ODD-TOED UNGULATES 



121 



are informed by a traveller who has acquired an intimate knowledge of 

 the horses of the pampas these animals learn to recognise their rider, 

 their harness, the shed in which they have been saddled, etc. ; the same 

 sense enables them to find their way back to their dwelling or pasture on 

 dark nights or in dense fogs. Similar observations may be made in the 

 case of our own domestic breeds. 



2. As a fast runner the horse is a match for any other fleet-footed 

 animal. The arrangements which specially adapt it for speedy loco- 

 motion are 



(a) Its slender shape. When running fast (racing), it stretches for- 

 ward its head and neck, the latter being laterally compressed and adorned 

 with a mane ; the body thus assumes the shape 



of a pointed wedge, which easily cuts through the 

 air. A good racer can accomplish over 900 yards 

 per minute. 



(b) The legs, which are long, light, and at the 

 same time very powerful. 



(c) It walks on the tip of only one toe (corre- 

 sponding to the third in the human hand or foot). 

 (Compare with wolf and ox.) Eudiments of the 

 second and fourth metacarpals and metatarsals are 

 present. The terminal joint of the third toe is 

 very large, and is invested by a hoof like a shoe, 

 thus forming a large surface of support. The 

 animal does not walk upon the whole underside of 

 the hoof, but only on the edge of it and on a ridge 

 (the so-called "frog" of the veterinary) which 

 passes from behind forwards along the concave 

 sole. By means of this hard edge, which is well 



protected against wear, the animal can obtain a ^ 



... FORE-LEG OF THE HORSE. 



firm, support against the inequalities of the surface. .,Humerus; s p ., radius; 

 (This is specially noticeable in cart-horses.) The 

 " frog," which consists of soft horn, acts as a pad 

 which diminishes concussion when the hoofs strike 

 the ground. The elasticity of the horse's gait is 

 due to the angles at which nearly all the joints of 

 the legs are set. The bend is greatest at the fetlock joints between the 

 metacarpals and metatarsals and the digit. (Explain importance of 

 this to the rider.) The hoofs of our horses are shod with iron, which 

 protects them against the excessive wear to which they are subjected on 

 the hard ground of roads, etc. 



3 and 4. Its size and strength are in themselves a means of defence 



E., ulna; Hw., carpal 

 bones ; M. , metacarpal ; 

 1, 2, 3, phalangeal joints 

 (3 is invested like a shoe 

 by the hoof, which is 

 marked in black). 



