336 MAMMALS 



back out of the way, thus exposing the claws so necessary 

 for digging its burrows. The spiny ant-eater is furnished 

 with strong claws for tearing open the ants' nests. In 

 addition, it has a long, sticky, extensile tongue with which 

 it can lick up the ants by the hundred and thus obtain a 

 meal. 



The sloth passes its existence in trees. Yet how curiously 

 adapted to such a life it is. What wonderful muscles it 

 must have never to weary of hanging down, either in its 

 waking or sleeping moments. Try the experiment of hold- 

 ing your own weight by suspending yourself from a bar, 

 by your arms, for five minutes. It will give an idea of 

 what the sloth's mode of life means to its muscles. Note 

 that the claws are also modified for grasping the branches. 

 Many sloths possess hair resembling leaves in color, thus 

 affording them protection. I suspect they were driven to 

 such a mode of living partly for the sake of protection. The 

 armadillo, however, which belongs to the same order, in- 

 stead of climbing trees took upon himself a coat of armor, 

 . so flexible that he can roll up inside of it for protection. 



Perhaps among mammals the most remarkable modi- 

 fications and adaptations are found among the whales. 

 As a class, mammals are terrestrial; but here we find an 

 order which is wholly water-living. They are so far modi- 

 fied as to have lost one pair of legs, wholly unfitting them 

 for a terrestrial life ; and the second pair is modified into 

 very efficient paddles. Again, the tail is adapted to swim- 

 ming, and the body is covered with a very thick layer of fat 

 to protect them from the intense cold met with in their 

 habitats. The bowhead whale has no teeth and a very 

 small throat, hence cannot live on large animals or on gross 

 vegetable bodies. It, however, has an enormously capa- 



