THE TWO-TOED SLOTH. 



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of his feet to a bough, and making use of the fourth to reach and 

 convey to his mouth the food on which he lives. The Ai is more 

 indolent in his habits than the Unau, from which he differs rather in his 

 anatomical and osteological characteristics than in his aspect and con- 

 formation. He may, however, be recognized by his rudimentary tail, 

 his flattened visage, and the long frizzled hair which covers certain 

 parts of the body. 



1. Ai (Two-toed Sloth). 



2. Unau (Three-toed Sloth). 



We have seen that the aye-aye may be considered as connecting 

 the Quadrumana with the Bradypes, on the one hand, and the 

 squirrels on the other. These two groups, however, exhibit a very 

 striking contrast between their habits and disposition; and since to 

 animals of the former the name has been given of " Sloths," the latter 

 might justly be designated "the Active." If there exist, indeed, any 

 animals for whom movement is a vital necessity, these, assuredly, are 



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