184 



BRANCH VERTEBRATA. 



\ w 



resembles the mole in its habits. Its short tail, bent 

 under the body, serves to make a tripod with the fore 

 feet, " while the hind feet are set to work simultaneously, 

 discharging the sand with incredible swiftness. 



The Sloths* are naturally divided into the two-toed 

 and three-toed. They are peculiar in having the num- 

 ber of cervical vertebrae 

 different from the nor- 

 mal, one of the two- 

 toed having six, while 

 the three-toed have nine. 

 All other mammals, with 

 the single exception of 

 the Sirenia (si re'm a), 

 invariably have seven. 



The hair is of a peculiar 



texture, counterfeiting the masses of moss which drape 

 the tropical forests, and is given a green hue by the 

 presence of a small plant which grows attached to it. 

 They are found only in the tropical regions of the New 

 World. The Ai, so called from its cry, lives on the under 

 side of the branches of trees, even sleeping suspended 

 back downward. Its elongated arms are of use in reach- 

 ing for boughs, the succulent leaves of which it draws 

 to itself for food. 



The Giant Ant-eater of South America has toothless 



Brad' y> pus tri dac' tfy lus. 

 Ai, or Three-toed Sloth. ( T 1 5 .) 



* Cuvier said of this family, " Nature seems to have amused herself in pro- 

 ducing something imperfect and grotesque." Their fore legs are so much larger 

 than their hind ones, that when they try to walk on the ground, they have to 

 drag themselves along on their knees, and they seem awkward enough ; but 

 when moving on the forest-trees they are seen to be well adapted to their in- 

 tended life. In avoiding pursuit, they swing from limb to limb with great 

 rapidity, particularly in a gale of wind, when the branches are swaying toward 

 one another. Their flesh is good eating, and they are obliged to remain con- 

 stantly in the tree-tops to escape their numerous enemies, 



