origin of muscles, concerned in the movements of the foot. The radius (m) revolves freely on the ulna, as in the Sloths and Ant-eaters, both of which make much use of the fore leg, though for different purposes; it has a cavity at its upper end, which turns upon a spherical portion of the lower part of the humerus, and a large apophysis (n,) projecting from its longitudinal crest, indicates great power in the muscles that gave rotatory motion.
The entire fore-foot must have been about a yard in length, and more than twelve inches wide; forming a most efficient instrument for moving the earth, from that depth within which succulent roots are usually most abundant. This great length of the fore-foot, when resting upon the ground, though unfavourable to progressive motion, must have enabled one fore-leg, when acting in conjunction with the two hind legs and tail, to support the entire weight of the body; leaving the other fore-leg at liberty to be employed exclusively in the operation of digging food.[1]
The toes of the fore-foot are terminated by large and powerful claws of great length; the bones, supporting these claws, are composed partly of an axis, or pointed core, (o,) which filled the internal cavity of the horny claw; and partly of a bony sheath, that formed a strong case to receive and support its base. These claws were set obliquely to the ground, like the digging claws of the Mole, a position which made them instruments of greater power for the purpose of excavation.
- ↑ At Pl. 5, beneath Fig. 1, are represented the fore-foot of an Armadillo (Daspyus Peba), and the fore-foot of the Chlamyphorus, each adapted, like that of the Megatherium, to form an instrument of peculiar power for the purpose of digging; and each presenting an extraordinary enlargement and elongation of the extreme bones of the toes, for the support of long and massive claws. At Pl. 5, Figs. 18, 19, the anterior parts of these animals are represented, and show how large a proportion the claws bear to the other parts of the body.
