HISTORY OP THE EDENTATA 597 



as tapirs. There was a wonderful variety of fglyptodonts, 

 most of them enormous creatures, of which no less than five 

 genera have been collected in Argentiiia and Brazil, and the 

 tground-sloths were even more numerous and varied. Nine 

 genera, with many species, of these great beasts, which ranged 

 in size from an elephant to a tapir, are already known and no 

 doubt the list is still incomplete. These fglyptodonts and 

 fgroimd-sloths must have been among the most conspicuous 

 elements of the Pleistocene fauna. 



Aside from certain problematical Eocene forms, the first 

 North American edentates, which were immigrants from the 

 southern continent, appeared probably in the middle Miocene 

 of Oregon in the form of fground-sloths, but the specimen, 

 as well as a similar one from the lower Pliocene of Nebraska, 

 is not sufficiently complete for positive reference. In the 

 middle PUocene the fground-sloths and fgljTtodonts were 

 unquestionably present, and in the Pleistocene these two sub- 

 orders were niunerously and conspicuously represented. Three 

 or four genera of the huge, elephantine fground-sloths co- 

 existed in Pleistocene North America. ^Megalonyx was 

 abundant in the forested regions east of the Mississippi, from 

 Pennsylvania southward, and on the Pacific coast ; ^Mylodon 

 was transcontinental in distribution ; while ^Megatherium was 

 apparently confined to the southern states. While all three 

 genera imdoubtedly originated in South America, \Megalonyx 

 has not yet been found in that continent. 



This genus was originally named by President Jefferson in 

 1805 from an imgual phalanx found in a cave in Virginia, and he 

 imagined that it belonged to a colossal hon which must still 

 be hving in the mountains of western Virginia. This was 

 deduced from the assumption that no species could become 

 extinct, and the passage is of interest as showing the prevalent 

 belief of the time, although Cuvier had already demonstrated 

 that many species had actually been extinguished. The pas- 

 sage is as follows : "The movements of natm-e are in a never 



