XIII] OF ELEPHANTS' TEETH 903 



elements in the African, and of twice as many (twice as much 

 flattened or compressed) in the Indian elephant; in the mastodon 

 they are much fewer and much larger, and their great tuberculated 

 crowns never wholly wear away. In an old but admirable paper 

 on the Indian elephant*, Mr John Corse says: "The number of 

 teeth of w^hich a grinder is composed varies from four to twenty- 

 three, according as the elephant advances in years; so that a 

 grinder, or case of teeth, in full-grown elephants, is more than 

 sufficient -to fill one side of the mouth.... The same number of 

 laminae generally fills the jaw of a young or of an old elephant; 

 and from three till fifty years there are from ten to twelve teeth or 

 laminae in use, in each side of either jaw, for the mastication of 

 the food." 



The molar teeth of a mouse, a hare or a capybara are Hkewise 

 composite structures; they shew, precisely after the fashion of the 

 elephant, successive narrow annular islands of enamel, with dentine 

 within and cement between, all in varying degrees of independence 

 or coalescence I . 



The molars of a hippopotamus are composite but to a less degree ; 

 his upper molars have each two pair of roots, the last molar one 

 root more. A block of dentine lying transversely to the jaw, with 

 a pair of roots below and a pair of enamel-covered cusps above, is the 

 unit of dentition, and is analogous to the young toothlet of the 

 elephant. 



In the horse and its kind the teeth are long and deeply sunk in 

 the jaw, very much as in a rabbit or hare. Their length is made 

 up not of root but of elongated crown, in which the deep valleys 

 between the once high cusps are filled or flooded with cement; and 

 these long crowns are soon worn down to an all but level surface, 



* J. Corse, Observations on the different species' of Asiatic elephant, and their 

 mode of dentition, Phil. Trans. 1799, pp. 205-236; and cf. Owen's Comp. Anat. 

 m, p. 361. 



t The elephant (in my opinion) shews its likeness or affinity to the rodents 

 throughout its whole anatomy, the metaoromial process of its scapula being one 

 conspicuous indication. Hyrax and Elephas are two isolated forms lying near the 

 common origin of ungulates and rodents; the one lying rather to the ungulate 

 side, the other to the rodent side, of the vague and indefinable border-line. On 

 the relation of the rodent's dentition to the elephant's (a view strongly opposed 

 by Dr \V. K. Gregory), see M. Friant, Contribution a Tetude. . .des dents jugales 

 chez les Mammiferes, Bull. Mus. Hist. Nat. i, pp. 1-132, 1933. 



