POSITION AND STRUCTURE OF HORSE 17 



or outer leg-bone which is as long as, and 

 separate from the radius in less specialised animals, 

 such as rhinoceroses being represented only by its 

 upper end, corresponding to the human elbow, or 

 olecranon, and this being immovably soldered to the 

 radius. In consequence of this welding of two 

 originally separate bones into a single compound 

 element, the fore-leg of a horse is capable of no 

 other movement than a backwards and forwards 

 one ; this being all that is needed by a running 

 animal. A similar consolidation and simplification 

 of elements likewise obtains in the middle segment 

 of the hind-leg of the horse, in which the originally 

 distinct smaller bone known as the fibula is re- 

 duced to its upper extremity, this being firmly 

 welded to the upper end of the larger bone, or 

 tibia. 



The reduction in the number of toes to a single 

 large one in each foot, and of the metacarpal and 

 metatarsal bones to the aforesaid splints, coupled 

 with the elongation of the bones of the whole lower 

 segment of the limb, the simplification and con- 

 solidation of those of the middle segment, and the 

 raising of the carpus (" knee ") and tarsus (hock) far 

 above the level of the ground, so as to cause the 

 animal to walk on the tips of its single toes, are 

 the chief features in which the skeleton of the horse 

 shows (as compared with that of more generalised 



animals) special adaptation for the attainment of a 



B 



