therium d'Orleans_. But it is precisely the _Paloeotherium
d'Orleans_ which is the type of Christol's genus _Hipparitherium_; and
thus, though _Hipparitherium_ is of later date than _Anchitherium_, it
seemed to me to have a sort of equitable right to recognition when this
Address was written. On the whole, however, it seems most convenient to
adopt _Anchitherium_.]

Again, the skeleton of _Anchitherium_ is extremely equine. M. Christol
goes so far as to say that the description of the bones of the horse, or
the ass, current in veterinary works, would fit those of _Anchitherium_.
And, in a general way, this may be true enough; but there are some most
important differences, which, indeed, are justly indicated by the same
careful observer. Thus the ulna is complete throughout, and its shaft is
not a mere rudiment, fused into one bone with the radius. There are three
toes, one large in the middle and one small on each side. The femur is
quite like that of a horse, and has the characteristic fossa above the
external condyle. In the British Museum there is a most instructive
specimen of the leg-bones, showing that the fibula was represented by the
external malleolus and by a flat tongue of bone, which extends up from it
on the outer side of the tibia, and is closely ankylosed with the latter
bone.[3] The hind toes are three, like those of the fore leg; and the
middle metatarsal bone is much less compressed from side to side than
that of the horse.

[Footnote 3: I am indebted to M. Gervais for a specimen which indicates
that the fibula was complete, at any rate, in some cases; and for a very
interesting ramps of a mandible, which shows that, as in the
_Paloeotheria_, the hindermost milk-molar of the lower jaw was devoid of
the posterior lobe which exists in the hindermost true molar.]

In the _Hipparion_, the teeth nearly resemble those of the Horses, though
the crowns of the grinders are not so long; like those of the Horses,
they are abundantly coated with cement. The shaft of the ulna is reduced
to a mere style, ankylosed throughout nearly its whole length with the
radius, and appearing to be little more than a ridge on the surface of
the latter bone until it is carefully examined. The front toes are still
three, but the outer ones are more slender than in _Anchitherium_, and
their hoofs smaller in proportion to that of the middle toe; they are, in
fact, reduced to mere dew-claws, and do not touch the ground. In the leg,