ITS NEAREST EXISTING RELATIONS. 77 



closely related to the asses, are distinguished from 

 them and associated together by their style of color- 

 ing and geographical distribution, it scarcely seems 

 desirable that such distinctions should be made the 

 ground of difference of generic appellation, and they 

 will in this work all be spoken of as members of the 

 genus Equus. 



THE HORSE (Equus cdbdttus, Linn.) is distin- 

 guished from all the others by the long hairs of the 

 tail being more abundant and growing quite from 

 the base as well as the end and sides, and also by 

 possessing a small bare callosity on the inner side of 

 the hind leg, just below the "hock" or heel-joint, in 

 addition to the one on the inner side of the fore- 

 arm, above the wrist or "knee," common to all the 

 genus. The mane is also longer and more flowing, 

 the front part of it drooping over the forehead, 

 constituting the " forelock " j and the ears are shorter, 

 the limbs longer, the feet broader, and the head 

 smaller. 



Though the existing horses are usually not marked 

 in any definite manner, or only irregularly dappled 

 (i.e. marked with large light spots surrounded by a 

 darker ring), many examples are met with showing 

 a dark streak running along the center of the back, 

 like that found in all other members of the genus, 

 and even with dark stripes on the shoulder and legs. 



