A Camelidae (Tylopoda). The Camels and Llamas constitute in many respects an aberrant group of the Ruminantia, especially as regards their dentition and the conformation of the feet. The upper jaw (fig. 407) carries three teeth on each side in front, separated by slight intervals. The most anterior of these is a conical incisor; the central one is a canine, and the hindmost is the first praemolar, which is separated by a wide gap from the rest of the molar series, and is pointed in form. In the lower jaw there is also a canine, placed a little behind the incisors, and a detached laniariform praemolar (the latter sometimes absent). In the Llamas these isolated prae-moars do not exist. Each foot terminates in two toes, which are provided with imperfect nail-like hoofs, covering no more than the upper surface of each toe. The two hinder toes, which are mostly present in the Ruminants, are here altogether wanting, and the animal walks upon the hinder surfaces of the toes, which are directed downwards, and are protected by pads of callous horny integument. The stomach is complex, but the manyplies is wanting. As regards their further characters, the head of all the Camelidae is destitute of horns in both sexes ; the nostrils can be closed at the will of the animal; the upper lip is hairy and partially cleft; and the red blood-corpuscles are oval.

Fig. 407.   Side view of skull of Camelus Bactrianus : i Upper incisor; c c Canines ; pm Isolated praemolar. (After Giebel.)

Fig. 407. - Side-view of skull of Camelus Bactrianus : i Upper incisor; c c Canines ; pm Isolated praemolar. (After Giebel.)

The family of the Camelidae is represented in the Old World by the Camels (Came/us), and in South America by the Llamas and Alpacas (Auchenia). There is also an extensive series of Tertiary forms, one of which (viz., Protolabis) is specially interesting as possessing the full number of upper incisors, namely, three on each side of the jaw.

The true Camels are peculiar to Asia and Africa, and two species are known, distinguished from one another by the possession of a double or single adipose hump on the back. The African or Arabian Camel (Camelus Dromedarius) is often called the Dromedary, and has only one hump on its back. The two toes are united together by the callous sole ; and the chest, shoulders, and knees are furnished with callous pads, upon which they rest when they lie down. The hump is almost entirely composed of fat, and appears to act as a kind of reserve supply of food, as it is noticed to diminish much in size upon long journeys. The Camel can likewise support a very prolonged privation of water, as the paunch is furnished with large cells, which the animal fills when it has access to water, and then makes use of subsequently as occasion may require. The structure of the Camel adapts it admirably for locomotion in the sandy deserts of Arabia and Africa ; and as it is very docile and good-tempered, it is almost exclusively employed as a beast of burden in the countries in which it occurs.

The Bactrian Camel (C. Bactrianus) is distinguished by the possession of two humps ; but in other respects it does not differ from the Dromedary. It is found in Turkestan, Persia, Mongolia, and Thibet. The two species are said to breed together, and the hybrid offspring is stated to be occasionally fertile. The place of the Camels is taken in the New World by the Llama and Alpaca, with two other nearly-allied forms. These animals form the genus Auchenia, and are in many respects similar to the true Camels. They are distinguished, however, by having no hump upon the back, and by the fact that the two toes are not conjoined and supported by a callous pad, as in the Camels, but are separate, with separate pads, and w:th strong curved nails. The neck is long and the head comparatively small, whilst the upper lip is mobile and deeply cleft vertically. The Llamas are chiefly found in Peru and Chili. They live in flocks in mountainous regions, and are much smaller than the Camels in size. The true Llami is kept as a domesticated animal, and used as a beast of burden, its wild form being known as the "Guanaco." The Alpaca is still smaller than the Llama, and is not very unlike a sheep, having a long woolly coat. It is partially domesticated, and the wool is largely imported into Europe. Its wild form is the so-called "Vicuna."