156 MAMMALS

which reach the ground, and four behind ; and the
hippopotami, with four toes on the ground both back
and front. In the peccaries the upper canines grow
downwards; in the pigs they grow upwards or out-
wards ; the peccaries, too, have a complex stomach,
while the stomach of the pigs is a simple one with a
cardiac pouch. The peccaries are found in America,
the pigs in the Old World. Among the intermediate
forms elucidating the old relationship was the Titan
pig of India, which was as tallas a horse. The pigmy
hog of India is not much larger than a hare. It is a
curious fact that the young of all the wild pigs are
striped. The most extraordinary pig is the hog-deer
of Celebes and other islands of Malaysia. This is a
hairless species, Babcrusa alfurus, in which the upper
canines grow through the upper lip so as to project
like horns, and often form an almost complete circle,
while the lower canines grow upwards to almost as
great a length.

The last of the Artiodactyls, or even-toed ungu-
lates, are the hippopotami. These are all assigned
to one genus having several species, most of them
extinct, one of them as much larger than 7, appopotamus
amphibius as the mammoth was larger than the
elephant. Two species are living, both of them
African, but fossil hippopotami have been found in
India, in Madagascar, and even in Yorkshire. The
Liberian hippo lives on the West Coast of Africa.
He is a little over two feet high, and under six feet
long. The better known H. amphibius is a giant in
comparison. He can swim, he can dive, he can walk
along the bed of the rivers under water—and he can