350 HISTORICAL PALAAONTOLOGY. 
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 Cuviert (fig. 260) of the South American Pampas. 
SS = 
Fig. 260.—Megatherium Cuvieri. 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 vertebree 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 
