The South American Forests--Discovery of the Sloth--How it derived its Name--Peculiarities of Dentition--Food--Fore Limbs and Fingers--Hind Limbs and Heel--Other Modifications of Structure--Kinds of Sloth--Waterton’s Captive Sloth--Habits of the Animal--Burchell’s Tame Sloths--Manner of Climbing Trees--Disposition--Activity among Trees--Naturalists’ Debate about Anatomy--Probable Conclusion regarding it--Skeleton--Vertebræ--the Rudimentary Tail--Most Distinctive Skeletal Characters--Arm, Wrist, Hand, Fingers, Claws--Mode of Walking--Great Utility of the Claws--Face of Sloth--Skull--Teeth--Classification--_TARDIGRADA_--BRADIPODIDÆ--Genus BRADYPUS--Characteristics--Genus ARCTOPITHECUS--Characteristics--CHOLŒPODIDÆ--THE COLLARED SLOTH--Description--Skull Bones--Habits--Circulation of the Blood--_Rete Mirabile_--THE AI--THE UNAU--Appearance--Skull and Teeth--Skeleton--Interesting Anatomical Features--Stomach--HOFFMANN’S SLOTH--Description--Habits. When the dense forests of the northern parts of South America were first explored by Europeans, it was observed that active Spider Monkeys, Howlers, and their Quadrumanous allies, were not the only climbing animals which frequented the trees. For every now and then, hunters came in sight of creatures about the size of a large Monkey, but whose sluggish movements, long hair, short heads, small ears and tail, and very long claws, enabled them to be distinguished at once from their very lively companions. It was noticed that these new creatures, instead of climbing quickly and swinging from branch to branch and running along the boughs, moved very slowly, by hanging head and body downwards and grasping the branches with their long claws. During the daytime, these quiet animals were constantly found asleep, huddled up in the fork of a branch, and looking like great balls of tow, or else hanging by two legs, the rest of the body being curled up. Now and then, one was seen at the foot of a tree, and it appeared to run along the ground with great difficulty; for the arms were so long that it walked on the elbows, and the hind feet were turned in, so that it supported itself on the sides of its great hind claws. Naturally, the animal took its time in moving, and as it was never seen to be lively, it received the name of Sloth. Interesting from being so different in its habits from other arboreal animals, it became much more so, to naturalists, when its remarkable construction was ascertained; but still the hairy creature with a short face, small head, long neck, hardly any tail, and very long front limbs, retained its popular name.