THE RESTLESS CAVY. 143 



the structure of the limbs and of some other parts of the skeleton. Professor Peters is evidently 

 inclined to regard it as most nearly related to the Chinchillidfe. but as constituting a group establishing 

 a closer union than previously existed between the families Chinchillidee, Octodontidse, Dasyproctidse, 

 and Caviidse. 



FAMILY XVL CAVIID.E (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 RESTLESS CAVY (Cavia aperea), which is commonly regarded as the wild original of the so- 

 called Guinea-pig (Cavia cobaya of 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 dis- 

 tinguished 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 

 whei'e it occurs. According to Mr. Darwin, it is very common about the banks of the La Plata, some- 

 times 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 

 pi-esence 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 state- 

 ment 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 discoveiy 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 no 



