ON THE BONES OF THE MASTODON. 335 



Was this a tooth of six or four denticuli ? This is a question which 

 can only be decided by the discovery of some jaws of younger animals 

 than those of which we have just spoken. 



This young jaw demonstrates it to have been invariably the case, 

 that the great mastodon had successively at least four molares on each 

 side of his lower jaw ; and as we have no reason for not believing that 

 there were as many in the upper, we must conclude that there were 

 at least sixteen in all. 



But as in the case of the elephant, these teeth are never altogether 

 in the mouth. Their succession is regulated as in the case of the 

 elephant, from front to rear. When the back tooth begins to pierce 

 the gum, that in front is worn out and ready to fall ; thus they replace 

 each other in succession. It does not appear that there could have 

 been more than two at each side in full exercise at the same time ; 

 finally, as is the case with the elephant, there is but one. In 

 the lower jaw of plate 22, figs. 1 and 2, where the teeth with ten 

 denticuli is already somewhat worn, we can only discern in front the 

 remains of an alveolus more than half filled. 



But again, we may observe a tooth of six denticuli, and another of 

 eight in the skull represented in plate 20, a tooth of six denticuli, and 

 one of ten in the lower jaw of plate 21, figs. 1 and 2. 



Thus the effective number of teeth which can act together, is eight 

 in the young and only four in the aged animal. 



This result must diminish in a very considerable degree the ideas 

 entertained with respect to the size of the mastodon, by those who 

 supposed that the number of its jaw-teeth equalled that of ours, 

 and who believed that they were all equal to the largest in size. 

 BufFon for instance says — " The square form of these enormous jaw- 

 teeth proves that there were a number of them in the jaws of the 

 animal; and supposing we should allow it but six or four on each 

 side, we may judge of the enormous size of a head which could 

 contain at least sixteen jaw-teeth, weighing from ten to twelve 

 pounds each. (Epochs of Nature, Justificatory Notes, No. 9). 



It was by this reasoning that he was led to attribute to this 

 animal a superiority in size over our largest elephants, although we 

 shall see that there is as yet no proof extant that its height ever 

 exceeded twelve feet, and that, according to BufFon's own account, 

 the Indian elephants sometimes reach fifteen or sixteen feet in 

 height. 



I shall now proceed to examine more in detail these teeth and 

 their variations. 



In plate 19, we may observe four of different sorts and different 

 states, represented at half their natural size. 



Let us begin with those of six denticuli. Fig, 5 is one of those 

 of six denticuli half worn down : it has been copied from a drawing 

 kindly communicated to me by M. Blumenbach, 



The M useum has long been in possession of three similar to these, 

 contributed at a very early period by Fabri, They are the same that 

 Daubenton (Xatural History, xii. No. 1106, 1007, 1108), and BufFon 

 (Epochs of Nature, plate 5) , have taken for the teeth of a gigantic 

 hippopotamus, whereas the hippopotamus has never more than four 

 trefoil figures ; in no case has he six. 



