tructure of the
massive limbs, except that there are only four toes to each foot.
The upper jaw was devoid of front teeth, but there were two very
large canine teeth, in the form of tusks directed perpendicularly
downwards; and there was also a series of six small molars on each.
Each upper jaw-bone carried a bony projection, which was probably
of the nature of a "horn-core," and was originally sheathed in
horn. Two similar, but smaller, horn-cores are carried on the
nasal bones; and two much larger projections, also probably of
the nature of horn-cores, were carried upon the forehead. We may
thus infer that _Dinoceras_ possessed three pairs of horns, all
of which resembled the horns of the Sheep and Oxen in consisting
of a central bony "core," surrounded by a horny sheath. The nose
was not prolonged into a proboscis or "trunk," as in the existing
Elephants; and the tail was short and slender. Many forms of
the _Dinocerata_ are known; but all these singular and gigantic
quadrupeds appear to have been confined to the North American
continent, and to be restricted to the Eocene period.

[Illustration: Fig. 232.--Skull of _Dinoceras mirabilis_, greatly
reduced. Eocene, North America. (After Marsh.)]

The important order of the Elephants (_Proboscidea_) is also not
known to have come into existence during the Eocene period. On the
other hand, the great order of the Beasts of Prey (_Carnivora_)
is represented in Eocene strata by several forms belonging to
different types. Thus the _Ardocyon_ presents us with an Eocene
Carnivore more or less closely allied to the existing Racoons;
the _Paloeonyctis_ appears to be related to the recent Civet-cats;
the genus _Hyoenodon_ is in some respects comparable to the living
Hyaenas; and the _Canis Parisiensis_ of the gypsum-bearing beds
of Montmartre may perhaps be allied to the Foxes.

[Illustration: Fig. 233.--Portion of the skeleton of _Vespertilio
Parisienis_. Eocene Tertiary, France.]

The order of the Bats (_Cheiroptera_) is represented in Eocene
strata of the Paris basin (Gypseous series of Montmartre) by
the _Vespertilio Parisiensis_ (fig. 233), an insect-eating Bat
very similar to some of the existing European forms. Lastly, the
Eocene deposits have yielded more or less satisfactory evidence
of the existence in Europe at this period of examples of the
orders of the Gnawing Mammals (_Rodentia_), the Insect-eating
Mammals (_Insectivora_), and the Monkeys (_Quadrumana_).[24]