The horse family of the present day is divided, like most other families, into two factions, which may be described for variety's sake as those of the true horses and the donkeys, these latter including also the zebras, quaggas, and various other unfamiliar creatures whose names, in very choice Latin, are only known to the more diligent visitors at the Sunday Zoo. Now everybody must have noticed that the chief broad distinction between these two great groups consists in the feathering of the tail. The domestic donkey, with his near congeners, the zebra and co., have smooth short-haired tails, ending in a single bunch or fly-whisk of long hairs collected together in a tufted bundle at the extreme tip. The horse, on the other hand, besides having horny patches or callosities on both fore and hind legs, while the donkeys have them on the fore legs only, has a hairy tail, in which the long hairs are almost equally distributed from top to bottom, thus giving it its peculiarly bushy and brushy appearance. But Prjevalsky's horse, as one would naturally expect from an early intermediate form, stands half-way in this respect between the two groups, and acts the thankless part of a family mediator; for it has most of its long tail-hairs collected in a final flourish, like the donkey, but several of them spring from the middle distance, as in the genuine Arab, though never from the very top, thus showing an approach to the true horsey habit without actually attaining that final pinnacle of equine glory. So far as one can make out from the somewhat rude handicraft of my prehistoric Phidias the horse of the quaternary epoch had much the same caudal peculiarity; his tail was bushy, but only in the lower half. He was still in the intermediate stage between horse and donkey, a natural mule still struggling up aspiringly toward perfect horsehood. In all other matters the two creatures--the cave man's horse and Prjevalsky's--closely agree. Both display large heads, thick necks, coarse manes, and a general disregard of 'points' which would strike disgust and dismay into the stout breasts of Messrs. Tattersall. In fact over a T.Y.C. it may be confidently asserted, in the pure Saxon of the sporting papers, that Prjevalsky's and the cave man's lot wouldn't be in it. Nevertheless a candid critic would be forced to admit that, in spite of clumsiness, they both mean staying.