MAMMALIA. 409 



first tooth wears away, the second tooth is advancing forward ; 

 when the first becomes worn and nseless, the second tooth 

 takes its place, its former position being now occupied by the 

 third tooth, which in course of time is carried forward to the 

 front of the mouth, serves its distinct i)urpose, and when worn 

 down is succeeded by that which was the fourth. 



" There are few examples of natural structures," says Pro- 

 fessor Owen, " that manifest a more striking adaptation of a 

 highly complex and beautiful structure to the exigencies of the 

 animal endowed with it, than the gruKhng teeth of the Ele- 

 phant. Thus the jaw is not encumbered with the whole weight 

 of the massive tooth at once, but it is formed by degrees as it 

 is required ; the sub-division of the crown into a number of 

 successive plates, and of the plates into sub-cylindrical pro- 

 cesses, presenting the conditions most favourable to progressive 

 formation."* Another advantage is pointed out by the same 

 high authority: — "The tooth in front, which is partially worn 

 down, is fitted for the first coai'se grinding of the branches of 

 a tree ; the transverse enamelled ridges of the succeeding 

 part of the tooth divide the food (as it passes on towards the 

 throat) into smaller fragments, and the posterior islands and 

 tubercles of enamel pound it to the pidp fit for deglutition." 



It may readily be supposed that the number and thickness 

 of the plates, the shape of the teeth, and the different patterns 

 in which the enamel is arranged, form characters by which the 

 teeth of the same species in different stages of maturity may be 

 recognized, and that they also fiu-nish the means of separating 

 those of the African from the Asiatic Elephant ; and both of 

 these from that extinct species known as the Mammoth (^EU- 

 phas primigenius) . 



The teeth of the Mammoth, which are thus easily distin- 

 guishable, are found in the superficial unstratified deposits of 

 the continent of Europe ; and with them are associated the 

 remains of two other animals, belonging to the present order, 

 and now found only in wai'mer latitudes— the Hippopotamus 

 and Rhinoceros. 



When such statements were first made by Cuvier, it was no 

 wonder they were received with incredulity; and that even 

 when they were admitted, reference should be made to the 

 Elephants introduced by Pyrrhus in the Roman wars, and to 



* On Britbh Fosail Mammalia. 



