HYEACOIDEA AND PROBOSCIDEA. 387 



are live-ridged, tlie last being six-ridged ; aud for this type 

 Dr Falconer proposed the name of Pentalojjhodon. 



Fig. 070. — Third milk-molar of the left side of the upper jaw oi Mastodon Arveriiensis, 

 sliowing the grinding surface. Pliocene, (After Lyell.) 



The distribution of the genus Mastodon in time is some- 

 what peculiar, since it commenced both in Europe and Asia 

 in the Miocene, and died out in the Pliocene ; whereas in 

 America it does not seem to have made its appearance till 

 the Pliocene, and it survived throughout the whole of the 

 Post-Pliocene period. It is clear, then, that Mastodon, like 

 EU'plias, originated within the Old World, and reached the 

 Xew World by migration at a later date. Both the Trilo- 

 phodont and Tetralophodont types of the genus appear to 

 have been represented in the Miocene period, the former 

 being represented by the M. tcqnroides and M. angustidons 

 of the Upper Miocene of Europe, and the latter by the M. 

 longirostris of Europe, and the 31. latidens and M. Ferimen- 

 sis of India; while the Pentalophodont type is represented 

 in the Upper Miocene (Siwalik formation) of India by M. 

 Sivalensis. In the Pliocene of Europe the best known forms 

 are the M. {Tdralo'phodon) Arvernensis of Britain and the con- 

 tinent of Europe, the M. Andium of South America, and 

 the M. {Tetralophodon) mirificus of JSTorth America. In the 

 European and Asiatic areas, as before remarked, no members 

 of the genus Mastodon have hitherto been detected in de- 

 posits newer than the Pliocene ; but in North America the 

 great Mastodon giganteus or M. Ohioticus abounded in the 



