ORDERS OF MAMMALIA. 325 
and have usually four toes to each foot, though sometimes the 
hind-feet have only three toes. All the toes are hoofed, but it 
is only two which support the weight of the body, the remain- 
ing toe or toes being placed at some elevation on the back of 
the foot. The snout is truncated and cylindrical, and is capable 
of extensive movement. The tail is very short, or is represented 
only by a tubercle. 
Of the Swine the most important and best known is the Wild 
Boar (.Szs scrofa), from which it is probable that all our domes- 
tic varieties of swine have sprung. Another form is the Baby- 
roussa or Hog-deer (Sus dabyrussa), which inhabits the Indian 
Archipelago, and is remarkable for the great size and backward 
curvature of the upper canine teeth. The Wart-hogs (Phaco- 
cherus) are African, and derive their name from the possession 
of a fleshy wart under each eye. The Peccaries are exclusively 
American, the best-known species being the Collared Peccary 
(Dicotyles torguatus). They are not at all unlike small pigs 
both in appearance and habits, and they are generally found in 
small flocks. 
The Rumnantia form a most natural group of the Ungulaza, 
characterised by the structure of the foot, the dentition, and 
the structure of the stomach. 
The foot is “ cloven,” consisting of a symmetrical pair of toes, 
encased in hoofs, and looking as if produced by the cleavage of 
a single hoof. In most cases there are also two small supple- 
mentary hoofed toes placed on the back of the foot. 
As regards the dentition, the typical state of things is that 
there should be no incisor or canine teeth in the upper jaw, but 
that the lower jaw should have six incisors and two canines, 
which are all similar in size and form, and constitute a con- 
tinuous and uninterrupted series of ezgh¢ teeth placed in the 
front of the lower jaw. There are six molar teeth on each side 
of each jaw, and these have grinding surfaces. The typical 
dental formula, therefore, for a Ruminant is— 
z re ; c2-°; pm and m nee m9: 
In the absence of incisor teeth in the upper jaw, the lower in- 
cisors bite against a callous pad of hardened gum. ‘The Camel 
tribe differs in its dentition from the above typical formula, and 
certain exceptions likewise occur in the males of some other 
forms, and in one or two other less important instances. 
