date of its introduction is unknown.-The Lagomys or Pica of Siberia, an animal nearly allied to the Hare, is of much interest, on account of its peculiar instincts. It is about the size of a Guinea-pig, and lives on the sides of mountains, concealed in hollows in the rocks, or inhabiting burrows which it has itself excavated. In the autumn it selects and dries herbage for its winter provision; and of this it makes regular stacks, which are sometimes four or five feet in height, by eight in breadth. A subterranean gallery leads from the burrow to the stack; so that neither frost nor snow can intercept the communication with it. The herbage is most carefully selected, and consists chiefly of the choicest grass and the sweetest herbs, all cut when most vigorous, and dried so slowly as to form a green and succulent fodder; and the collections of it furnish a valuable supply of food for the horses of the Sable-Hunters. The Picas are also remarkable for their voice; the tone of which so much resembles that of a quail, as to be often mistaken for it, even by the inhabitants of their native districts. Their peculiar loud and sonorous note or call is heard only in the morning and evening (except in dark and cloudy weather), and is repeated by each animal, both male and female, at regular intervals.

238. The Fossil animals belonging to this order are mostly found in very recent strata, and generally bear a very close resemblance to those already existing. Some of them, however, were of much larger size; especially those inhabiting South America. Thus the remains of a species of Capybara has been found there, which must have been nearly five feet in length; so as to stand midway between the existing species, and the South American Tapir. Remains of an Agouti, also, have been discovered, of such a size that the long bones of its hind legs were nearly as large as those of a Roebuck. And of the Coendou (or prehensile-tailed Porcupine), a species must have formerly existed, very little inferior to the wild Hog in bulk. Vast numbers of remains of various Rodents allied to the existing species, are found in a fossil state in the caves of that country; and great heaps of bones of the smaller animals of this group at present existing there, are met with in the soil of other caves, in such a

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state as to lead to the belief, that they were brought together by Owls. Remains of Mice and Water-Rats have been found in the Kirkdale Cave in Yorkshire.

ORDER VIII.-EDENTATA.

239. This order contains a number of animals, recent and fossil, which differ from each other most widely in habits, and in those points of their structure which especially adapt them to those habits; and which yet agree in so many essential characters, and are connected together by so many intermediate links, as evidently to require being associated in the same group. The leaf-eating, tree-inhabiting Sloths, at present existing in South America, the gigantic Mylodon and Megatherium, which formerly inhabited that Continent, and gained their subsistence, not by climbing the trees that afforded it, but by uprooting them with their immense digging feet,-the armour-clothed, insectivorous Armadillos, also inhabiting South America, the hairy, toothless Ant-Eaters of the same Continent,-and the scaly Pangolins of Southern Africa,-might almost be regarded as types of distinct groups, so widely do they differ from each other in external form and covering. The name given to the order is very liable to mislead; for it might be inferred from it, that the animals composing the group are altogether toothless, which is the case in regard to a small section of it only. They all agree, however, in the absence of teeth in the front of the jaws; and the molar teeth, in those which possess them, are comparatively imperfect in their structure, being destitute of enamel and of distinct roots. The Edentata constitute the last group of Unguiculated animals; and in the diminution of the number of toes which some of them present, as well as in the complete enclosure of these in a large hoof-like nail, there is an obvious tendency towards the ungulated structure, which is fully developed in the succeeding orders.-The existing species of this order may be subdivided into two principal groups, according to the nature of the food on which they respectively subsist; the first,

to which the name of TARDIGRADA has been given, on account of the slowness of the movements of the animals composing it, consists of the Leaf-eaters ;-and the second, which includes the Insect and Flesh-eaters, has received the name of EFFODIENTIA, on account of the digging habits which prevail in it. These names are not, however, by any means universally applicable; for there are digging animals in the first group; and slow-paced ones in the second.

240. The family TARDIGRADA, Contains but a single genus of animals now existing, the Bradypus or Sloth; an animal on which Naturalists have most liberally bestowed their pity. Not only did Buffon fall into the error of supposing it to be an imperfectly-constructed being, whose existence must be a burthen to it; but even Cuvier, whose views were in general much more sagacious, fell into the same mistake. In the construction of the Sloth, he remarks, "Nature seems to have amused herself in producing something imperfect and grotesque;" and he afterwards goes on to speak of their" disproportioned structure,” and the "inconveniency of their organisation." The fact is, as Dr. Buckland has well shown, that the organisation and habits of the Sloth are as completely adapted to each other, as are those of any other animal; and that our different notion respecting it is founded, on our usually seeing it only in an unnatural condition, for which it is not fitted. For the Sloth is formed to be produced, to live, and to die, not on the ground, but in trees; and not on the branches, like the Squirrel or Monkey, but under them; and when this is once fully understood, the complete adaptation of its whole structure to its mode of life becomes apparent.

241. The first peculiarity in the construction of the Sloth, which especially strikes the observer, when the animal is placed upon the ground, is the length of the fore-legs, which are twice as long as the hinder pair; and the very oblique connection of the hind-legs with the body, arising from the great breadth of the pelvis. The structure of the wrist and ankle-joints is such, that the palm or sole, instead of being directed towards the

* Linnæan Transactions, 1835.

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surface of the ground, is turned towards the body; so that the animal is obliged to rest upon the side of the hind-foot, and upon the elbow (not upon the extremity) of the fore-limb; and it can only advance itself, by a most awkward shuffling movement; or by laying hold, with its long crooked claws, of some fixed object, towards which it draws itself. But these peculiarities ought no more to excite our pity and compassion, than the circumstance of Fishes being deprived of legs, and unable to move upon dry ground; for when the Sloth is placed in its natural condition, they show themselves to be most perfectly adapted to its peculiar mode of existence, for which no other

animal is equally fitted. When placed in a tree, the Sloth is no longer the slow-moving, piteouslooking, animal which it is commonly reputed; for it climbs the trunk, and passes from branch to branch, with considerable rapidity, having been known to ascend, in a minute, from the bottom to the top of a lofty tree. The only three species of Sloth, at present known to exist,-the Ais, or three-toed Sloths, (of which there are two species, slightly differing from each other), and the Unau, or two-toed Sloth,-are inhabitants of the dense forests of the tropical portion of South America, the branches of whose trees are so intertangled with one another, that hundreds of miles may be traversed by passing from one tree to another. Clinging by the hinder claws, the posterior limbs securely embracing the bough, and generally holding by one of their forelimbs also, they employ the other to hook towards them the foliage on which they browze. Their long arms, with the firm claws by which they are terminated, enable them to pass from branch to branch, even when these are at some distance from each other; and when they live in the more open parts of the forest,

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where the trees are less contiguous, they take advantage of windy weather, which blows the boughs together, to effect their passage,

-seldom coming to the ground, and completely stripping the tree of its leaves and young shoots, rather than do so. From the peculiar construction of the Sloth, and the remarkable power of resisting tension, or strain, which its limbs seem to possess, it appears to feel no more fatigue from remaining suspended beneath a branch for a long time together, than we do from sitting or standing erect, a position which the Sloth could not maintain for an instant without support. The position which the Sloth assumes during sleep, is no less peculiar than that of its period of activity. It takes its place at the fork of a tree, the arms embracing the trunk, the back resting upon the angle of the branch, and the head reclining on the chest. The animal is thus rolled up almost in the form of a ball; the entire vertebral column, including the neck, assumes a nearly circular curve; and not only is the weight of the whole body maintained in an attitude of ease and safety, but the head is supported between the arms and chest, and the face