THE HORSE 



153 



cats and the dogs, walk on all of their toes. In some 

 mammals there is a variation in the number of the tots. 

 For example, the cow 

 walks on two toes and 

 the horse on one toe, 

 the hoof being a modi- 

 fied toe nail. In such 

 cases the other toes are 

 entirely lacking or rudi- 

 mentary (not perfectly 

 developed). 



140. The Horse.— The 

 horse is interesting be- 

 cause it has been associ- 

 ated with man since 

 the pre-historic period 

 known as the Stone Ace. 



Figure 166. — Deer Mouse. 

 A nocturnal rodent. 



It has been suggested that man 



"first hunted horses for food, then drove them, and finally 



Figure 167. — Sea Lions. 



