# Natural History: Mammalia/Pachydermata

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ORDER VI. PACHYDERMATA.
(Thick-skinned Animals.)
This Order contains animals, which, while they have certain features in common, warranting their association, present so much diversity in detail, as to lack the apparent unity and completeness which other similar groups possess. By the aid, however, of fossil genera and species, unknown in a living state, many blanks are filled up, and links are supplied, by which the creatures of this Order are arranged in a more regular and complete series. In no other Order of Mammalia have the discoveries of organic remains been so copious and so important as in the present.
The Pachydermata are, for the most part, animals of large size, and many are of gigantic proportions. They are generally also uncouth and clumsy in form, and heavy in their motions. The name, which Cuvier selected to distinguish the Order, describes a peculiarity, most obvious in the great tropical genera, but more or less observed in all, the thickness of their skin. In the Whales we saw the skin greatly thickened, in order to hold in its tissues the blubber or surface-fat: in some of the Pachydermata, as the Hogs and Hippopotamus, there is, in like manner, a tendency to the deposition of a thick layer of fat on the surface of the body, but it is beneath, and not within, the integuments. The skin is usually dense and leathery in its consistence; its external appear​ance is frequently rough and coarse, thinly clothed with bristly hairs, or almost entirely naked.
The food of these animals is exclusively vegetable: various grasses and aquatic herbage; the thick and succulent plants of tropical plains; bulbous and farinaceous roots; and the young twigs of trees, afford them variety of nutrition. The stomach, however, is either simple, or, where compound, is not capable of the process of rumination. The molar teeth are compound, often triple, with flattened crowns: in many, there is a peculiar development of the canines or incisors into curved and projecting tusks. The muzzle is frequently produced into a projecting proboscis, as in the Elephants, Tapirs, and in a less degree in the Hogs; or into a lengthened and flexible upper lip, as in most of the Rhinoceri.
Being destitute of clavicles, the fore limbs of the terrestrial Pachydermata have not the freedom and mobility necessary to constitute them organs of climbing, or of seizing and holding prey, or of dealing and warding blows in conflict. The limbs are simply organs of motion, and of support; hence they assume the form of pillars, more or less perpendicular; and their extremities, though divided as to the skeleton into distinct toes, are so encased in the common integuments as to be undivided externally, except that the last joints of the toes are encased in hollow, box-like hoofs. In the first family, the link which connects the present Order with the preceding, the hind limbs are wanting, and the fore limbs resemble the swimming paws of the Whales; the extremities of the toes, however, being marked by small horny claws.
The torrid zone, and those regions which are ​contiguous to the tropics, are the home of the Pachydermata, and they most abound in the hottest parts of Africa, and of continental and insular Asia. The Hog, the Horse, and the Ass, are dispersed in a state of domestication, wherever civilized man has taken up his abode. The largest of all terrestrial animals are found in this Order; and they exhibit a massiveness of form and structure, combined with a strength that is almost irresistible. "Their pace, when they have fairly commenced it, from the length of their stride, and the great propelling weight of their bodies, is for a time very rapid, and bears before it all ordinary obstacles, clearing a way through the thickest and most matted underwood." For the most part, they are peaceful and inoffensive, but, if irritated, they frequently manifest a furious and vindictive ferocity. Some of the African Rhinoceri are, however, of a spontaneously savage and spiteful disposition.
The Pachydermata present some difficulty in their subdivision, but we may consider them as comprised in five families, Manatidæ, Elephantedæ, Suidæ, Rhinocerotidæ, and Equidæ.