The name _Tylopoda_, by which the Camels, together with the Llamas, are known to naturalists, is derived from two Greek words (τύλος, a knot or callus, and πούς, a foot), signifying that the feet, instead of being protected by hoofs, are covered with a hardened skin, enclosing the cushion-like soles of the feet, which are so constructed that they spread out laterally when brought in contact with the ground, an arrangement of evident advantage to desert-ranging animals. The tips of each of the two toes are protected by nails, as can be seen in the accompanying drawing. [Illustration: FOOT OF CAMEL.] There are also other points in which these creatures differ from the more ordinary Ruminantia. In the front of the upper jaw there are two teeth--one on each side, placed laterally--which correspond to the side cutting teeth in man, and to the similarly-situated “nippers” of the Horse. In the Deer, Ox, Sheep, and their allies there is not a trace of these, as has been previously explained (page 4). As to the limbs, it may also be mentioned that the true knee-joints--which in animals like the Horse are almost entirely hidden within the general skin-covering of the body--are much more conspicuous and free. The stomach is peculiar; it wants the “manyplies,” or third compartment, but possesses the “paunch,” “honeycomb-bag,” and “abomasum,” the last-named of which is of great length. In the walls of the paunch there are present two extensive collections of “water-cells,” which serve their owners in good stead whilst traversing the desert or residing in regions where fresh water is not to be procured except with difficulty. [Illustration: Fig. A.--STOMACH OF THE LLAMA.] [Illustration: Fig. B.--WATER CELLS OF THE CAMEL’S STOMACH.]