126 The American Geologist. Feb. i89i 
6. The Bradypodidoe or Sloths. 
7. The Megatheriidse or Megatherians (extinct). 
The first five of these require no further notice here, not being 
sufficiently cognate with the subject. There remain only, there- 
fore, for consideration one living and one extinct famity. 
The tree-sloths, to which of all existing species Megalonyx is 
most closely allied, are among the most singular of living mam- 
mals. They have been pitied by naturalists on account of their 
supposed faulty structure, but very unnecessarily. Buffon sup- 
posed that its " existence must be a burden to the sloth. " Cuvier 
fell into the same error. "Nature seems," he sa3'S, "to have 
amused herself in producing something imperfect and grotesque 
with disproportioned structure and inconvenient organization." 
But these mistakes arose from seeing the animal out of its natural 
surroundings. The sloth whose sluggish movements on the 
ground, where it can neither walk nor stand but drags itself 
along, obtained for it its name, is constructed for living in the 
trees, not on or among the branches as monkeys, but under them, 
and for this life its structure is admirably adapted. Its long 
fore-legs, enormous pelvis and in-turning wrists and ankles compel 
it when on foot to walk or crawl on the outer edges of its feet 
and on the outer knuckles of its hands with the claws bent inward 
and upward as a man on all fours might crawl resting on the 
knuckles of the little fingers with fists doubled up and on the outer 
edges of his foot — a position as awkward to him as natural to the 
sloth. But put the creature into a tree and let it hang from a 
limb and it is b}' no means a sloth. It can climb with fair speed 
though its usual pace is slow, and in the tangled South American 
forests can pass for miles from tree to tree without descending to 
the ground. Clinging by the long hind claws and by one fore-foot 
with the other it draws together the branches and foliage on 
which it feeds. In this position it is free from fatigue, as is the 
horse when standing. During sleep it rests in the fork of a tree 
rolled almost into a circle and clasps the trunk with its fore-legs, 
protected to a large extent by the color of its hair which resem- 
bles dry grass or moss. Mr. Waterhouse even asserts that it fre- 
quently sleeps suspended. 
Its powerful claws are formidable weapons of defence. In 
danger the sloth throws itself on its back and seizing its enemy 
