cene period. The accompanying
illustration (fig. 229) represents the notion which the great
Cuvier was induced by his researches to form as to the outward
appearance of _Paloeotherium magnum_. Recent discoveries, however,
have rendered it probable that this restoration is in some important
respects inaccurate. Instead of being bulky, massive, and more
or less resembling the living Tapirs in form, it would rather
appear that _Paloeotherium magnum_ was in reality a slender,
graceful, and long-necked animal, more closely resembling in
general figure a Llama, or certain of the Antelopes.

[Illustration: Fig. 229.--Outline of _Paloeotherium magnum_,
restored. Upper Eocene, Europe. (After Cuvier.)]

The singular genus _Anchitherium_ forms a kind of transition
between the _Paloeotheria_ and the true Horses (_Equidoe_). The
Horse (fig. 230, D) possesses but one fully-developed toe to
each foot, this being terminated by a single broad hoof, and
representing the _middle_ toe--the _third_ of the typical
five-fingered or five-toed limb of Quadrupeds in general. In
addition, however, to this fully-developed toe, each foot in the
horse carries two rudimentary toes which are concealed beneath the
skin, and are known as the "splint-bones." These are respectively
the _second_ and _fourth_ toes, in an aborted condition; and the
first and fifth toes are wholly wanting. In _Hipparion_ (fig.
230, C), the foot is essentially like that of the modern Horses,
except that the second and fourth toes no longer are mere
"splint-bones," hidden beneath the skin; but have now little
hoofs, and hang freely, but uselessly, by the side of the great
middle toe, not being sufficiently developed to reach the ground.
In _Anchitherium_, again (fig. 230, B), the foot is three-toed,
like that of _Hipparion_; but the two lateral toes (the second
and fourth) are so far developed that they now reach the ground.
The _first_ digit (thumb or great toe) is still wanting; as also
is the _fifth_ digit (little finger or little toe). Lastly, the
Eocene rocks have yielded in North America the remains of a small
Equine quadruped, to which Marsh has given the name of _Orohippus_.
In this singular form--which was not larger than a fox--the foot
(fig. 230, A) carries _four_ toes, all of which are hoofed and touch
the ground, but of which the _third_ toe is still the largest. The
_first_ toe (thumb or great toe) is still wanting; but in this
ancient representative of the Ho