576 CHORDATA. 
as there are no upper incisors. There is, however, a pair of well- 
developed upper canines. The molars are selenodont. The stomach 
is complex, Jacking only the manyplies of the Pecora. The ecto- 
cuneiform, navicular and cuboid bones fuse in one, and in most the 
third and fourth metapodials fuse together. The chevrotains resemble 
the Swzde in having a diffuse placenta and in the presence of a complete 
fibula, whilst in one genus, Dorcatherium, the third and fourth meta- 
podials are not fused. The chevrotains ( 7ragzlus) are found in the 
forests of the Oriental Region and the water-chevrotain ( Dorcatherium ) 
is found in West Africa. 
They are an interesting family, showing anatomical characters partly 
resembling the Swzde and partly the Pecora. In the complete fusion 
of distal tarsal bones they go beyond both these families. Dovcathertum 
is found in the Miocene and Pliocene of Europe and India. 
Family IV.—Camelidz.—The camels form with the American 
llamas and their allies a natural family. They have three pairs of 
upper incisor teeth in the young, but all except the third incisor are lost 
later. Canines are present and the molars are typically selenodont. 
The loss of the two pairs of upper incisors foreshadows the condition 
found in the Pecora. The stomach has only two compartments 
corresponding to the first and fourth of the Pecora. The tarsal and 
carpal bones are distinct and separate, but the third and fourth meta- 
podials are fused to form a ‘‘cannon bone.” The third and fourth 
toes are alone present and the weight is borne upon pads under 
the penultimate phalanges; the small nail-like hoofs do not touch 
the ground. The placenta is diffuse. The camels are indigenous to 
Western and Central Asia. In South America are found the closely 
allied and similarly domesticated Hama (Auchenia) and the alpaca, 
with their wild relatives, the guanaco and vicufia. They inhabit 
mountainous regions and are domesticated for their wool. 
Family V.—Pecora.—The ecora are the most important family of 
Ungulata, comprising deer, antelopes, sheep, oxen and the giraffe. 
They have the following characters in common, with isolated exceptions. 
The upper incisors and canines are lost and replaced byahard pad. The 
molar teeth are selenodont and show every gradation from brachydont 
to hypsodont types. The stomach is complex, with four compartments 
(see Ox, page 514). The cuboid and navicular bones are fused and the 
third and fourth metapodials are fused to form the ‘‘ cannon bone.” 
There are usually only traces of the second and fifth toes. The fibula 
is completely fused to the tibia and the ulna to the radius. Most early 
fossil Pecora and a few modern types (musk-deer) have no processes of 
any kind on the head, but the majority of modern forms have paired 
tony processes attached to the frontal bones. These may be small and 
permanently covered with hair, as in the giraffe, or they may when 
complete consist of naked bone and are then known as antlers, as in 
deer: these antlers are shed annually. Lastly, the bony core may 
form a central support for a hollow ‘‘ horn” of epidermic structure. The 
horn is never (except in the American Prongbuck) shed and grows 
perpetually from the base. The young deer has no frontal processes, 
