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.