Pachydermata
From BiblePortal Wikipedia
Webster's Dictionary [1]
(n. pl.) A group of hoofed mammals distinguished for the thickness of their skins, including the elephant, hippopotamus, rhinoceros, tapir, horse, and hog. It is now considered an artificial group.
The Nuttall Encyclopedia [2]
Hoofed animals with thick skins and non-ruminant, such as the elephant and the hog.