46 



GEOLOGY. 



and powerful tail. Whilst in that position it could freely use its 

 strong 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 representa- 

 tive, 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 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 giraffe, 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 

 Megatherium — 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. 



Remains of other allied animals, namely, the Mylodon, the Scelido- 

 therium and the Megalonyx, may be seen in Wall-case 12, and in 

 Table-case No. 14. 



Although so much larger in bulk than their modern representa- 

 tive, 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 

 through which the upper waters of the Parana and Uruguay flowed, the 

 lowlands, which now form the extensive " pampas," or grassy plains, 

 of the La Plata, were probably submerged estuarine, or delta areas, 

 over which these 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 valleys 

 where they had their habitat. Hundreds of the fossil remains of these 

 huge herbivora have been met with in this pampas formation exposed 

 in the beds of the sluggish rivers which now traverse these plains. 



ORDER XII. — MARSUPIAL! A (Kangakoo and Wombat). 



Just as the South American Continent had, in past ages, its 

 peculiar group of colossal animals (Edentata), represented at the 

 present day by the little banded " Armadillo " and the " Tree- 

 Sloth," so the great Island-Continent of Australia had formerly its 

 peculiar indigenous fauna, which lived, flourished and died, probablv 

 before this vast region of the earth had been visited by the human 



