566 MANUAL OF ZOOLOGY. 



animals which are exclusively confined to South America, in- 

 habiting the vast primeval forests of that continent. The 

 Sloths have a remarkably short and rounded face, and the 

 body is covered with hair. The incisor teeth are altogether 

 wanting, but there are always simple molars, and in the Two- 

 toed Sloth or Unau the first tooth in each jaw on each side is 

 so much larger than the others, and so much more pointed, 

 that it has been regarded as a canine. The stomach is com- 

 plex, somewhat resembling that of the Ruminants. The cer- 

 vical vertebrae are generally regarded as being more than the 

 normal seven in number in the Three-toed Sloth, and the long 

 bones have no medullary cavities. The most striking pecu- 

 liarities, however, about the Sloths are connected with their 

 mode of life. The Sloths, in fact, are constructed to pass 

 their life suspended from the- under surface of the branches 



Fig. 241. Hand of Three-toed Sloth (Bradypus tridactyhis)*Stet Owen. 



of the trees amongst which they live ; and for this end their 

 organisation is singularly adapted. The fore-limbs are much 

 longer than the hind-limbs, and the bones of the fore-arm are 

 unusually movable. All the feet, but especially the fore-feet, 

 are furnished with enormously long curved claws (fig. 241), by 

 the aid of which the animal is enabled to move about freely 

 suspended back downwards from the branches. Not only is 

 this the ordinary mode of progression amongst the Sloths, but 

 even in sleep the animal appears to retain this apparently un- 

 natural position. 



Owing to the disproportionate size of the fore-limbs as com- 

 pared with the hind-limbs, and. owing to the fact that the hind- 

 feet are so curved as to render it impossible to apply the sole 

 to the ground, the Sloth is an extremely awkward animal upon 

 the ground, and it has therefore recourse to terrestrial progres- 



