COLL ABED Al. 173 



than the hair of ordinary quadrupeds. It is coarse and 

 flattened at the extremity, but as small at the root as the 

 finest spider's web ; and its dry and withered appearance 

 forms the ai's principal security against its pursuers, as 

 it renders it extremely difficult to detect it whilst at rest 

 among the branches covered with bark and moss of the 

 same colour ; it is only when in motion that it can be 

 readily distinguished from the trunk beneath which it 

 hangs suspended. In other respects, different individuals 

 of this species differ considerably^ from one another, in 

 the shade and disposition of their colours, and in the in- 

 tensit}' of the mark between the shoulders ; some even 

 want this latter mark altogether, others are of a uniform 

 ash-colour over the whole body, and there are others still 

 which have the hair of the head parted in the centre 

 and hanging down upon each side. 



Length of the adult about seventeen or eighteen 

 inches. 



The Collared Ai {Bradypus collaris) is a very distinct 

 species, even in the bony structure of its cranium. Its 

 face is naked and of a black colour ; the hair of its body 

 less flattened and withered-looking than in the common 

 species ; the forehead, temples, chin, throat, and breast 

 covered with reddish or rust-coloured hair, slightly 

 frizzled ; on the crown of the head it is long and yellow, 

 and on the rest of the body pale orange : but the most 

 distinguishing mark of the species is a large black collar 

 which completely surrounds the neck, and from which its 

 specific name of collaris is derived. Beneath this outer 

 coat there is an inner one of very fine fur, which is of a 

 dark-brown colour on the collar, but gradually dimi- 

 nishes in intensity towards the croup, where it is entirely 

 white. 



Both these species feed upon the leaves of trees, and 

 bring forth but a single young one at a birth. When in 

 motion in the forests, they emit a feeble plaintive cry, 

 resembling the word Ai, and which is the origin of the 

 name they bear among the Europeans settled in America. 

 They are extremely retentive of life, and have been seen 

 to move their legs, and exhibit other symptoms of viva* 



VOL. IV. I 



