While the Octodontinæ may be regarded as specially characteristic of the region of the Andes, the other great group of this family is almost exclusively confined to the country east of that great chain, and to some of the West Indian islands. Curiously enough this sub-family also has a single representative in Africa. Its members are distinguished at once by the complicated enamel folds of their molar teeth in both jaws, by these teeth being generally rooted, and by the texture of the fur, which is harsh and frequently mixed with fine spines. Hence the name of Echinomys (Spiny, or rather Hedgehog, Rat), applied to the typical genus, from which the sub-family is named ECHINOMYINÆ. The tail in these animals is usually long.
The Rodents belonging to this sub-family are generally of considerable size, as large as Rats, or larger, stoutly built, with the hinder part of the body larger than the fore-quarters, with limbs of moderate length, the hinder larger than the anterior, the former furnished with five toes, the latter with four complete digits and a rudimentary thumb, and the toes armed with strong curved claws. The tail is scaly, with scattered hairs. In their habits these animals appear to be strictly vegetable-feeders, but in other respects they present some variety. The majority live in and upon the ground; but one or two are arboreal, and one aquatic, in their mode of life.
The last species alluded to is the well-known COYPU (Myopotamus Coypus), one of the largest of Rodents, which occurs in nearly all parts of South America and on both sides of the Andes, from the tropic of Capricorn to about 15° N. lat. It is usually about twenty inches long, but often attains still greater dimensions. The tail, which is about two-thirds the length of the head and body, is scaly, with hairs about as thickly scattered as in the common Rat. The ears are of moderate size; the incisor teeth very large and powerful; the molars, the hindmost of which are the largest, have two internal and two external enamel-folds in the upper, and three internal folds and one external in the lower, jaw; the hind feet are webbed. The general colour of the upper surface is brown, produced by dusky and brownish-yellow pencilling; the sides and under parts are brownish-yellow, and the front of the muzzle and the chin white.
COYPU.
The Coypus live upon the shores of the rivers and lakes of South America, generally, according to Rengger, in pairs, each pair digging for themselves a burrow in the bank, which extends to a depth of three or four feet, and widens out into a cavity eighteen inches or two feet in diameter. Here they pass the night, and take refuge when necessary during the day. They select for their dwelling-places the stiller parts of the water, where the aquatic plants on which they chiefly feed grow freely. They are said to swim well, but not to be expert in diving. On land they are slow and awkward in their movements. They feed chiefly on the roots of plants, but in the Chonos Archipelago, where the Coypus frequent the sea and make their burrows at some little distance from the beach, they are said occasionally to eat shell-fish. The female produces from four to five young once in the year. The little animals very early accompany their mother into the water, when she swims with them on her back, until they have acquired the art of swimming. Mr. Waterhouse thinks that this habit may “explain the singular position of the nipples noticed in the female Coypu. Of these four were found by Mr. Lereboullet on each side of the body, and situated rather above the mesial line of the flanks, the foremost being placed behind the shoulder, and the hindermost in front of the thigh.” The Coypu is hunted for the sake of its flesh, which is described as white and of good flavour, and of its skin, which is well known in the fur trade under the name of “Nutria,” signifying Otter. Great quantities of these skins are annually exported from Buenos Ayres. It is said to be a courageous animal, fighting bravely with the dogs engaged in chasing it.
HUTIA CONGA.
TEETH OF PLAGIODON.