ELEPHANTS. 69 



the different species or races according to sex, nearly as do the horn. 

 of ruminants. In India and Malacca, the males alone are provided 

 with well-developed tusks. The elephant of Ceylon," adds Mr. 

 Darwin, " is considered by most naturalists as a distinct race ; there, 

 ' not one in a hundred is found with tusks, the few that possess them 

 being exclusively males.' The African elephant is undoubtedly dis- 

 tinct, and the female has large well-developed tusks, though not so 

 large as those of the male." The molars or grinding teeth exhibit an 

 equally curious structure. In the lifetime of an elephant twenty-foui 

 molar teeth are developed in all ; six on each side of each jaw. But 

 at any one time in the life of the animal, not more than two of these 

 teeth are to be seen in each side of the jaw. A curious succession 

 of these molars takes place in the elephants ; for they are found to 

 move from behind forwards ; the teeth in use being gradually ousted 

 from their place by their successors, as the former are worn away 

 Thus the whole set of molars in due time moves forwards in the jaw, 

 and each successive tooth is, as a rule, larger than its predecessor. 

 In structure, the molars of the elephant are highly peculiar, each 

 exhibiting the appearance rather of a compound than of a single 

 tooth. Each tooth is built up of a series of plates set perpendicu- 

 larly in the tooth, and consisting of ivory or ' dentine " covered by 

 enamel, whilst " cement " fills up the interspaces between the plates. 

 As the tooth wears in its work, the enamel comes to project above 

 the surface of the tooth, and a characteristic pattern is thus developed 

 on the surface of the molars of each species of living elephant. 

 Thus, in the Indian elephant, the molars exhibit a series of cross 

 ridges, which are more numerous than those of the African species ; 

 whilst in the latter form, the enamel plates form a distinctly lozenge- 

 shaped pattern. It sometimes happens that in elephants kept in 

 captivity the succession of the teeth is disarranged, from the fact 

 that the molars are not worn away fast enough, and the succeeding 

 teeth are displaced, thereby causing deformity of the jaws. 



The elephants were included in the older systems of classification 

 in a somewhat heterogeneous group of quadrupeds named the Pachy- 

 dermata. That this order now abolished and divided to form several 

 new groups was motley enough in its representation, is readily seen, 

 when we discover that the rhinoceroses, hippopotami, and other forms 

 were included within its limits along with the elephants themselves. 

 The technical name "Pachydermata" related to the thick skin which 

 invests the bodies of the animals just mentioned, and in the elephants 

 this characteristic is, of course, extremely well represented. The 

 thick skin hangs in folds on the body, whilst the typical hair-covering 

 which by natural right all quadrupeds possess is but sparsely developed. 

 It would seem, however, that the young elephant possesses a much 

 more profuse covering of hairs than the adult. Such a statement is 



