ODONTOGRAPHY. 57 



laminse only being visible, lies the fifth tooth : in consequence of its iafli 



Tooth. 



situation, it cannot be exactly measured. The corresponding tooth in the 

 upper jaw measures seven inches in length, and contains fourteen plates; 

 three of which, the posterior, are not cemented to the body of the tooth ; 

 and, no doubt, others would have been added as the tooth came into place. 

 This tooth is peculiarly situated. The upper jaw not having sufficient space 

 to accommodate it behind the working tooth, it is placed obliquely between 

 a horizontal and a vertical line, and may be said to extend from below 

 upwards, rather than from before backwards. When the working tooth is 

 worn away, this comes into its place by a circular or curvilinear movement, 

 and, from a perpendicular tooth, becomes horizontal. This is the mode in 

 which the posterior molars are developed. The plate of bone investing the 

 posterior and lateral parts of this undeveloped tooth, which is the ptery- 

 goid process, is very thin, and may be readily broken away. 



This succession of teeth is given altogether from specimens of the 

 Asiatic Elephant. 



In the collection of the Boston Society of Natural History, there is a Elephant of 



Nat. Hist. 



very perfect skeleton of a young Asiatic Elephant, which died during its society. 

 passage to this country, and was dissected here. The age of this animal, 

 from its size and the state of its epiphyses, was supposed to be about ten 

 years. Comparing it with a young living elephant, five years old, lately 

 exhibited in Boston, this skeleton might have a somewhat greater age than 

 was attributed to it. The appearances of the teeth in the head of this 

 skeleton are as follows : One tooth in its place, on each side of the lower 

 jaw, contains ten ridges, and measures six inches and a half antero-poste- 

 riorly, by three transversely. An undeveloped tooth, mostly imbedded in 

 the bone, is situated behind the preceding. In the upper jaw, on each 



8 



