VERTEBRATA : MAMMALIA. 6/9 



whilst the Post-pliocene sands and gravels of the open country 

 have yielded the bones of various huge Edentates, resembling 

 the Sloths in most essential respects, but adapted for a terres- 

 trial instead of an arboreal life. Of these great " Ground- 

 sloths" (Gravigrada), the most remarkable are the Megathe- 

 rium (fig. 376), which attained a length of eighteen feet, with 



Fig. 376. Skeleton of Megatherium. Post-tertiary, South America. 



bones as massive as, or more so than, those of the Elephant ; 

 and the Mylodon and Megalonyx, both of which extended their 

 range into the United States. 



In the same way the little banded Armadillos of South 

 America were formerly represented by gigantic species, con- 

 stituting the genus Glyptodon. The Glyptodons (fig. 377) dif- 



Fig- 377. Glyptodon clavipes. Pleistocene deposits of South America. 



fered from the living Armadillos in having no bands in their 

 armour, so that they must have been unable to roll themselves 

 up. It is rare at the present day to meet with any Armadillo 

 over two or three feet in length ; but the length of the Glyp- 

 todon clavipes, from the tip of the snout to the end of the tail, 

 was more than nine feet. 



The trunk-armour of Glyptodon is formed of nearly hexagonal 

 bony scutes, forming a massive dome, for the support of which 

 the skeleton is specially modified. Thus the last cervical 



