286 TYPES OF ANIMAL LIFE 



little toes are the longest and the middle one is the 

 shortest. The toes are webbed, but the hind-limbs are 

 very differently disposed from those of the sea-lion. 

 Every one who has observed a seal's progress on land 

 must have been struck with the singularly awkward and 

 wriggling movement of its body. This is due to the 

 fact that though the seal is a quadruped as regards the 

 number of its limbs, it is no quadruped as regards their 

 use. The sea-lion, as before stated, does walk on all 

 fours — in spite of the little freedom of the hind limbs — 

 and does turn its hind feet forwards, resting on the soles 

 of those feet as it walks. 



The seal, however, is quite unable to turn its hind feet 

 forward at all. Their soles are hairy, and it can never 

 walk on them. On the land, therefore, the seal can only 

 progress by contracting the muscles of its body, and by 

 thus contorting its form, it is able to wriggle over the 

 ground with more or less assistance from the fore-limbs. 

 Nevertheless, it can thus shuffle along, especially over 

 the ice, with surprising speed. Its hind limbs are only 

 useful to it for progression when in the water, and then 

 they are extended backwards, applied together — with 

 sole to sole — and flapped, alternately right and left, 

 so as to serve in the same way as does the tail of a 

 fish. 



Not only are the legs thus permanently bent back- 

 wards, but they are bound together by a fold of skin 

 which also embraces, and is attached to, the sides of the 

 short tail. Little therefore as may be the resemblance 

 or affinity existing between the seal and the bat, there is 

 a certain similarity in the construction of this region of 

 the body in these two very different kinds of beasts. 

 We saw, when considering the structure of the bat,* that 

 * See p. 153. 



