360 



ANATOMY OF VERTEBRATES. 



and destruction, of shedding and replacement : and all the grinders 

 succeed one another, like true molars, horizontally, from behind 

 forwards. 



The total number of teeth developed in the elephant appears 



O Q df* 



to be i ' ,ra fi = 28 : the two large permanent tusks being 



preceded by two small deciduous ones, and the number of molar 



teeth which follow one another 



on each side of both jaws being 289 



not less than six, of which the 



last three answer to the true 



molars of other mammals. 



The deciduous tusk appears 

 beyond the gum between the 

 fifth and seventh month ; it 

 rarely exceeds two inches in 

 length, and is shed between 

 the first and second year. 



The permanent tusks cut 

 the gum when about an inch 

 in length, a month or 



usually after the milk-tusks 

 are shed. Their widely open 

 base is fixed upon a conical 

 pulp, which, with the capsule 

 surrounding the base of the 

 tusk and the socket, conti- 

 nues to increase in size and 

 depth, obliterating all vestiges 

 of that of the deciduous tusk, 

 and finally extending its base 



Section of cranium and tusk of Elephant. 



close to the nasal aperture, fig. 



289, n. The tusk, being subject to 

 no attrition from an opposed tooth, but being worn only by the oc- 

 casional uses to which it is applied, arrives at an extraordinary 

 length, following the curve originally impressed upon it by the 

 form of the socket, and gradually widening from the projecting 



