They are nocturnal in their habits, passing the day sleeping in the recesses of their burrows, and coming forth in the twilight one by one, until a large and lively company is to be seen playing about the neighbourhood of their holes. When all is quiet they go in search of their food, which consists of grasses and other herbage and roots, and sometimes of the bark of trees and shrubs. In cultivated fields they may do considerable damage. While engaged in feeding, one or other of the party is perpetually on the watch, and the moment anything occurs to cause alarm, the whole of them scamper away with their tails elevated, to take refuge in their holes. In their movements they are very like Rabbits, but less active. The Viscacha has the very singular habit of dragging all sorts of hard objects to the mouth of its burrow, where bones, stones, thistle-stalks, hard lumps of earth, dry cow-dung, and other chance articles may be found collected into a heap, frequently, according to Mr. Darwin, amounting to as much as a wheelbarrow would contain. Mr. Darwin says that he was informed that “a gentleman riding on a dark night dropped his watch; he returned in the morning, and by searching in the neighbourhood of every Viscacha hole on the line of road, as he expected, soon found it.” The purpose of this accumulation of apparently useless articles by the Viscacha has never been ascertained. It has been compared to the habit of some of the Australian Bower-birds, which adorn their playing-places with bright and glittering objects. [Illustration: VISCACHAS.] The Chinchillas of the Andes, or Alpine Chinchillas, are much lighter and more elegant animals than their cousins of the plains; in form they more resemble Squirrels or large Dormice. Their fur is excessively soft, perhaps the softest that clothes any animal, and in all the species it is of a grey colour, mottled or clouded with darker and lighter tints. The ears are of large size. They are confined to the Andes of Chili, Bolivia, and Peru, where they live among the bare rocks at a considerable elevation, seeking refuge in natural clefts and cavities, sleeping in their holes during the day, and coming forth at twilight in search of food. They are exceedingly lively and active in their movements, and very shy. [Illustration: MOLAR TEETH TEETH OF THE CHINCHILLA.]