5l6 MANUAL OF ZOOLOGY. 



fourth (fig. 197, B, C). The dorso-lumbar vertebrae are nineteen 

 in number, and there is no third trochanter on the femur. If 

 true horns are present, these are always in pairs, and are sup- 

 ported by a bony horn-core. The antlers of the Deer are also 

 paired, but they are not to be regarded as true horns. The 

 stomach is always more or less complex, or is divided into se- 

 parate 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. 



1. HippopotamidcR. 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 



2~~^2 



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



2 2 



canines extremely large, - , and the molars ^ or ? -^ 



with crowns adapted for grinding vegetable substances. 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 Hippopotamus am- 

 phibius, 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. Another 

 supposed species (H. Liberiensis) occurs on the west coast 

 of Africa, but there is some doubt as to the specific distinct- 

 ness of this. 



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 placed at some elevation above the ground, and being 

 rudimentary. All the three kinds of teeth are present, but they 

 vary a good deal. The canines always are very large, and in 



