s megarhinus_ (fig. 249, B), on the other hand, no
such partition exists between the nostrils, and the nasal bones
are greatly developed in size. It was a two-horned form, and is
found associated with _Elephas meridionalis_ and _E. Antiquus_ in
the Pliocene deposits of the Val d'Arno, near Florence. Like the
preceding, it survived, in diminished numbers, into the earlier
portion of the Post-Pliocene period.

[Illustration: Fig. 249.--A. Under surface of the skull of
_Rhinoceros Etruscus_, one-seventh of the natural size--Pliocene,
Italy.; B, Crowns of the three true molars of the upper jaw, left
side, of _Rhinoceros megarhinus_ (_R. Leptorhinus_, Falconer),
one-half of the natural size--Pliocene, France. (After Falconer.)]

The Horses (_Equidoe_) are represented, both in Europe and America,
by the three-toed Hipparions, which survive from the Miocene,
but are now verging upon extinction. For the first time, also,
we meet with genuine Horses (_Equus_), in which each foot is
provided with a single complete toe only, encased in a single
broad hoof. One of the American species of this period (the _Equus
excelsus_) quite equalled the modern Horse in stature; and it
is interesting to note the occurrence of indigenous horses in
America at such a comparatively late geological epoch, seeing
that this continent certainly possessed none of these animals
when first discovered by the Spaniards.

Amongst the Even-toed Ungulates, we may note the occurrence of
Swine (_Suida_), of forms allied to the Camels (_Camelidoe_), and
of various kinds of Deer (_Cervidoe_); but the most interesting
Pliocene Mammal belonging to this section is the great _Hippopotamus
major_ of Britain and Europe. This well-known species is very
closely allied to the living _Hippopotamus amphibius_ of Africa,
from which it is separated only by its larger dimensions, and by
certain points connected with the conformation of the skeleton.
It is found very abundantly in the Pliocene deposits of Italy and
France, associated with the remains of the Elephant, Mastodon,
and Rhinoceros, and it survived into the earlier portion of the
Post-Pliocene period. During this last-mentioned period, it extended
its range northwards, and is found associated with the Reindeer,
the Bison, and other northern animals. From this fact it has been
inferred, with great probability, that the _Hippotamus major_
was furnished with a long coat of hair and fur, thus differing
from its nearly