FAMILY TARDIGRADA ; SLOTHS. 



273 



surface of the ground, is turned towards the body ; so that the 

 animal is obliged to rest upon the side of the hind-foot, and 

 upon the elbow (not upon the extremity) of the fore-limb ; and 

 it can only advance itself, by a most awkward shuffling move- 

 ment ; or by laying hold, with its long crooked claws, of some 

 fixed object, towards which it draws itself. But these peculi- 

 arities ought no more to excite our pity and compassion, than 

 the circumstance of Fishes being deprived of legs, and unable to 

 move upon dry ground; for when the Sloth is placed in its 

 natural condition, they show themselves to be most perfectly 

 adapted to its peculiar mode of existence, for which no other 



animal is equally fitted. 

 When placed in a tree, 

 the Sloth is no longer the 

 slow-moving, piteous- 

 looking, animal which 

 it is commonly reputed ; 

 for it climbs the trunk, 

 and passes from branch 

 to branch, with consi- 

 derable rapidity, having 

 been known to ascend, 

 in a minute, from the 

 bottom to the top of a lofty tree. The only three species of 

 Sloth, at present known to exist, the Ais, or three-toed Sloths, 

 (of which there are two species, slightly differing from each 

 other), and the Unau, or two-toed Sloth, are inhabitants of the 

 dense forests of the tropical portion of South America, the branches 

 of whose trees are so intertangled with one another, that hundreds 

 of miles may be traversed by passing from one tree to another. 

 Clinging by the hinder claws, the posterior limbs securely em- 

 bracing the bough, and generally holding by one of their fore- 

 limbs also, they employ the other to hook towards them the 

 foliage on which they browze. Their long arms, with the firm 

 claws by which they are terminated, enable them to pass from 

 branch to branch, even when these are at some distance from each 

 other; and when they live in the more open parts of the forest, 



FIG. 138 Ai, OR COMMON SLOTH. 



