Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/127

 Rh 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.

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.