THIS animal, which is sometimes also called the Ai, in reference to a noise it makes when caught, and frequently when moving through the forest, is most curiously formed. The arms or fore legs are nearly twice as long as the hind legs: the claws also are larger than the foot, and bent inwardly, so as to prevent the animal from placing the ball of its foot on the ground. From these peculiarities in its construction the progress of the Sloth on land is extremely slow and laborious, for being incapable of supporting himself on his feet, he is compelled to take advantage of every little inequality in the ground to drag himself along; but he is not intended to be a terrestrial animal. He lives in trees, always hanging below the branch, with its back to the ground; and for a life of this kind, its long arms and hooked claws are admirably adapted. Mr. Waterton, whose long residence in the wilds of South America, and whose habits of close observation, render him an excellent authority, observes, that when the Sloth travels from branch to branch of the tree which it inhabits, particularly in windy weather, it moves with such rapidity as to make it quite a misnomer to call it a Sloth. “The Sloth,” says Mr. Waterton, “in its wild state, spends its whole life in the trees, and never leaves them, but through force or accident; and what is more extraordinary, not _upon_ the branches, like the squirrel and monkey, _but under them_. He moves suspended from the branch, he rests suspended from the branch, and he sleeps suspended from the branch. Hence his seemingly bungled composition is at once accounted for; and in lieu of the Sloth leading a painful life, and entailing a melancholy existence upon its progeny, it is but fair to conclude, that it enjoys life just as much as any other animal, and that its extraordinary formation and singular habits are but further proofs to engage us to admire the wonderful works of Omnipotence.” The common Sloth has always three toes; but there is another kind, called the Unau, which has only two toes, and much shorter fore legs.