Pachydermata — Thick-Skinned Quadrupeds
All the animals of this great order are classified under the name Pachydermata, which is derived from two Greek words meaning thick-skinned. In nearly all of them the toes are rendered motionless by a horny covering which surrounds them, called a hoof, which blunts them to the sense of touch; and the form of this hoof helps to divide the order into families. There are three divisions in the Pachydermata—the Elephant family, known as the Proboscidae (from the Latin word proboscis, meaning a trunk); the family of ordinary Pachydermata, including the Hippopotamus, Rhinoceros, Hyrax, Tapir, Wild Boar, Phacocheres and Peccari; and the family of Solipedes, the name of which is derived from the Latin words solus, alone, and pes, pedis, a foot, and includes the animals with undivided hoofs, like the Horse, the Donkey, Hemionus, Daw, Zebra and Quagga.