UNGULATA. 429 



The group of the Artiodactyle Ungulates may be divided 

 into two sections termed respectively Omnivora and Rumi- 

 nant ia, according as they live upon a miscellaneous (but chiefly 

 vegetable) diet, or are exclusively vegetable-feeders and chew 

 the cud. In the former are the living families of the Hippo- 

 potamidce and Suida (Swine), with the extinct group of the 

 Anoploiherida. In the latter are the Camelidcz, Moschidiz 

 (Musk-deer), Cervida (Deer), Camelopardalida (Giraffes), and 

 Cavicornia (Antelopes, Sheep, Goats, and Oxen). 



OMNIVORA. 



i. Hippopotamidce, This group contains only the single 

 genus Hippopotamus, characterised by the massive heavy body, 

 the short blunt muzzle, the large head, and the presence of 



teeth of three kinds in both jaws. The incisors are > the 



canines extremely large, - ?, and the molars, 'L or - - 

 i i y 7 o o 



with crowns adapted for grinding vegetable substances. The 

 upper canines are short, but the lower canines are in the form 

 of enormous tusks, with a chisel-shaped edge. The feet are 

 massive, and are terminated by four hoofed toes each. The 

 eyes and ears are small, and the skin is extremely thick, and 

 is furnished with few hairs. The tail is very short. 



Several extinct species of Hippopotamus are known, but 

 there is only one well-established living form, the Hippopo- 

 tamus amphibius or River-horse, and this is confined to the 

 African continent. 



The genus Hippopotamus may be divided into two sub- 

 genera, in accordance with the number 

 of the incisor teeth. In the sub-genus 

 Tetraprotodon, comprising the living 

 species and most of the fossil forms, 

 there are four incisors in each jaw. In 

 the sub-genus Hexaprotodon, compris- 

 ing several Miocene species from 

 India, there are six incisors in each 

 jaw. 



The best -known fossil species of 



Hippopotamus in Europe is the H. Fig. 353 .-Moiar tooth of H 



$%%. 



ip- 

 major, which is found both in Pliocene * t 



and in Post-Tertiary deposits. This 



species is very nearly allied to the living H. amphibius; but it 



extended its range over the whole of the south of Europe. 



