XXV J PERISSODACTYLA 689 



Borneo and in Sumatra (R. sumatrensis\ while in Africa there are 

 several species; the commonest, R. bicornis, is frequently shown 

 in menageries. It is supposed that the idea of the unicorn 

 was derived from the one-horned Rhinoceros, but if this be so the 

 imagination must have played a powerful part in evolving the 

 graceful animal which figures in the royal arms out of the clumsy 

 Rhinoceros. 



The general appearance of the Horse, Equus caballus, is 



Equidae. sufficiently well known, but the structure of its 



feet, which, next to the wings are the most highly 



specialised organs of locomotion in the animal kingdom, demand 



careful attention. 



FIG. 345. Indian Khinoceros, Rhinoceros unicornis. From Wolf. 



The apparent "knees" of the Horse correspond to the joints of 

 the wrist and the ankle, the true elbow and knees are concealed in 

 the body of the animal, although the motion of these joints can be 

 clearly seen if a running Horse be watched. A Horse walks on the 

 very points of its finger and toe-nails, and it possesses only one finger 

 on each hand and one toe on each foot (C, Fig. 344), the fingers and 

 toes corresponding to the outer fingers, the toes of the Rhinoceros 

 being represented merely by bones entirely concealed beneath the 

 skin and applied like splints to the great middle finger and toe 

 respectively. Thus the whole limb instead of being a loosely 

 jointed flexible organ for grasping, becomes a firmly jointed lever 

 bending only in one plane and suitable for quick locomotion. 

 S. & M. 44 



