390 



PALEONTOLOGY 



from the fore part of the skull to the end of the tail, 11 feet. 

 It was discovered buried 12 feet deep in the fluviatile depo- 

 sits seven leagues north of the city of Buenos Ayres in the 

 year 1841. It forms the subject of a vork entitled, Descrip- 

 tion of the Skeleton of an Extinct Gigantic Sloth (Mylodon 

 robushis)* in which are set forth in detail the grounds for 

 regarding it as a member of the same natural family as the 

 present small arboreal sloth, and as being modified to obtain 

 its leafy food by uprooting and prostrating trees. 



A still larger species of terrestrial sloth (Megatherium) co- 

 existed with the Mylodon in South America. Its skeleton, now 

 complete in the British Museum, measures 18 feet ; its dentition 



Fig. 135. 



Section of upper molar teeth, Megatherium (one-third nat. size). Pleistocene, 



South America. 



agrees as to number and kind of teeth with thai of the sloths 

 (Bradypus). But the molars (fig. L3o) are Longer, more deeply 

 implanted, of more complex structure, and with grinding 



: Lto, 1842, Van Voorst. 



