These animals are of considerable size, usually measuring from sixteen to twenty inches in length without the tail, which is about one-third the length of the head and body. By the aid of the prehensile tip of this organ they climb with great facility and security upon the branches of the trees, but their feet are also specially adapted for this particular mode of activity, and they are said even to climb the palm-trees in order to feed upon their fruit. They are nocturnal in their habits, passing the day in sleep concealed in the fork of a branch, and going abroad at night in search of their food, which consists of fruits of various kinds, and the buds, leaves, and even flowers, of the trees on which they live. Roots also form a part of their nourishment, probably when they reside rather among thickets than in the high forest. Their spines, although short when compared with those of the Common Porcupine, are formidable defensive weapons when the animal erects them; in some species, as especially in the Couiy, they are concealed, when depressed, by the long hair, and, according to Hensel, this serves as a protection to the animal from rapacious birds, for, when it sits in a heap, sleeping away the daylight, these soft grey hairs give it a most deceptive resemblance to a mass of the beard-moss which so commonly grows on the trees in the Brazilian forests.
TREE PORCUPINE.
The URSON, or CANADA PORCUPINE (Erythizon dorsatus), the only North American species of the family, according to Mr. Allen, although other writers distinguish two or three such forms, is about two feet or more in length when full grown, and is covered with woolly hair, and with long coarse hair of a dark brown colour, with the points white or yellowish, this difference in the colour of the tips of the hairs being the chief distinction between the two varieties which Mr. Allen recognises. The spines in both forms are white, with the points usually dusky or brown. The Canada Porcupine is distributed through the whole of the Eastern United States, except on the seaboard, from New York to Virginia, and north of the States through Canada, as far as the limit of trees. The Western Porcupine, which has the tips of the long hairs yellowish (whence it has received the name E. epixanthus), occurs west of the Missouri river, extending to the Pacific shores and going southward along the mountains to Arizona and New Mexico, and northwards at least as far as Alaska and Sitka.
MEXICAN TREE PORCUPINES.
Although a heavy and clumsy-looking beast, and destitute of the prehensile tail of its South American cousins, this Porcupine is a good climber, and passes nearly the whole of its life upon trees; nevertheless, according to Mr. Allen, it may be met with travelling upon the prairies, probably on its way from one suitable residence to another. On the ground it moves slowly, but its armature of spines is a protection against most of its enemies, and it has the art of striking very forcible and judicious blows with its spiny tail. Audubon and Bachmann mention many cases in which Dogs, Wolves, and even a Puma were found dead or dying in consequence of the severe inflammation caused by the spines of this animal sticking about their mouths; and the former gives an interesting account of a lesson in urbanity given by a captive Urson to a Mastiff that attacked him. The food of the Urson consists of various vegetable substances, fruits, buds, and the young shoots and leaves of trees. In the winter it subsists chiefly upon the bark, which it strips off the upper branches of the trees, and when it has taken up its abode upon a tree it stays there until the suitable bark has been consumed. As it prefers young trees this operation is generally effected pretty quickly, and in this way it is estimated that a single Porcupine may destroy hundreds of trees in the course of a winter. The Urson resides in the holes of trees, and in such situations, or in crevices among the rocks, the female prepares her nest, in which she brings forth usually two, but occasionally three or four, young in April or May.
FAMILY XIII.—CHINCHILLIDÆ (THE CHINCHILLAS).
In the Chinchillas, which form a small family peculiar to South America, the incisor teeth are short; the molars are rootless, divided by continuous folds of enamel into transverse plates, and the two series in each jaw converge towards the front; the zygomatic arch has no angular process on the lower margin; the clavicles are slender but perfect; the fore limbs are small, the hind limbs long; the tail of moderate length or long, and turned up at the end; and the fur is very fine and soft. They are Rodents of moderate size and more or less of Rabbit-like appearance, except that the tail is always elongated and bushy. Of the five known species, four are inhabitants of the mountain regions, and one lives in the plains of the region of La Plata.
The latter, the VISCACHA (Lagostomus trichodactylus), is a stout-built and almost Marmot-like creature, from eighteen inches to two feet long, exclusive of the tail, which measures from six to eight inches. It has four toes on the fore limbs, and three on the hind feet, the latter furnished with long, compressed, and pointed nails; the muffle is broad and covered with a velvet-like coat of brown hair; the fur, which is soft and moderately long, is of a mottled grey colour above, and white or yellowish-white beneath; on each cheek there is a dark band; a white band crosses the muzzle and runs back on each side almost as far as the eye; the tail is dusky-brown or black.