" If," says M. Cu vier, "we consider the Sloths in the relation which they bear to other ani mals, the general laws of organisation at present existing apply so little to their structure, the different parts of their body seem so completely contradictory of those laws of co-existence which we have found established in the rest of the animal kingdom, that we might be almost tempted to consider them as the remains of a former order of things, the living relies of that precedent nature of which we are obliged to seek the other ruins beneath the surface of the earth, and that they escaped by some miracle the catastrophe which destroyed their contemporary species." rarely voluntarily descends to the surface of the earth, and those therefore who observe it in that situation, have not a favourable opportunity of judging of its nature and functions.
We are indebted to the valuable observations of Mr. Waterton, during his c Wanderings' in South America, for a final and satis factory explanation of the apparent difficulties and inconsistencies in the structure and habits of the Sloth. " The sloth," says this traveller, "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 ; mid in lieu of the sloth leading a painful life and entailing a melan choly existence upon its progeny, it is hut fair to conclude that it just enjoys life 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." Nor are the motions of this animal so slow while suspended in this strange position, nor his habitat so circumscribed as naturalists have hitherto imagined. "The Indians," continues Mr. Waterton, "have a saying that when the wind blows the sloths begin to travel. In fact during calm weather they remain tranquil, probably not liking to cling to the brittle extremities of the branches, lest they should break whilst the animals are passing from one tree to another ; but as soon as the wind rises tho branches of the neighbouring trees become interwoven, and then the sloth seizes hold of them and pursues his journey in safety. He travels at a good round pace, and were you to see him, as I have done, passing from tree to tree, you would never think of calling him a sloth." Stedman, in his History of Surinam,' has an engraving of a Sloth in this position, which we have copied, as illus trating its singular mode of progression. A specimen of Chalcepus
didactylus, the Two-Toed Sloth, is now living in the Gardens of the Zoological Society, Regent's Park.
The conformation of the extremities is not the only part of its anatomy in which the Sloth differs from ordinary mammals. The number and form of the bones which compose the trunk, the nature of its teeth, and the conformation of its stomach and intestines, are all peculiar. The stomach is divided by transverse ligatures into four separate compartments, which bear a distant resemblance to the four stomachs of ruminating animals : they do not however exorcise the functions of these organs, nor do the Sloths regurgitate their food, or subject it to a second process of mastication like the ox and the sheep. The intestines also are unusually short for an animal which lives entirely upon vegetable substances, scarcely equalling twice the length of the body, whilst these of ruminants frequently exceed ten times those dimensions. Their simplicity and diminutive size in the Sloths appear to be compensated by the superior and unusual com plication of the atomach,—which, retaining the food for a longer period than in ordinary non-ruminating animals, allows it to be more perfectly macerated, and prepared for the action of the absorbent vessels which imbibe its nutritious particles in its passage through the intestines. The number of vertebrre in the necks of mammals is generally seven, so that the whales and dolphins, which have scarcely any neck at all, as well as the giraffe and camel, which have it developed in a most unusual degree, are all found to agree in this particular, however widely they differ in other respects : the B.' tridaetylue alone forms an exception to this otherwise universal rule, in having nine cervical vertebrae. What renders this circumstance still more surprising is, that the neck of the Sloth (B. tridact !due), notwithstanding its two supernumerary vertebra, is far from long— being on the contrary much too short for its long fore legs if it were compelled to seek its food on the ground like other animals. But this defect is compensated, as well by the nature of the situation which it habitually occupies, suspended from the horizontal branches of the trees, as by its power of using the fore paw as a hand in conveying the food to its mouth, which, notwithstanding the rigidity of its members, it does with great address with one paw, whilst it clings firmly to the branches by means of the other three.