THE SLOTH 271 



food still more abundantly. The development of the 

 bones of their limbs makes it evident that those limbs 

 were clothed with prodigiously voluminous, and therefore 

 very powerful, muscles. This fact is shown by the 

 huge ridges, and other prominences which stand 

 out from the bones, and served to aflfbrd additional 

 surface for the attachment of such vast muscles. The 

 great haunch bones tell the same story, and the tail itself 

 must have been a most powerful organ, if not for active 

 movement, yet for most efficient support. Activity was 

 doubtless no attribute of these huge beasts, which had 

 nothing to fear from any enemy. Probably their move- 

 ments were little, if at all, more rapid than are the 

 movements of the sloth in our own day. But speed was 

 not required for the mode of procuring food, which the 

 venerable naturalist Owen has suggested. According 

 to him, these creatures raised themselves nearly erect, 

 supporting their ponderous body upon their two bulky 

 hind limbs, and their very powerful tail, as on a tripod. 

 Then with their strong fore-arms, they embraced the 

 trunk of some moderate-sized tree, and proceeded to 

 sway it to and fro, till they succeeded in prostrating it. 

 Thus they would be provided with an ample repast, and 

 their great cutting claws would be most useful for tearing 

 down, or breaking off, those branches of the prostrate 

 tree which were out of their reach, without such action 

 on their part. The single great hooked claw attached to 

 each hind foot was no doubt of great use to them, by 

 giving them a much better and more secure hold on the 

 gi'ound, while struggling to uproot a tree, than they 

 would have had without it. 



We may now attempt to answer the question, " What 

 is a sloth ? " in the light afforded us by our brief review 

 of those forms living and extinct, which naturalists 



