Let us turn to the facts, and see how far they fulfil these requirements of the doctrine of evolution.

In Europe abundant remains of horses are found in the Quaternary and later Tertiary strata as far as the Pliocene formation.  But these horses, which are so common in the cave-deposits and in the gravels of Europe, are in all essential respects like existing horses.  And that is true of all the horses of the latter part of the Pliocene epoch.  But, in deposits which belong to the earlier Pliocene and later Miocene epochs, and which occur in Britain, in France, in Germany, in Greece, in India, we find animals which are extremely like horses—­which, in fact, are so similar to horses, that you may follow descriptions given in works upon the anatomy of the horse upon the skeletons of these animals—­but which differ in some important particulars.  For example, the structure of their fore and hind limbs is somewhat different.  The bones which, in the horse, are represented by two splints, imperfect below, are as long as the middle metacarpal and metatarsal bones; and, attached to the extremity of each, is a digit with three joints of the same general character as those of the middle digit, only very much smaller.  These small digits are so disposed that they could have had but very little functional importance, and they must have been rather of the nature of the dew-claws, such as are to be found in many ruminant animals.  The Hipparion, as the extinct European three-toed horse is called, in fact, presents a foot similar to that of the American Protohippus (Fig. 9), except that, in the Hipparion, the smaller digits are situated farther back, and are of smaller proportional size, than in the Protohippus.

The ulna is slightly more distinct than in the horse; and the whole length of it, as a very slender shaft, intimately united with the radius, is completely traceable.  The fibula appears to be in the same condition as in the horse.  The teeth of the Hipparion are essentially similar to those of the horse, but the pattern of the grinders is in some respects a little more complex, and there is a depression on the face of the skull in front of the orbit, which is not seen in existing horses.

In the earlier Miocene, and perhaps the later Eocene deposits of some parts of Europe, another extinct animal has been discovered, which Cuvier, who first described some fragments of it, considered to be a Palaeotherium.  But as further discoveries threw new light upon its structure, it was recognised as a distinct genus, under the name of Anchitherium.

In its general characters, the skeleton of Anchitherium is very similar to that of the horse.  In fact, Lartet and De Blainville called it Palaeotherium equinum or hippoides; and De Christol, in 1847, said that it differed from Hipparion in little more than the characters of its teeth, and gave it the name of Hipparitherium.  Each foot possesses three complete toes; while the lateral toes are much larger in proportion to the middle toe than in Hipparion, and doubtless rested on the ground in ordinary locomotion.