92 EXTINCT ANIMALS. [chap. v. 



gravel and reddish mud, just such as the sea might now 

 wash up on a shallow bank. They were associated with 

 twenty-three species of shells, of which thirteen are recent 

 and four others very closely related to recent forms ; whether 

 the remaining ones are extinct or simply unknown, must 

 be doubtful, as few collections of shells have been made on 

 this coast. As, however, the recent species were embedded 

 in nearly the same proportional numbers with those now 

 living in the bay, I think there can be little doubt, that this 

 accumulation belongs to a very late tertiary period. From 

 the bones of the Scelidotherium, including even the knee- 

 cap, being entombed in their proper relative positions, and 

 from the osseous armour of the great armadillo-like animal 

 being so well preserved, together with the bones of one ot 

 Its legs, we may feel assured that these remains were fresh 

 and united by tneir ligaments, when deposited in the gravel 

 together with the shells. Hence we have good evidence that 

 the above enumerated gigantic quadrupeds, more different 

 from those of the present day than the oldest of the tertiary 

 quadrupeds of Europe, lived whilst the sea was peopled with 

 most of its present inhabitants ; and we have confirmed that 

 remarkable law so often insisted on by Mr. Lyell, namely, 

 that the " longevity of the species in 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 t lately 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 down- 

 wards on trees, and feeding on the leaves. It was a bold, 

 not to say preposterous, idea to conceive even antediluvian 

 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 



* " Principles of Geology," vol. iv., p. 40. 



t This theory was first developed in the " Zoology of the Voyage of the 

 BeaglCf" and subsequently in Professor Owen's " Memoir on Mylodon robustus." 



