316 NATURAL HISTORY. 



THE FOSSIL EQUIDJE. 



The living members of the family of Horses are, as we have seen, restricted to the region 

 of the Old World, and were unknown in the Americas and in Australia, when those countries 

 were first discovered. From an examination, however, of their fossil remains, it is evident that 

 in the Pliocene and Pleistocene times Horses were widely distributed in both North and Soutli 

 America. The bones and teeth in caves and river deposits of Europe also show that Wild Horses 

 were very numerous in Europe in the latter age. "We are even able to form an accurate idea of the 

 European Wild Horse from the engravings which the ancient hunters of Reindeer have left behind in 

 caves of Auvergne, Switzerland, and Derbyshire. The outline engraved on a bit of bone or a fragment 

 of antler shows us an animal with a large head, thick neck, and big mane, coarse and clumsy in 

 its points, as might be expected from an aboriginal wild breed not subject to the care and selection of 

 man. The Horse, like the Bison and the Reindeer, formed a large part of the food of these ancient 

 men of the caves, and was not domesticated. The true Horses begin to appear in Europe in the later 

 Pliocene strata. 



In the early Pliocene and late Miocene ages the family of Horses is represented by the HIP- 

 PARIOX, a small, slender, graceful animal, possessed of three well-defined toes, bearing hoofs, on each 

 limb : one strong and large in the middle, while the two lateral toes are so small that they do not 

 extend beyond the fetlock. They may be compared to dew-claws. The teeth are like those of the 

 Horse, but shorter, and the pattern of the enamel on the grinding surface is more complicated. In 

 the early Miocene and late Eocene the ANCHITHEEIUM appears. Its orbit is not so completely en- 

 circled with bone as in the Horses and Hipparion. 



" The shaft of the ulna," writes Pi-ofessor Huxley, " is stouter than in Hipparion, and is less 

 closely united with the radius. The fibula appears at any rate, in some cases to have been a complete 

 though slender bone, the distal end of which is still closely united with the tibia, though much more 

 distinct than in the Hipparions and Horses. In some specimens, however, the middle of the shaft 

 seems to have been incompletely ossified. Not only are there three toes in each foot, as in Hipparion, 

 but the inner and the outer toes are so large that they must have rested upon the ground. Thus, so far as 

 the limbs ai-e concerned, the Anchitherium is just such a step beyond the Hipparion as the Hipparion 

 is beyond the Horse, in the direction of a less specialised quadruped. The teeth are still more 

 divergent from the Equine type. The incisors are smaller in proportion, and their crowns lack the 

 peculiar pit which characterises those of Equus and Hipparion. The first grinder is proportionally 

 much larger, especially in the upper jaw, and, like the other six, has a short crown and no thick coat of 

 cement. The pattern of their crowns is wonderfully simplified. The fore and hind ridges run with 

 but a short obliquity across the crown, and the pillars ai m e little more than enlargements of the ridges, 

 while in the lower jaw these pillars have almost entirely disappeared. But the foremost of the six 

 principal grinders is still somewhat larger than the rest, and the posterior lobe of the last lower molar 

 is small, as in the other Equictae." 



In all those respects in which Anchitherium departs from the modern Equine type it approaches 

 that of the extinct Palceotlieria ; and this is so much the case that Cuvier considered the remains of 

 the Anchitherium, with which he was acquainted, to be those of a species of Palseotherium. From 

 these considerations it may be concluded that the highly specialised Horse has obtained its charac- 

 teristics by descent from the Hipparion, and that again from the Anchitherium. In some cases on 

 record there is a reversion towards the ancestral type, Horses having been born with tridactyle 

 feet, similar in every respect to those of the Hipparion. 



The lineage of the Horse is traceable yet further back by the discoveries of Marsh and Cope in 

 New Mexico, Wyoming, and Utah, in North America, up to the Eohippus of the Lower Eocene, a 

 small animal not larger than a Fox, and with three toes on the hind foot and four and a rudiment of 

 a fifth on the fore foot. It must further be noted that the fossil Horses increased in size as they lost 

 their toes, and that the living Horse is the biggest of the family. 





