PREVIOUS TO THE LAST GEOLOGICAL REVOLUTION. 159 



may serve to elucidate the habits of that extraordinary tenant 

 of a foraier world, now under our consideration. Now, the 

 Megalonyx, like the sloth, is provided with powerful clavicles ; 

 like it also, its anterior extremities are longer than the hind; 

 its toes are armed with immense claws ; and lastly, the sole 

 of its hind foot is turned inwards instead of downwards. 



The first of these characters, or the existence of perfect 

 clavicles, proves that this animal used its fore- extremities 

 for more purposes than for walking ; which position I take 

 to be incontrovertible, as it is founded on a rule that has 

 no exception among mammals. The purposes for which 

 mammals, provided with clavicles, employ their anterior 

 extremities, are the following : — 1st, for flying, as in the 

 bats, with which we have nothing here to do ; 2dly, for the 

 apprehension of food, and the bringing it to the mouth, either 

 with one hand, as in the apes, or with two, like most rodents, 

 some marsupials, &c. Now, the first of these purposes re- 

 quires a peculiar disposition of the fingers, and a certain 

 freedom of motion in them ; which conditions are both 

 wanting in the Megalonyx, notwithstanding this animal, as 

 well as the Megatherium, has in reality been classed by 

 Wagler among apes. The second purpose is confined to ani- 

 mals that have short fore-limbs, and whose dental system is 

 adapted to gnaw substances which they hold in their paws ; 

 which conditions being also inapplicable to the Megalonyx, 

 there can be no occasion to dwell longer on them ; 3dly, for 

 tearing asunder their prey, as in the feline tribes. This pur- 

 pose requires only an imperfect development of the clavicles, 

 but at the same time, a peculiar arrangement in the shape and 

 attachment of the claws ; which, again, is not the case in the 

 Megalonyx. Besides, the dental system proves it to have 

 been graminivorous ; although authors have not been wanting 

 ( as Jefferson and Faujas) who have placed it among the 

 Carnivora. 



There remain, therefore, only two functions that are exer- 

 cised by the animals provided with bones for the attachment 

 of claws ; viz. digging and climbing. And it is the more 

 necessary to confine our attention to these two points, inas- 

 much as we see that all animals belonging to the same order 

 as Megalonyx, exercise one or the other of these functions. 

 Their immediate instruments for these purposes are claws, 

 which consequently are powerfully developed in all ; but in 

 none in so high degree as in the extinct genera Megalonyx 

 and Megatheriu7n : in these they have reached the highest 

 degree of development we yet know in the animal kingdom. 

 It would be contrary to all experience in natural history, to 



