586 MANUAL OF ZOOLOGY. 



separate compartments, and the caecum is comparatively small 

 and simple. 



The section Artiodactyla comprises the Hippopotamus, the 

 Pigs, and the whole group of the Ruminants, including Oxen, 

 Sheep, Goats, Antelopes, Camels, Llamas, Giraffes, Deer, &c. 

 Besides these there is an extensive series of fossil forms com- 

 mencing in the Eocene or Lower Tertiary period, and in many 

 respects filling up the gaps between the living forms. 



OMNIVORA. 



i. Hippopotamidcz. 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 



2 2 



canines extremely large, , and the molars, T- ?. or - 



i i 77 66, 



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 familiar living form, the Hippopotamus 

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

 continent. It is an enormously bulky and unwieldy animal, 

 reaching a length of eleven or twelve feet. It is nocturnal in 

 its habits, living upon grass and small shrubs, and it swims and 

 dives with great facility. It is found in tolerable abundance in 

 the rivers of Abyssinia, and occurs plentifully in South Africa. 

 A much smaller form (the so-called Hippopotamus or Chce- 

 ropsis Liberiensis) occurs on the west coast of Africa, but it 

 is exceedingly rare, and comparatively little is known about it. 

 It possesses, however, only two lower incisors instead of four. 



2. Suida. The group of the Suida, comprising the Pigs, 

 Hogs, and Peccaries, is very closely allied to the preceding ; 

 but the feet have only two functional toes, the other two toes 

 being much shorter, and hardly touching the ground. All the 

 three kinds of teeth are present, but they vary a good deal. 

 The canines always are very large, and in the males they usu- 

 ally constitute formidable tusks projecting from the sides of 

 the mouth. The incisors are variable, but the lower ones are 



