The Sloth, in its wild condition, spends its whole life on the trees, and never leaves them but through force or accident; and, what is more extraordinary, it lives not _upon_ the branches, like the squirrel and the monkey, but _under_ them. Suspended from the branches, it moves, and rests, and sleeps. So much of its anatomical structure as illustrates this peculiarity it is necessary to state. The arm and fore-arm of the sloth, taken together, are nearly twice the length of the hind legs; and they are, both by their form and the manner in which they are joined to the body, quite incapacitated from acting in a perpendicular direction, or in supporting it upon the earth, as the bodies of other quadrupeds are supported by their legs. Hence, if the animal be placed on the floor, its belly touches the ground. The wrist and ankle are joined to the fore-arm and leg in an oblique direction; so that the palm or sole, instead of being directed downwards towards the surface of the ground, as in other animals, is turned inward towards the body, in such a manner that it is impossible for the sloth to place the sole of its foot flat down upon a level surface. It is compelled, under such circumstances, to rest upon the external edge of the foot. This, joined to other peculiarities in the formation, render it impossible for sloths to walk after the manner of ordinary quadrupeds; and it is indeed only on broken ground, when he can lay hold of stones, roots of grass, &c., that he can get along at all. He then extends his arms in all directions in search of something to lay hold of; and when he has succeeded, he pulls himself forward, and is then enabled to trail himself along in the exceedingly awkward and tardy manner which has procured for him his name.