FAMILY ELEPHANT1D.E J MASTODON. 323 



water deposits of the newest tertiary series. They are com- 

 monly associated with remains of other animals ; of which some 

 may be referred to existing genera ; whilst many (some of which 

 will be hereafter noticed) present forms, of which we have not 

 any representatives amongst the races now living. 



289. Nearly allied to the Elephants is an extinct genus, 

 termed the Mastodon^ which was characterised by the form of its 

 molar teeth. These, instead of having the enamel disposed in 

 ridges, had their crowns raised up into conical eminences, with 

 deep furrows between them ; and these were worn down by 

 friction, into disks of various sizes, very much as in the Pig, 

 Hippopotamus, and other Pachydermata. In the young state, 

 moreover, there were small tusks projecting downwards, in the 

 lower jaw (as well as in the upper) of both sexes ; but both of 

 these disappear in the adult female, and only one remains in the 

 male. From the examination of a young specimen possessing 

 these tusks, it was at first supposed that it belonged to a distinct 

 genus, to which the name of Tetracaulodon (or four-tusked) was 

 given. The Mastodon giyanteus, of which a very fine skeleton 

 was recently (1842) exhibited in London, under the name of the 

 Missouri Leviathan, must have considerably exceeded in size 

 the largest Elephants of the present day. Its remains are con- 

 fined to the American continent, and are very abundant in some 

 parts, especially in the saline morass popularly termed the Big 

 Bone Lick. Several other species of Mastodon, however, have 

 been distinguished by their remains ; of these some were natives 

 of the Old World, and probably even of Britain ; but they were 

 for the most part considerably smaller than the gigantic Mastodon 

 of North America. 



290. On the principles which should regulate the subdivision 

 of the group of ORDINARY PACHYDERMATA into families, Natu- 

 ralists are not yet agreed ; the number of dissimilar forms which 

 it contains being so great, as to render their arrangement very 

 perplexing. The division which will be here adopted is founded 

 upon that of Cuvier; but may not improbably require future 

 modification. In the first family of this group, including the 

 Rhinoceros, Tapir, Hyrax, and several extinct genera, the feet do 



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