88 BAHIA BLANCA chap. 



the mammalia is upon the whole inferior to that of the 

 testacea." ^ 



The great size of the bones of the Megatheroid animals, 

 including the Megatherium, Megalonyx, Scelidotherium, and 

 Mylodon, is truly wonderful. The habits of life of these 

 animals were a complete puzzle to naturalists, until Professor 

 Owen ^ solved the problem with remarkable ingenuity. The 

 teeth indicate, by their simple structure, that these Megatheroid 

 animals lived on vegetable food, and probably on the leaves and 

 small twigs of trees ; their ponderous forms and great strong 

 curved claws seem so little adapted for locomotion, that some 

 eminent naturalists have actually believed that, like the sloths, 

 to which they are intimately related, they subsisted by climbing 

 back downwards on trees, and feeding on the leaves. It was 

 a bold, not to say preposterous, idea to conceive even ante- 

 diluvian trees, with branches strong enough to bear animals as 

 large as elephants. Professor Owen, with far more probability, 

 believes that, instead of climbing on the trees, they pulled the 

 branches down to them, and tore up the smaller ones by the 

 roots, and so fed on the leaves. The colossal breadth and 

 weight of their hinder quarters, which can hardly be imagined 

 without having been seen, become, on this view, of obvious service, 

 instead of being an encumbrance : their apparent clumsiness 

 disappears. With their great tails and their huge heels firmly 

 fixed like a tripod on the ground, they could freely exert the 

 full force of their most powerful arms and great claws. Strongly 

 rooted, indeed, must that tree have been, which could have 

 resisted such force ! The Mylodon, moreover, was furnished 

 with a long extensile tongue like that of the giraffe, which, by 

 one of those beautiful provisions of nature, thus reaches with 

 the aid of its long neck its leafy food. I may remark, that in 

 Abyssinia the elephant, according to Bruce, when it cannot 

 reach with its proboscis the branches, deeply scores with its 

 tusks the trunk of the tree, up and down and all round, till it is 

 sufficiently weakened to be broken down. 



The beds including the above fossil remains stand only from 

 fifteen to twenty feet above the level of high water ; and hence 



1 Principles of Geology, vol. iv. p. 40. 



^ This theory was first developed in the Zoology of the Voyage of the Beagle^ and 

 subsecjuently in Professor Owen's Memoir on Mylodon I'obttstns. 



