THE SLOTH.- (Bradypus.) 



* 



PLATE X . T HE SLOTH. 



OF this quadruped, there are two species ; the Ai, and 

 the Unau. It is called Sloth on account of its difficulty in 

 walking. 



The Unau, or two-toed Sloth, has no tail, and only two 

 nails on the fore feet. The Ai, or three-toed Sloth, has a 

 short tail, and three nails on every foot. The nose of the 

 Unau is likewise much longer, the forehead higher, and 

 the ears longer than those of the Ai. It differs also in the 

 hair. As for its interior, its viscera are both formed and 

 situated differently ; but the most distinctive, and, at the 

 same time, the most singular character, is, that the Unau 

 has forty-six ribs, while the Ai has but twenty-eight. 

 This alone supposes two species, quite distinct one from 

 the other ; and these forty-six ribs, in an animal whose 

 body is so short, is a kind of excess or error in nature ; for, 

 even in the largest animals, and those whose bodies are 

 relatively longer than they are thick, not one of them is 

 found to have so many. The elephant has only forty, the 

 dog twenty-six, and the human species twenty- four, &c. 

 This difference in the construction of the Unau and the 

 Ai supposes a greater difference between these two kinds 

 than there is between that of the cat and the dog, which 

 have the same number of ribs ; for the external differences 

 are nothing in comparison with the internal ones, which 

 are the causes of the others. These animals have neither 

 incisive nor canine teeth ; their eyes are dull and heavy ; 

 their mouths wide and thick ; their fur coarse and staring, 

 and like dried grass ; their thighs seem almost disjointed 

 from the haunch ; their legs very short, and badly shaped ; 

 they have no soles to the feet, nor toes separately movea- 

 ble, but only two or three claws excessively long, and 

 crooked downwards and backwards. Unfurnished with 



