CAMEL'IDZE (Neo-Lat.. from Gk. KcianXos, kame/os, camel). The camel family, constituting a section of the ruminants termed Tylopoda, in reference to the character of the feet. This family is composed of two genera—et/7110ms, with two species (see CAmEL), and Llama, the ican llamas, considered by some naturalists one species, by others four. (See LLAMA. ) These animals agree in peculiarities of structure. which separate them from other ruminants, mainly as follows: Though a full set of incisor teeth are present in the young, only the outermost tinue through life as iso lated laniariform teeth: canines are present in both jaws, and the mo ]ars are solenodont in type. The skeleton has many peculiarities, of which a striking one is the excessive compara tive length of the thigh bone, and the detachment of the hind leg from the body. The limbs are long, the ankle-bones peculiar, and all traces of pha langes are lost, except the third and fourth. These are not incased in matched hoofs, like other artiodactyls. but the foot consists of two elongated toes, each tipped with a small, nail-like hoof, the feet resting not upon the hoofs, but upon elastic pads or cushions under the toes. In the camels the toes are united by a common sole, thus rest ing upon one extended pad, instead of having each a separate one, as in the llama group, the broader expanse of the foot enabling the ani mals of the one genus more easily to traverse the loose sand of the des ert, while the narrow form and separation of the toes in the other is suited to the uneven surface of rocky heights. The head is long. NVit lima any horns or antlers, the lips extended and mobile, the neck of un usual length; the blood-corpuscles are oval in stead of circular, as in all other mammals, and the digestive organs are characterized by a re markable peculiarity in the struetur9 of the stomach. "Though these animals ruminate." to quote Flower and lydekker, "the . . . in terior of the rumen or paunch (see RUMINANT) has no villi on its surface, and there is no dis tinct psalterium or many plies. Both the first and second compartments are remarkable for the presence of a number of pouches or cells in their walls, with muscular septa. and a sphineter-like arrangement of their orifices, by which they can he shut oil from the rest of the cavity, and into which the fluid portion only of the con tents of the stomach is allowed to enter." Such is the celebrated arrangement by which the camel stores in its stomach more water than it can immediately use, and by gradually using it is able to make far longer journeys across arid regions than otherwise would he possible. This has customarily been regarded as a very strik ing special provision for the needs of the camel of the desert ; but it is equally characteristic of the llamas, which inhabit well-watered re gions. and has evidently descended to both from
a remote common ancestry, regardless of present environments. See ALIMENTARY SYSTEM.
The structural evolution of the camel recalls that of the horse. (See EQuin.+1.) In the old est Tertiary rocks of the ancient lake region of the Rocky Mountains, at the dawn of the Eocene, have been found diminutive remains suggesting this type. and in the Upper Eocene fossil skele undoubtedly cameloid. These belong to an animal (Prototylops) hardly larger than a jack rabbit, yet camel-like in many particulars. It had four distinct toes, of which the third and fourth were most useful, while the lateral sec ond and fifth were smaller; the metapodial hones were disconnected, and thew was no space be tween the ininodont molars and the front teeth, where the eanines and incisors were alike. By changes that went on analogous to those in other ungulates, there is found in subsequent cameloid forms increase in size, and a constant tendency toward acquiring the dentition and pedal anat omy characterizing modern forms. The next advanced firm is greater in size, and the lateral toes. no longer useful, hang to the side of the foot above the ground like a deer's. A steady increa:w of size goes through the ascending for mations of the Nlioeene. until ire reach Pro caniclus. at the top of the Miocene (Loup Fork beds of Wyoming), which was as big as a sheep and very llama-like, with teeth nearly of modern type and the met:ipodial hones firmly united when fully adult. During the Nlioeene the western -American plateau seems to have been an arid desert, and under such conditions were developed the large, splayed feet, bereft of the useless side toes, the great sole-pads, and the laurelled stomach that characterize the race. At the close of the NIMeene, however, there came about a steady ehange toward a waning., moister climate, inducing forest growth, which put au end to camel life in North America. Nleanwhile they had migrated into South Amer ica, where fossil remains of great size are fotind, and where the family still survives, in the nonlified and perhaps degenerate forms of the llamas; and also northwestward to Siberia, and thence into Central Asia, where their remains are found in the Pliocene rocks of India, but not earlier. Here the conditions were favorable, and the modern camels seem to have developed. It thus appears that North America was the original home of the Camelida., and that they "were derived from pig-like animals quite inde pendently of the true ruminants." For particu lars ;IA to American fossil cancels, consult Wort loan, Bulletin Anterieun Museum Natural His to•y, X. (New York, 1893).