Chapter 31

SECTION III.—PORCUPINE-LIKE RODENTS (HYSTRICOMORPHA).

FAMILY XI.—OCTODONTIDÆ.

This first family of the Porcupine alliance consists of a number of rat-like animals, nearly all of which are inhabitants of South America, three species only being peculiar to the large West Indian Islands, whilst, singularly enough, four more are known from different parts of the African continent. Except in one of these last, all the members of the family have four molars on each side in each jaw, and the crowns of these teeth show internal and external folds of enamel. The malar portion of the zygomatic arch has an angular process at its lower margin.The hind limbs are not disproportionately developed, and both they and the fore feet are nearly always furnished with five toes, armed with curved claws; and the clavicles are perfect. The ears are generally short and sparingly hairy, and the tail, which is of various lengths, is either clad with short hairs, or naked and scaly.

We may begin with two African species of this generally American family, which have the two inner claws of the hind feet furnished with comb-like fringes of horny bristles, whence the name ofCtenodactylushas been applied to the best known species. These two species, which exhibit strong affinities to the Jerboas, form the sub-family CTENODACTYLINÆ. The GUNDI(Ctenodactylus Massoni) has only three molars on each side in each jaw, and only four toes upon each foot. It is an animal about the size of the Water Rat, but with a mere stump of a tail, very small ears, very long whiskers, and the hind limbs rather longer than their fellows. It lives in North Africa, chiefly on the borders of the Sahara, where it takes up its abode in the rocky hills, and descends therefrom to the cultivated grounds to feast upon the growing corn. It is diurnal in its habits, but exceedingly shy and watchful, making off to its fastnesses at the least appearance of danger.Pectinator Spekei, a species named after its discoverer, the celebrated African traveller, is nearly related to the preceding, but has a small additional molar in each series. The tail is of moderate length, and bushy, and the ears have a small antitragus. It inhabits the Somali land in the interior of North-eastern Africa.

DEGU.

The DEGU(Octodon Cumingii), a very abundant species in Chili, which also extends into Peru, may be taken as a typical example of the whole family, and also of its typical sub-family OCTODONTINÆ, in which the molars are simply indented on each side. The fur is soft, and the tail is short. The Degu is a rat-like animal, rather smaller than the Water Vole, the head and body measuring from seven and a half to eight inches in length, and the tail, exclusive of its terminal tuft, rather more than half that length. The general colour of the animal is brownish-yellow, pencilled with black on the back; the lower surface is yellowish, the feet white, and the tail dusky above, whitish beneath, with the tufted tip dusky or blackish. In the central parts of Chili, according to various travellers, the Degu is exceedingly abundant, living in large societies about hedges and thickets, and running about boldly, even on the high roads. The animals make their burrows in the hedge-banks and similar places, and when alarmed rush into them with their tails elevated, very much after the manner of Rabbits. As the burrows communicate freely with each other, the Degus can easily escape pursuit, going in at one opening and coming out at another at some considerable distance. They sometimes climb up into the bushes among which they live. Their ordinary food consists of the herbage which grows about their dwelling-places, but they also invade gardens and fields, where they may do considerable damage. In the winter they will feed upon the tender bark of certain trees, but they are said by some authors to lay up a store of food against this season. They do not become torpid. The female is believed to produce two broods in the year, each consisting of from four to six young. Two other species ofOctodonare known from Chili and Bolivia, which region is also inhabited by two species ofHabrocoma, a genus distinguished by the large size of the ears, and the extreme softness of the fur. In these animals the molar teeth differ in the two jaws, the upper ones being as simple as in the preceding species, while the lower ones show a complication of the enamel folds like what we shall meet with in the third sub-family.

The BROWNSCHIZODON(Schizodon fuscus), which inhabits certain elevated spots in the southern part of the Andes (75° S. lat.), has the enamel folds of the molar teeth meeting in the middle. It is about the size of the common Rat (seven and a half to nine inches long), and has a shortish tail clothed throughout with short hairs. Its fur is dark brown above, dirty yellowish beneath. This animal inhabits grassy places near mountain streams, where the ground is sometimes so undermined by its burrows as to render travelling on horseback very uncomfortable. It is a nocturnal animal, and passes most of its life underground. The valleys it inhabits are covered with snow for at least four months in the year.

In the TUKOTUKO(Ctenomys brasiliensis) and its congeners, about four of which are known from different parts of South America, one of them extending as far south as the Strait of Magellan, the eyes and ears are very small, and the animal seems to be still more specially adapted to a subterranean mode of life. In these animals the claws are longer than the toes, and those of the hind feet are fringed with a sort of comb formed of bristles. The incisor teeth are very broad. The Tukotuko is about the size of a large Rat, namely, from eight and a half to nine and a half inches long, with the tail from two and a half to three and a half inches. Its name is in imitation of the sound which it constantly emits—a sound which rather surprises a stranger when he first hears it, seeing that the animal uttering it is concealed underground. In many places, as in the Argentine Republic, this animal is exceedingly numerous, living generally in sandy soil, but sometimes in damp situations. It makes long burrows not far from the surface, and thus in some places completely undermines the ground. In making these galleries the Tukotuko is engaged in the search for its food, which consists chiefly of the roots of plants. According to Azara, it lays up stores of food in its burrows. Its activity is nocturnal.

The CURURO(Spalacopus Pöppigii) has the ears quite rudimentary, and is also organised for a subterranean existence. This and another species inhabit Chili, where they make extensive burrows in the ground, and feed upon the bulbous and tuberous roots of various plants, large stores of which they collect in their subterranean abodes. These magazines are sought out by the poorer people, and their contents used as food.

DENTITION OF THE ROCK RAT.

The ROCKRAT(Petromys typicus), although most nearly allied to the preceding species, lives on the opposite side of the Atlantic in the rocky hills of South Africa, especially towards the mouth of the Orange River. It differs from the preceding forms in the harshness of its fur, in which it resembles another sub-family of Octodontidæ, in the shortness of its thumbs, which are furnished with a small nail, and in its rather bushy tail. The molars are semi-rooted, with the enamel folds nearly meeting in the middle. The whiskers are of great length, and entirely black. The general colour is reddish-brown, with the head and fore parts greyish, the throat whitish, and the belly pale yellow. The tail is of the colour of the body at the root, with the remainder black. The length of the animal is about seven and a half inches, of the tail from five to five and a half inches. It feeds upon various vegetable substances, and appears to be very fond of the flowers of syngenesious plants, especially a species of groundsel, which it eagerly devours. It forms its retreat among loose stones, or in crevices of the rocks.

TEETH OF THE SPINY RAT.

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 singlerepresentative 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 ofEchinomys(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 saidoccasionally 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.

MOLAR TEETH OF LONCHERES.

The HUTIACONGA(Capromys pilorides) is another large Rodent, measuring from twenty to twenty-two inches in length, with a stout rat-like tail about half as long as the head and body. It is an inhabitant of Cuba. The incisors are considerably smaller and weaker than in the Coypu; the upper molars have one internal and two external folds; the lower ones are similar but reversed. The fur, which is long, is very harsh, and consists of a mixture of black and yellow hairs, becoming rusty on the hinder part of the body. The belly is rusty yellow. This animal lives in the denseforests of Cuba, where it resides either upon the trees or in the thick underwood. It is a nocturnal or crepuscular animal, and is tolerably active when going about on the branches of trees, but is less at home on the ground. Its food consists of fruits, leaves, and the bark of trees, but, according to M. Ramon de la Sagra, it does not disdain animal food, and is especially fond of a species of Lizard belonging to the genusAnolis. On the other hand, the negroes are very partial to the flesh of the Hutia, and they capture the animal either by snaring it on the branches of trees, or by sending Dogs after it. Like the Coypu, it is said to fight courageously against its pursuers. Another Cuban species, the HUTIACARABALI(C. prehensilis), has a slightly longer tail, which is prehensile at the tip. It is described as keeping chiefly to the highest branches of the trees. In St. Domingo there is an allied form,Plagiodon ædium, in which the enamel folds of the molars are singularly complex (seefigure on p. 132). This animal frequents the neighbourhood of human habitations, and approaches them at night in search of its food, which consists of fruit and roots. In most of the other members of this sub-family, which appear to be terrestrial in their habits, the intermixture of spines with the fur of the back is a striking character. In the genusEchinomysitself, and inLoncheres, which together include about a dozen species found chiefly in Guiana and Brazil, the spines frequently form the principal outer covering of the back. Side by side with these hedgehog-like species, however, others occur in which the fur is soft.

SKULL OF LONCHERES.

The GROUNDRAT(Aulacodus Swinderianus), of Western and Southern Africa, is remarkable as being the sole representative of this group outside the South American province. It has very broad incisors, and those of the upper jaw exhibit three deep grooves; the molars show the same arrangement of folds as inCapromys; the fur is harsh and bristly, and of a general brown tint; and the tail is of moderate length, sparingly haired, dusky above, and whitish below. The fore feet have the thumb rudimentary and the outer toe very short; and the hind feet have only four toes, of which the outer one is rudimentary. This curious animal, which is nearly two feet long, is known to be an inhabitant of Sierra Leone and the Gambia, and also of South Africa (Port Natal); in all probability it occurs at many intermediate localities. In Sierra Leone it is known as the Ground Rat, or Ground Pig, and is said to feed upon ground nuts, and cassada and other roots in search of which it digs into the ground, where it also forms large burrows for its residence.

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