XIV. PALiEONTOLOGY OR FOSSILS. 115 



length. The strength of the Megatherium is indicated by tlie 

 form of the bones, with their surfaces, ridges and crests every- 

 where roughened for the attachment of powerful muscles and 

 tendons. The bony framework of the fore part of the body is 

 comparatively slender, but the hinder quarters display in every 

 part enormous strength and weight combined, indicating that tlie 

 animal habitually rested on its haunches and powerful tail. 

 Whilst in that position it could freely use its stron^^ flexible 

 forearms and the large claws with which its fore feet were 

 provided to break down or uproot the trees upon the leaves and 

 succulent branches of which it fed, like its pigmy modern repre- 

 sentative, the existing Tree Sloth, which spends its entire life 

 climbing back downwards among the branches of the trees. 

 The jaws are destitute of teeth in the front, but there are 

 indications that the snout was elongated, and more or less flexible 

 whilst the fore part of the lower jaw is much prolonged and 



grooved to give support to a long cylindrical, powerful, 



muscular tongue, aided by which the great sloth, like the girafle, 

 could strip off the small branches of the trees, which, by its colossal 

 strength, it had uprooted. In the Elephants, which subsist on 

 similar food to that of the Megatheriiiin — the grinding of the food 

 is effected by molar teeth which are replaced by successional ones 

 as the old are worn away. In the Giant Ground Sloth only one 

 set of teeth were provided, but these by constant upward growth, 

 and continual addition of new matter beneath, lasted as long as 



the animal lived, and never needed renewal Although so 



much larger in bulk than their modern representative, these huge 

 extinct vegetarians of the New World all belong to one family, 

 being classed with the " Great Ant Eaters" in the order 

 Edentata (or toothless animals), but the Ant-eaters are the only 

 ones in the class that have no teeth, the others having teeth in 

 the sides of their jaws but none in front. At the time when 

 these animals lived in the vast wooded regions throui^h which the 

 upper waters of the Parana and Uruguay flowed, the lowlands, 

 which now forms the great ' pampas ' or grassy plains, of tlie La 

 Plata, were probably submerged estuarine, or delta areas, on 

 which the great rivers annually deposited the fine sediment which 

 they brought down, together with the bodies of Megatheria, 

 Mylodons, Glyptodons, &c., drowned during floods in the upper 



