192 MARVELS OF THE ANIMAL WORLD 



creatures have five toes on the fore-feet and bnt 

 four on the hind ones. With the ruminating 

 animals such as the cattle and the deer, the number 

 is reduced to two on each foot ; and in the horse 

 and its kindred only the middle one remains, which 

 is enclosed in a solid sheath and forms a hoof. 



Then, again, amongst the carnivorous mammals 

 we find that the various types differ in the manner 

 in which they apply their feet to the ground : 

 those which walk entirely upon their toes being 

 called digitigrades, those which apply the sole of 

 their feet to the ground being termed plantigrades, 

 and those in which the limbs assume the form of 

 flippers, as exemplified by the seals, the sea-lions, 

 and the walrus, being known as pinnipeds. Al- 

 though the two last-mentioned beasts can walk 

 upon land, yet their movements when thus engaged 

 are extremely ungainly and laboured ; but when 

 swimming in the water they progress with great 

 facility and rapidity. The limbs of the walrui 

 and sea-lions differ from those of the other pinnipeds ; 

 for whereas in the seals the hinder pair are per- 

 manently directed backwards, and the flapper- 

 like fore -limbs are too short and immobile to be of 

 any assistance in supporting the bodies of the 

 creatures, with the result that, when moving on dry 

 land, they can only wriggle along by moving their 

 bodies in a series of jerky motions, yet the limbs 

 of the sea-lions and walrus can be flexed to a con- 

 siderable degree, the hind legs being turned 

 forwards beneath the body and the fore -legs bent 

 at the joint so that the lower portion of the limbs 



