POSITION AND STRUCTURE OF HORSE 5 



ungulates, or Artiodactyla, as typified by the ox, 

 and an equivalent, albeit at the present day much 

 smaller section, known as the odd-toed ungulates, or 

 Perissodactyla, of which the horse and its relatives 

 are the most specialised members. Although the 

 leading points of distinction between these sub- 

 orders have been indicated in my volume on the ox, 

 it is advisable that the characteristics of the second 

 should be repeated, as well as somewhat amplified, 

 in this place. 



The odd-toed, or perissodactyle, ungulates take 

 their name from the circumstance that the toe 

 corresponding to the middle finger of the human 

 hand and its representative in the hind-limb, to- 

 gether with the bone known as metacarpal in 

 the fore, and metatarsal in the hind leg, respec- 

 tively form the continuation of the main axis of 

 the limb, and are symmetrical in themselves. In 

 the horse and its immediate relatives this middle 

 toe is alone functionally developed in both the front 

 and hind legs ; but in the rhinoceroses, which 

 belong to the same sub-order, although to a different 

 family (Rkinocerotid^), there is a pair of smaller 

 lateral toes, each of which, together with its 

 supporting metacarpal or metatarsal bone, is like- 

 wise symmetrical. Just as the middle toe of the 

 fore-leg corresponds to the middle or third finger of 

 the human hand, so the lateral toes of the rhinoceros 

 severally represent the second and fourth fingers 



