Memoir upon living and fossil Elephants . 36 J 



are completely untoiiched, and present the summits of their 

 notches in the shape of nipples. 



The anterior lauiinte are also completely destroyed !)efore 

 the posterior ones are strongly cut in front ; and fron) this 

 there follows another pheenomenon, also peculiar to ele- 

 phants ; their teeth diminish in lengtli at the same time 

 that thev diminish in height. 



While the exterior part of the tooth is wearing down and 

 diminishing, the portion of the root which corresponds to it 

 13 worn in another manner, which is more difficult to con- 

 ceive. On examining what remains of it,' we find it as it 

 were pared down ; it presents at its surface small irregular 

 cavities, as if it had been dissolved by an acid thrown upon 

 it drop by drop. It is a kind of caries similar to that under- 

 gone by the human teeth when stripped of their enamel. 

 We shall investigate the cause of this presently. It always 

 happens that the tooth is by this means successively de- 

 prived, in the various portions of its length, of segments or 

 trenches which occupy the v.hole height of it. 



Thence also results another singular efiect : the anterior 

 part of the jaw being always to be filled up, the tooth moves 

 from behind to the front horizontally, while it moves verti- 

 cally from top to bottom, or vice versa, according as it be- 

 longs to the upper or lower jaw. 



This is the reason why every tooth, at the time of its fall- 

 ing, is very small, however large it may have been pre- 

 viously. 



This movement of the tooth makes room for that which 

 is formed in the back jaw, and which must succeed it; this 

 second tooth assists by its development in pushing the first 

 forward ; and we may say that the large teeth of the elephant 

 come behind its young teeth, in place of coming •above or 

 under, as in other animals. 



Patrick Blair*, who had seen separate transverse laminae 

 in the back jaws of the elephant, and who had named theni 

 very justly mdimenls of teeth, was unwilling to believe that 

 these laminie afterwards proceeded to form a tooth which 



• Phil. Trans, vol. xxvii. no. 32C. p. 110'. 



would 



