THE SLOTH 273 



In that extensive group of huge creatures which, 

 since it contains the megatherium and all creatures like 

 it, may be spoken of as the group of " Megatherioids," we 

 find animals which, at one and the same time, resemble 

 both ant-eaters and sloths. On the principles of evolu- 

 tion then we may regard them as at least nearly allied 

 to that parent form in which both sloths and ant-eaters 

 had their first origin. From some more or less mega- 

 therium-like animals there was gradually evolved a 

 creature on the way to elongate its snout and tongue, 

 lose its teeth, augment its tail, and live on animal food. 

 From such a form there must also have been gradually 

 evolved some creature on the way to dwindle strangely 

 in size, to shorten its tail, to simplify its teeth, to 

 elongate its arms, and to diminish the number of its toes, 

 which grew more and more rigid as the animal's race 

 took more and more to climb up the trees, no single 

 branch of which it could any longer hope to be able to 

 pull down. Meantime the troops of great megatherioid 

 animals fell off in numbers, and finally disappeared 

 from the earth's surface (as the glyptodons have also 

 done) and in an as yet quite inexplicable manner, leaving 

 in their place the groups of smaller creatures, difterent 

 indeed as to size, but more exceptionally and specially 

 diversified in structure, than were the gigantic ancestors 

 from which they may boast to have sprung. 



A sloth then is the animal of all beasts the most 

 exclusively organised to dwell in trees and live upon 

 their foliage. It is one of the last evolved of a group of 

 beasts, the most remote and unknown ancestors of which 

 may have given origin to the pangolins and possibly also 

 the aard-vark. Other unknown ancestors less remote 

 were the source whence sprang the parents of the 

 armadillos on the one hand, and the megatheiioids on 



s 



