350 HISTORICAL PALAEONTOLOGY. 



singular for the limited geographical range of its members, 

 their curious habits of life, and the well-marked peculiarities 

 of their anatomical structure. South America is the metropo- 

 lis of the existing forms ; and it is an interesting fact that there 

 flourished within Post-Pliocene times in this continent, and to 

 some extent in North America also, a marvellous group of ex- 

 tinct Edentates, representing the living Sloths and Armadillos, 

 but of gigantic size. The most celebrated of these is the huge 

 Megatherium Cuvieri (fig. 260) of the South American Pampas. 



Fig. 260. Megatherium Cuv'eri. Post-Pliocene, South America. 



The Megathere was a colossal Sloth-like animal which attained 

 a length of from twelve to eighteen feet, with bones more mas- 

 sive than those of the Elephant. Thus the thigh-bone is 

 nearly thrice the thickness of the same bone in the largest 

 of existing Elephants, its circumference at its narrowest point 

 nearly equalling its total length ; the massive bones of the 

 shank (tibia and fibula) are amalgamated at their extremities ; 

 the heel-bone (calcaneum) is nearly half a yard in length ; the 

 haunch-bones (ilia) are from four to five feet across at their 

 crests ; and the bodies of the vertebrae at the root of the tail 

 are from five to seven inches in diameter, from which it has 

 been computed that the circumference of the tail at this part 

 might have been from five to six feet. The length of the fore- 

 foot is about a yard, and the toes are armed with powerful 

 curved claws. It is known now that the Megathere, in spite 

 of its enormous weight and ponderous construction, walked, 

 like the existing Ant-eaters and Sloths, upon the outside edge 

 of the fore-feet, with the claws more or less bent inwards 



