^76 CHORD ATA. 



as there are no upper incisors. There is, however, a pair of well- 

 developed upper canines. The molars are selenodont. The stomach 

 is complex, lacking only the manyplies of the Pecora. The ecto- 

 cuneiform, navicular and cuboid bones, fuse in one, and in most the 

 third and fourih metapodials fuse together. The chevrotains resemble 

 the SiiidcE in having a diffuse placenta and in the presence of a complete 

 fibula, whilst in one genus, Dorcatheriu/?i, the third and fourth meta- 

 podials are not fused. The chevrotains ( Tragtilus) 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 SiddcB and partly the Pecora. In the complete fusion 

 of distal tarsal bones they go beyond both these families. Dorcatherium 

 is found in the Miocene and Pliocene of Europe and India. 



Family IV.^Camelidae. — 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 Peco7^a. 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 llama ( Aticheiiia) and the alpaca, 

 with their wild relatives, the guanaco and vicuna. They inhabit 

 mountainous regions and are domesticated for their wool. 



Family V. — Pecora. — T\iQ. Pecora 2.x^ 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 by a hard 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 

 bony 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, 



