ill finally these two
became mere splints, leaving one large toe or hoof with almost
imperceptible splints, which may be seen on the fetlock of a horse's
skeleton.

You must notice that a horse's foot really begins at the point which
we call his knee in the front legs, and at his hock in his hind legs.
His true knee and elbow are close up to the body. What we call his
foot or hoof is really the end of the strong, broad, middle toe
covered with a hoof, and farther up his foot we can feel two small
splints, which are remains of two other toes.

[Illustration: SKELETON OF HORSE OR ASS.
i, Incisor teeth. g, Grinding teeth, with the gap between the two
as in all grass-feeders. k, Knee. h, Hock or heel. f, Foot. s,
Splints or remains of the two lost toes. e, Elbow. w, Wrist. h,
Hand-bone. t, Middle toe of three joints, 1, 2, 3 forming the
hoof.]

Meanwhile during these long succeeding ages while the foot was
lengthening out into a slender limb the animals became larger, more
powerful, and more swift, the neck and head became longer and more
graceful, the brain-case larger in front and the teeth decreased in
number, so that there is now a large gap between the biting teeth and
the grinding teeth of a horse. Their slender limbs too became more
flexible and fit for running and galloping, till we find the whole
skeleton the same in shape, though not in size, as in our own horses
and asses now.

They did not, however, during all this time remain confined to
America, for, from the time when they arrived at an animal called
_Miohippus_, or lesser horse, which came after the Mesohippus and had
only three toes on each foot, we find their remains in Europe, where
they lived in company with the giraffes, opossums, and monkeys which
roamed over these parts in those ancient times. Then a little later we
find them in Africa and India; so that the horse tribe, represented by
creatures about as large as donkeys, had spread far and wide over the
world.

And now, curiously enough, they began to forsake, or to die out in,
the land of their birth. Why they did so we do not know; but while in
the old world as asses, quaggas, and zebras, and probably horses, they
flourished in Asia, Europe, and Africa, they certainly died out in
America, so that ages afterwards, when that land was discovered, no
animal of the horse tribe was found in it.

And the true horse, where did he arise? Born and bred probably in
Central Asia f