TEETH OF UNGULATA. 



361 



290 



apex to that part which was formed when the matrix and the 

 socket had reached their full size. 



These incisive teeth of the elephant not only surpass other 

 teeth in size, as belonging to a quadruped so enormous, but they 

 are the largest of all teeth in proportion to the size of the body ; 

 representing in a natural state those monstrous incisors of the 

 rodents, which are the result of accidental suppression of the 

 wearing force of the opposite teeth, fig. 239. 



The tusks of the elephant, like those of the mastodon, consist 

 chiefly of that modification of dentine which is called * ivory,' 

 and which shows, on transverse fractures or sections, striae pro- 

 ceeding in the arc of a circle from the centre to the circumference 

 in opposite directions, and forming by their decussations curvili- 

 near lozenges. This character is peculiar to the tusks of the 

 Proboscidian Pachyderms. 



In the Indian Elephant the tusks are always short and straight 

 in the female, and less deeply implanted than in the male : she 

 thus retaining, as usual, more of the characters of the immature 

 state. In the male they have been known to acquire a length of 

 nine feet, with a basal diameter of eight inches, and to weigh one 

 hundred and fifty pounds : but these 

 dimensions are rare in the Asiatic 

 species. 



The elephant of Africa, at least 

 in certain localities, has large tusks 

 in both sexes ; and the ivory is most 

 esteemed by the manufacturer for 

 its density and whiteness. 



The molar teeth of the elephant are 

 remarkable for their great size, and 

 extreme complexity of their struc- 

 ture, fig. 290. The crown, of which 

 a great proportion is buried in the 

 socket, and very little more than the 

 grinding surface appears above the 

 gum, is deeply divided into a number 

 of transverse perpendicular plates, 

 consisting each of a body of den- 

 tine, d, coated by a layer of enamel 

 ib., e, and this again by the cement, ib., c, which fills the interspaces 

 of the enamelled plates, and here more especially merits its name, 

 since it binds together the several divisions of the crown before 

 they are fully formed and united by the confluence of their bases 



Section of molar, Elephant. 



