FAMILY XVI.—CAVIIDÆ (CAVIES).
FAMILY XVI.—CAVIIDÆ (CAVIES).
This family, the last of the simple-toothed Rodents, includes a small number of species, of which the Common Guinea-pig may serve as a sort of type. The Guinea-pig is, however, one of the smaller species of the family, and is shorter in the limbs than most of its relatives. They have the incisor teeth short, that is to say, not extending far back in the jaw; the molars are rootless, variously divided by folds of enamel into lobes, the angles of which are acute; the palate is narrow in front, so that the upper series of molars approach each other rather closely in front; the clavicles are rudimentary or wanting; the fore limbs have four and the hind feet only three toes, all armed with hoof-like nails; the upper lip is not cleft; and the tail is rudimentary or wanting. They are stout, more or less rabbit-like animals, with a soft coat, and the ears variable in length; and they are confined to the continent of South America, where they chiefly inhabit the plains.
The RESTLESSCAVY(Cavia aperea), which is commonly regarded as the wild original of the so-called Guinea-pig (Cavia cobayaof some authors), is abundant on the banks of the Rio de la Plata, and extends thence northwards through Paraguay into Bolivia and Brazil. It is usually about nine inches long, with the fur of the upper part and sides of the body composed of a mixture of black and dingy yellow hairs, the chest greyish-brown, and the throat and belly pale dingy-yellow or brownish-grey. The incisor teeth are white. The genus to which this animal belongs may be at once distinguished from the other two genera constituting the family by the shortness of the limbs; the ears also are short; the feet are naked beneath; the hind toes are not webbed; and the molar teeth are nearly equal in size, and each composed of two angular lobes.
The specific name of the Restless Cavy seems to be derived from its popular name in the country where it occurs. According to Mr. Darwin, it is very common about the banks of the La Plata, sometimes frequenting sandy hillocks, and the hedge-rows formed of the agave and the prickly pear, but apparently preferring marshy places covered with aquatic plants. In dry places it makes a burrow; but when it frequents wet localities contents itself with the concealment afforded to it by the herbage. Rengger describes it also as generally haunting moist situations in Paraguay, and he adds that it keeps near the borders of forests, but is never found either in the forests or in the open fields. It lives in small societies of from six to fifteen individuals, in the impenetrable thickets of Bromelias, where its presence is revealed by the numerous beaten paths which it produces by going to and fro. In Bolivia, according to Mr. Bridges, it is peculiar to the low lands, and there takes shelter among the loose stones of the walls enclosing the fields. It is active in search of food early in the morning and in the evening, but will also come forth on gloomy days. Rengger and Azara both agree in the statement that the female produces only one or two young at a time; but the former says that this takes place only once in the year, whilst the latter describes the animal as breeding all the year round, and, indeed, in this way accounts for its abundance, notwithstanding its being preyed upon so extensively by rapacious birds and quadrupeds.
The question whether our common Guinea-pig is really the domesticated descendant of the animal just described can hardly be regarded as finally settled, and, indeed, independently of colour, there are sufficient differences between them to justify some doubt on the subject. The name Guinea-pig may, as Mr. Waterhouse suggests, be a mistake for Guiana-pig, and the first specimens may very probably have come from that part of America. Its prevalent colours, as is well known, are combinations of white, black, and yellow, and as these colours are shown in the drawings of Aldrovandus, dating back to within fifty years of the discovery of South America, there seems every reason to believe that the animal must have been long domesticated in America prior to its introduction into Europe. On the other hand, Dr. Rengger says that he saw fourteen Apereas representing the fifth or sixth generation from a single couple domesticated about seven years before, and that these exhibited nodifference of colouring from the wild animal. Several allied species inhabit the great plains of South America.
The BOLIVIANCAVY(Cavia boliviensis), which is grey in colour, with a faint yellowish tinge, with the throat and belly white, the feet whitish, and the incisor teeth orange yellow, inhabits the elevated parts of Bolivia, generally at a height of 10,000 or 12,000 feet. The ROCKCAVY(Cavia rupestris) is found in rocky districts in Brazil, where it shelters itself in holes and crevices. It is always found near the upper waters of rivers, and is a large species, measuring thirteen or fourteen inches in length. The SOUTHERNCAVY(Cavia australis), on the other hand, is a small species which inhabits Patagonia, where it ranges from 39° S. lat. to the Strait of Magellan.
This part of the world is also the abode of another and much larger species of the family, the PATAGONIANCAVYor MARA(Dolichotis patachonica), an animal which somewhat resembles the Agouti in the length and comparative slenderness of its legs, and differs from all other Cavies in having tolerably long, pointed ears. It also possesses a very short tail. The molar teeth are rather small, and resemble those of the Guinea-pig in being formed of two nearly equal angular lobes, but the last molar in the upper jaw, and the first in the lower jaw, have three such lobes. The animal is somewhat Hare-like in its appearance, and has been mistaken for a Hare by superficial observers. It is, however, a much larger animal, measuring from thirty to thirty-six inches in length, and weighing from twenty to thirty-six pounds.
PATAGONIAN CAVY.
PATAGONIAN CAVY.
The Patagonian Cavy is clothed with a dense crisp fur of a grey colour on the upper part of the head and body, rusty yellow on the flanks, and white on the chin, throat, and belly; the rump is black, with a broad white band crossing it immediately above the tail. It inhabits Patagonia about as far south as 48°, and extends northwards into the La Plata territory as far as Mendoza. It is found only in the sterile desert part of the country, where the gravelly plains are thinly covered with a few stunted thorny bushes and a scanty herbage. The northern limit of the species, according to Mr. Darwin, is at the point where the vegetation of the plains becomes rather more luxuriant. The Patagonian Cavy usually burrows in the ground, but where it lives in the same region as the Viscacha, it will take advantage of the excavations made by that animal. It wanders to considerable distances from its home, and on these excursions two or three are usually seen together. Mr. Darwin says:—“It is a common feature in the landscape of Patagonia to see in the distance two or three of these Cavies hopping one after the other over the gravelly plains.” Their mode of running, on the same authority, more nearly resembles that of the Rabbit than of the Hare; though their limbs are long, they do not run very fast. They rarely squat like a Hare, but are very shy and watchful, and feed by day, in connection with which it is to be observed that the eyes are defended from the direct rays of the sun by well-developed eyelashes, which do not occur in the other Cavies. The female produces generally two young at a birth, which are brought forth and suckled in the burrow.
The CAPYBARA(Hydrochœrus capybara), the only other member of the present family, is the largest of all existing Rodents, large specimens measuring over four feet in length. It is a stout-built and massive animal, with limbs of moderate length, a large head with a very blunt muzzle, smalleyes and ears, no tail, and both the fore and hind feet webbed. The upper incisor teeth have a broad and shallow groove down the front, and the molars present very remarkable characters. In the upper jaw the first three molars are each composed of two lobes united by cement, and on the outside of each of these lobes there is a fold of enamel which passes deeply into the tooth. The last molar consists of one lobe similar to those of the preceding teeth, but in place of the second there are ten or a dozen transverse plates. The first two molars of the lower jaw exhibit complex lobes and folds of enamel; the third and fourth a combination of folded lobes and transverse plates.
In its general form the Capybara is more pig-like than any of its relatives, and, indeed, its generic name,Hydrochœrus, Water-pig, recalls this resemblance, and at the same time intimates its aquatic habits. Its coat is composed of long and coarse hairs, often five or six inches long on the hinder parts, of a reddish-brown colour above, and a dirty brownish-yellow beneath. It is distributed over the whole eastern part of South America, from Guiana southwards to the Rio de la Plata, and ranges westwards into the lower parts of Peru and Bolivia.
MOLARS OF THE CAPYBARA.
MOLARS OF THE CAPYBARA.
The Capybaras frequent the borders of the lakes and rivers, with which all this part of the South American continent abounds, and, according to Mr. Darwin, they used to frequent the islands in the mouth of the La Plata, where the water is quite salt. In this part of America they are called “Carpinchos.” They never wander far from the water-side, and show a marked preference for the larger rivers, among the reeds and other plants fringing which they take up their abode. In populous districts they seem to pass the day in concealment, coming forth in search of food only at morning and evening, but where they are less in danger of pursuit they come out freely in the day-time. Seen from a little distance when walking they have much the appearance of Pigs, but they lose this when they sit, like the other Cavies, on their haunches. When danger threatens they emit a short, sharp bark, and immediately plunge into the water, where they swim about with little more than the nostrils above the surface; but under pressing circumstances they can dive and swim for a considerable distance under water. When swimming, the female is said to take her young ones on her back. About Maldonado Mr. Darwin observed that the Capybaras were usually to be seen only three or four together, but they are more numerous and go in larger companies more in the interior of the country. They constitute the ordinary food of the Jaguar, and are also eaten by the Indians, although their flesh is said not to be very good. The female produces five or six young at a birth, but has only one litter in the year. The young follow their mother about at a very early age.