128 MAMMALIA ORDER VI.UNGULATA. 



The ears are elongated ; the long and tapering tail may be either long-haired 

 throughout its length, or only at the tip ; and the neck is ornamented with 

 an upright or flowing mane. Horses are now restricted to the Old World, 

 although they formerly existed both in the northern and southern halves of 

 the New World. 



The common or true horse (Equus caballus) is now best known in a domes- 

 ticated or half-wild condition, although it is probable that the wild horses, 

 or tarpans, of the Russian steppes, are the direct descendants of the original 

 primitive stock, and have never been domesticated. From the other species 

 of the genus the horse is distinguished by the tail being covered with abun- 

 dant long hair from root to tip, by the presence of a warty callosity on each 

 hind-leg, just below the inner side of the ankle-joint, the longer and pendant 

 mane, snorter ears, more elongated limbs, smaller head, and wider hoofs. 

 Some doubt exists whether the horse from Central Asia described as E. 

 prezevalskii is a valid species ; but if it be, it appears to be intermediate 

 between the horse and the asses, having callosities on both limbs, an erect 

 mane, no forelock, small ears, and the upper part of the tail short-haired. 



The zebras of Africa south of the Sahara form a group closely allied to 

 the asses, but distinguished by th.eir more or less completely striped colora- 

 tion. Of these the true, or moun- 

 tain zebra (E. zebra) formerly in- 

 habited the mountains of the Cape 

 Colony in large herds, but is now 

 greatly reduced in numbers. It is 

 a rather small species, standing 

 about four feet at the withers, with 

 rather long ears, the lower part of 

 the tail somewhat thinly clothed 

 with long hairs, and a short mane ; 

 the ground colour being white, with 

 broad, black, transverse stripes, ex- 

 tending over the whole skin, except 

 that of the under-parts and the inner 

 surface of the thighs, and the lower 

 Fig. TO.-BURCHELL'S ZEBRA (Eqiius burchelli). part of the face chestnut brown. 



On the hind-quarters short trans- 

 verse stripes extend from the longitudinal one running down the spine 

 towards or to the oblique ones of the haunches. Grevy's zebra (E. grevyi), 

 of the Galla country, differs by the much narrower and more numerous 

 stripes, especially those of the head, the spine-stripe being disconnected 

 from the others. More distinct is the larger BurchelPs zebra (E. burchelli), 

 from the open plains to the north of the Orange River, characterised by the 

 pale yellowish-brown ground-colour of the hair, and the broad brown or 

 black stripes ; a dark stripe, to which the lateral stripes may be united, 

 traversing the middle line of the under-surface of the body, and the spinal 

 stripe being isolated from the uppermost haunch-stripe parallel to it. Very 

 generally faint stripes occupy the middle of the broad intervals between the 

 dark stripes of the haunches ; and the limbs and tail may be either fully or 

 partially striped, or uniform. Upon such variations several nominal species 

 have been established, but it appears preferable to look upon all these in the 

 light of mere varieties of a single variable species. Many attempts have 

 been made, with more or less marked success, to break this zebra to harness. 



