SLOTHS. 357 



only when absolutely compelled to do so. Whilst the name of 

 'sloth' may thus appear to be a merited one from the point 

 of view of a terrestrial mammal, it is wholly undeserved when 

 the animal is looked upon as especially adapted for an arboreal 

 existence." * 



Mr. Waterton saysj that in the forest "he travels at a good 

 round pace, and were you to see him, as I have done, passing 

 from tree to tree, you would never think of calling him a sloth." 



M. Liais remarks % there are two families — the Unau 

 {CholcBpus, lUiger) and the Ai {Achczus, F. Cuvier). The Unau 

 of Buffon has two species, of which only one is spread through 

 the forests of Brazil, especially in the north — Bradypus didactylus 

 (Linn.), native name preguiga (idleness). It is the largest of the 

 sloths, being thirty inches in length. It can swim across large 

 rivers. It never quits the branches of a cecropia until it has 

 devoured all the leaves. The females carry the young on their 

 belly. This animal is generally nocturnal j when it moves during 

 the day, it is much slower than at night. 



Of the genus Ai (Buffon), the oldest known species is the 

 Bradypus tridadylus (Linn.), native name preguiga ay-ay.§ Its 

 length is about half that of the Unau. It is found in North 

 Brazil and in the Guianas. The "Ai with the burnt back," 

 B. ustus (Linn.), is smaller than the last named, and its fur is 

 blacker. 



The collared sloth is the B. torquatus, IlHger, B. Collaris, 

 Desm., AchcEus torquatus, Prince Max. 



These two last-named species are found in the forest regions 

 of Minas Geraes, Espirito Santo, Bahia, and Pernambuco. I 

 heard of their inhabiting the lower regions of the Rio Para, near 

 the Rio Sao Francisco. 



The whole family of sloths may be said to be parasites of the 

 cecropias, || for the leaves of those trees form almost entirely 



* "Manual of Zoology," Dr. AUeyne Nicholson, p. 409, 

 t ' ' Wanderings in South America. " 

 X " Climats, Faune," etc., pp. 338, et seq. 

 § So called from its plaintive cry of " ai-ai." 



II They are called bicho do Embaiiba (beast of the cecropia tree) by the 

 natives. — H. W. Bates, "The Naturalist on the River Amazons," vol. ii. p. 56. 



