186 



ORDERS OF MAMMALIA. 



accordance with this, Dr Falconer divided the Mastodons 

 into two principal sections, which he named respectively 

 Trilophodon and Tetralopliodon. In the first of these are 

 such forms as M. giyantcus (fig. 668, b) of the Post-Pliocene, 



Fig. 06S.— A, Skull of Mastodon giganteus (= M. Qhioiicus) ; b, SiJe view of tlie secoiiil 

 true molar of the same. (Mter Owen.) 



31. tapiroides and M. aiKjustidcns of the Aliocene, &c., in 

 which there are three ridges to the molars. In the second 

 group, on the other hand, are such forms as the Miocene M. 

 longirostris and M. latideiis, and the Pliocene M. Arverncnsis 



Fig. I309.- — Profile view of the last upper molar of Mastodon Siraknsis, one-third of the 

 natural size. From the Upper Miocene of India. (After Falconer.) 



(Hg. 670), in which the molars are four-ridged. Lastly, in 

 M. Sivalensis (fig. 669) we liave a form in which the molars 



