30 GIJDE TO THE FOSSIL MAMMALS AND IJIKDS 



Fig. 18.— Palatal view of skull (A), symphysis of lower jaw (B), and grindiug 

 surface of molar tooth (C) of an extinct Hippopotamus [Hippopotamus 

 bivalensis), from the Lower Pliocene of the Siwalik Hills, India; A 

 and B one-eighth nat. size, C one-half nat. size. (Pier-case 12.) 



Pier-case 

 13. 



1'lie true pigs, m- Suidse. lia\e always beeu coiitiued to 

 the ( )1(1 AVoild, and tli<' oldest known species is Siis chceruiilcs, 

 t'loni tlie Middle and I pjier ^Miocene of France and Italy. 



.Vmoiig the fossil remains 



<jf tins family in Pier- 



ca'^e 13 may be noticed 



skulls, jaws, and teeth of 



the M'ild ])oar from England 



and Ireland ; some fine 



</ a ~~^^ skulls and jaws of the large 



Fig. I'J.— Grinding surface of third Sus crijmantkius, from the 



right lower true molar tooth of an Lower Pliocene of Pikeruii, 



existing Pig [Sus cristatm), from (-^eece ; pieces of skuUs 



India; nat. size. a, d, middle , • ' ^ ,• i.i i- <- 



columns of talon of tooth. and jaws ot other extinct 



species from the Lower 

 Pliocene of the Siwalik Hills, India ; and similar remains 

 of Hippohyus sivalensis, a pig from the Siwalik Formation 

 Avith deepened grinding teeth rendered very effective by the 

 crimping of their enamel. 



