FEET AND HANDS. 



337 



ening out of the one bone (*), which remains as the representative of 

 the " sole " of the foot. Ages ago, as is proved by fossil remains, the 

 forefathers of the horse of to-day had three, four, or even five toes. 

 At a, a, on each side of the great single bone two thin bones can 

 be seen. These two bones are the splint bones, the only remains 

 now to be found of the vanished toes. 



All the animals we have so far mentioned have four feet more 

 or less alike, all being used for the same purpose, that of running. 

 But some animals came to use their 

 fore feet for one purpose and their 

 hind feet for another, and in conse- 

 quence of this the fore feet came to be 

 unlike the hind feet. 



A striking example of such a dif- 

 ference in the use of the fore and hind 

 feet, leading also to a difference in 

 their structure, is found in the kan- 

 garoo, an animal which is seen wild 

 only in Australia, where it hops or 

 leaps over the open country, more or 

 less upright, with extraordinary swift- 

 ness by means of its hind feet alone. 

 When it rests, it sits on the long soles 

 of its hind feet, steadied by its thick 

 tail. Fig. 6 A represents the hind 



foot of a kangaroo in its ordinary position when leaping, and Fig. 

 6 B shows of what strangely changed bones it is composed. One 

 ray has become very long and thick, and another, though not so 

 long, is also fairly thick, but the other two are quite thin, as if they 

 were dying away from not being used. 



The fore feet of the kangaroo (Fig. 6 C) are never used as walk- 

 ing feet except when the animal is hobbling about slowly. Their 

 chief work is grasping and tearing the leaves, grass, or fruit, or dig- 

 ging up the roots which form the food of the kangaroo. They are 

 never needed to support the weight of the body, and so the toes are 

 not large and thick, and four of the five toes are kept. In looking 

 at the fore feet of the kangaroo one is tempted to call them " hands," 

 for this very interesting difference in the use of fore and hind limbs 

 in other animals, such as the monkeys, gave rise gradually to a true 

 grasping hand. 



In a second paper we shall deal with the extraordinary trans- 

 formations of the fore feet into paddles and wings, found in whales, 

 bats, and birds, and shall also see how true hands came to be devel- 

 oped in monkeys and in man. 



VOL. LII. 26 



Fig. 6. 



