SLOTHS. 207 



The two-tced sloths, or unaus, of -which there are two well- 

 -defined species, constitute the genus Choloepus, characterised by 

 having only two functional toes on the fore-foot : these two digits representing the 

 index and middle finger of the human hand. The hind-foot has, however, three 

 toes, as in Bradypus. The unaus are further distinguished by the characters 

 of their teeth: the first pair in each jaw being longer and stouter than the 

 others, from which they are separated by a considerable interval These anterior 

 teeth assume, indeed, the characters of tusks, and have their summits obliquely 

 worn awaj* by mutual attrition. That they do not correspond to the true tusks, or 

 canines, of other mammals is shown, however, by the circumstance that the lower 

 ones bite behind, instead of in front of those of the upper jaw. In the common 

 unau (C. didactylus) the number of vertebrae in the neck is the usual seven, 

 but in Hoffmann's sloth (C. hoffmanni) it is reduced to six. Of these two species 

 the former is restricted to Brazil; while the latter extends from Ecuador to Costa 

 Rica. Hoffmann's sloth utters at rare intervals a cry like the bleating of a sheep, 

 while when suddenly seized it gives vent to a loud snort 



The haunts of the sloths are the pri val forests of South and 



Central America, where vegetation attains its highest development, 

 and the warm air is heavily laden with moisture. The darker and denser the 

 forest, the more thickly is it tenanted by these creatures, which are as thoroughly 

 arboreal as the squirrels and spider-monkeys, and seldom or never descend of their 

 own accord to the ground. Indeed, on the ground the sloth is but a helpless 

 creature, walking uneasily on the edges of its in-turned feet, and seeking as soon 

 as possible to regain its native trees. Writing of the habits of the common three- 

 toed sloth {B. tridactylus), Bates observes that the Indians call it ai ybyrete\ or sloth 

 of the mainland, to distinguish it from the B. infuscatvs, which has a long black 

 and tawny stripe between the shoulders, and is called ai ygapo, or sloth of the 

 flooded lam Is. Some travellers in South America have described the sloth as very 

 nimble in its native woods, and have disputed the justness of the name which has 

 been bestowed upon it. "The inhabitants of the Amazon regions, however, both 

 Indians and descendants of the Portuguese, hold to the common opinion, and 

 consider the sloth as the type of laziness. . . It is a strange sight to watch the 

 uncouth creature, fit production of these silent shades, lazily moving from branch 

 to branch. Every movement betrays, not indolence exactly, but extreme caution. 

 He never loosens his hold from one branch without first securing himself to the 

 next, and when he does not find a bough to immediately grasp with the rigid 

 hooks into which his paws are so curiously transformed, he raises his body, 

 supported on his hind-legs, and claws around in search of a fresh foothold." Bates 

 goes on to say that after watching its movements for some time, he shot the 

 specimen under observation ; its body remained, however, firmly suspended to the 

 bough to which it was clinging, and it was not till the muscles became relaxed 

 that it fell. He adds that on another occasion he saw a three-toed sloth swimming 

 a river, about five hundred yards wide. 



Sloths are mainly nocturnal ; and in their usual attitude they hang suspended 

 back downwards. When sleeping, they roll themselves into a ball, with the 

 head tucked between the arms; in this position they somewhat resemble the 



