66 FAUNA ANTIQUA SIVALENSIS. 



equally wanting in the mastodons and in the true elephants. 

 With respect to the species, while M. de Blainville has judi- 

 ciously rejected a great many of the nominal forms which 

 have been proposed on slender grounds, he appears in other 

 cases to have pushed this numerical reduction too far, and to 

 have mixed up under the same name species which are essen- 

 tially distinct. This remark applies especially to the Indian 

 fossil forms, three or four of which are combined under E. 

 latidens ; and to the European M. angusticlens, which, as 

 defined and illustrated in the ' Osteographie,' includes two 

 sej^arate species. 



Professor Owen has been engaged upon the same subject, 

 contemporaneously with M. de Blainville. In addition to 

 the memoir upon the North American mastodon previously 

 referred to, oui- eminent countryman has discussed the syste- 

 matic relations of Elephas and Mastodon, in his ' British 

 Fossil Mammalia,' and in his very valuable work upon the 

 teeth, lately published. In the latter work he has shown, 

 for the first time, that the molar teeth of the elephants and 

 mastodons, while they agree with each other, form no excep- 

 tion from the normal division into sets presented by the 

 ordinary Pachydermata,' and that the apparent anomaly in 

 the order of their succession arises from the partial or total 

 suppression of the successional series of premolars. In the 

 former work, after describing the differences in the form of 

 the teeth of the two genera, he adds : — 



' A more important difference presents itself when the 

 teeth of the typical species of mastodon are compared with 

 those of the elephants, in reference to their structure. The 

 dentme, or principal substance of the crown of the tooth, 

 is covered by a very thick coat of dense and brittle enamel ; 

 a thin coat of cement is continued from the fangs upon the 

 crown of the tooth, but this third substance does not fill up 

 the interspaces of the division of the crown, as in the ele- 

 phant. Such, at least, is the character of the molar teeth of 

 the first discovered species of mastodon, which Cuvier has 

 termed Mastodon giganteus and M. angustidens. Fossil remains 

 of proboscideans have siibsequently been discovered, princi- 

 pally in the tertiary deposits of Asia, in which the number 

 and depth of the clefts of the crown of the molar teeth, and 

 the thickness of the intervening cement, are so much in- 

 creased as to establish transitional characters between the 

 lamello-tuberculate teeth of elephants and the mammillated 

 molars of the typical mastodons ; showing that the charac- 

 ters deducible from the molar teeth are rather the distin- 



' Supra, p. 51. 



