The Domestic Ass, so common to-day in these islands, is of African origin, and has, moreover, departed but little in either form or colour from the wild race. This is probably due to the fact that the ass has not been subjected in this country to that process of rigorous and careful selection that the horse has undergone.
We have no record of its first introduction to these islands, but it was certainly known in the reign of Ethelred, though it was a rare animal. Later it appears to have died out, and to have been reintroduced in the reign of Elizabeth; but it has never become popular. This is unfortunate; its sterling qualities have never been really appreciated by us. Spain, Italy, and Malta have all succeeded in raising some fine breeds. The United States has, however, produced the finest of all in animals standing some 15 or 16 hands (5 feet or 5 feet 4 inches) high.
Mules.
The term Mule, strictly speaking, should be reserved for the offspring of the male ass and the mare: the offspring of the opposite cross is called the Hinny. Mules are valued on account of their great powers of endurance and their sure-footedness. The finest and handsomest are bred in Spain, the United States, and North-west India.
It is interesting to note that mules exhibit a strong tendency to revert to the dun-coloured and striped coloration believed to belong to the primitive horses. The spinal and shoulder stripes which sometimes appear in horses, and more frequently in asses, occur yet more frequently in mules. The legs of the mules appear particularly liable to revert to this striped coloration in the United States, it is said nine out of ten being so marked.
CHAPTER XIII.
THE HOLLOW-HORNED RUMINANTS: OXEN, BISON, BUFFALOES, AND MUSK-OX.
Cattle, Deer, Camels, Pigs, Horses, Tapirs, Rhinoceroses, and Elephants differ greatly in structure from the orders already described. They are classed as the Ungulates, or Hoofed Mammals. In most of these, such as the Horse, Deer, and Oxen, the toes are contained within a solid hoof; in others, such as the Rhinoceros, they are protected by broad nails. Great differences exist in the feet of the various groups of Ungulates, caused by the degree in which the digits, or "toes," remain in use or not. Except in the Elephant, where there are five, the greatest number of "working" digits found in existing forms is four. In the Horse and its surviving allies the digits are reduced to one; in the Giraffes, to two.
The general process, as it can be learnt from the remains of the horse-like animals of the past, seems to have been as follows. One or more of the toes were developed in length and strength at the expense of the others, until, in the case of the Horse, only one toe remained, which was enclosed in a large and solid hoof, little splints on either side of the cannon-bone being left to hint where the second and fourth toes had once been. In the Oxen and Deer the third and fourth toes developed equally, at the expense of the others, and each gained a case or covering, which makes the two parts of the "cloven hoof" of these groups.