must have increased, when it 

 was ascertained that the real molares of elephants have been found in 

 the same places. 



Mr. Peale was the first to supply incontestible proofs of the masto- 

 don's having tusks, by discovering a skull with the alveoli still extant, 

 and with its molares in a good state of preservation. 



They are imbedded in' the incisive bone, like those of elephants. 

 They are composed, like the latter, of an ivory, the grain of which pre- 

 sents the appeara.nce of curvilinear lozenges. It is almost impossible to 

 distinguish a piece of elephant's ivory from that of the ivory of the 

 mastodon. 



I am justified in this observation by a tusk of the latter species, which 

 is at the present moment lying on my table. It was brought to our 

 Museum from the west of the Alleghanies, with the portion of the lower 

 jaw to which I have so often alluded. 



Mr. Peale, indeed, gives a somewhat different account of the tusks 

 of his skeleton : — " A transverse section of the tusk of an elephant," 

 says tliis learned man, " is always oval ; that of the mastodon is per- 

 fectly round. The ivory of the former is uniform ; the latter presents 

 us with two distinct substancss ; the interna,! has the texture of ivory, 

 but its consistency is much less : the exterior surface has not that 

 texture, is much harder than ivory, and forms a thick envelope to the 

 whole tusk." — (Disquisition on the Mammoth, p. 50). 



But these distinctions are not accurate. 



1st. The tusks of the elephant are ofceu more or less round; on the 

 contrary, that of the mastodon at present under my observation is 

 elliptic. 



