THE DOCILE MAMMALS. 251 



a full, rounded forehead and large ears, with four hoofs on 

 the fore feet and three on the hind feet, the Asiatic ele- 

 phant having one more hoof on each foot. 



The Hoofed Mammals. The larger proportion of mam- 

 mals belong to this interesting order, which comprises 

 nearly all those species of mammals useful to man, such as 

 the ox, camel, pig, deer, and horse. They are, in general, 

 characterized by walking on their toes, each toe being at 

 the end encased in a horny hoof ; not more than four toes 

 are completely developed on a foot. The collar-bone is 

 absent. The brain still remains small compared with the 

 bulk of the skull. 



The Ungulates have been divided by Owen into two sub- 

 orders, according to the odd number of toes ( Perissodactyla) 

 or even number (Artiodactyla). In the odd-toed Ungu- 

 lates (Perissodactyles) there may be three toes on each foot, 

 as in the rhinoceros, or one, as in the horse; while in the 

 even-toed Ungulates (Artiodactyles) there may be four 

 toes (Hippopotamus), or two, as in the giraffe, or two func- 

 tional and two rudimental, as in the ox and deer, i.e., most 

 ruminants. 



It will be seen that the character of prime importance 

 in these mammals is the limbs, and particularly the feet. 

 Walking on their hoofs, which are modified claws, they can 

 neither climb, nor dig, rarely using them as weapons of 

 offence or defence. The hoofed beasts are swift on their 

 feet, and perhaps as swift as any is the race-horse, which 

 runs on a single toe in each foot. The horse is among the 

 most specialized of all backboned animals, i.e., its feet are 

 most specially modified, unless we except the limbs of birds. 



The hoofed mammals browse on leaves or grass, and 

 their teeth, both in position and shape, are well adapted for 

 biting and chewing their food. They have no more teeth 

 than they need. In the sheep, deer, and ox, which grasp a 

 bunch of grass with their tongue pressed against the roof 

 of the mouth and then give it a tug, pulling up a mouthful 

 at a time, there is no need of incisors in the upper jaw; 



