182 RODENTS. 



selves. In from five to six months the young guinea-pig is able to reproduce its 

 kind, although it does not attain full maturity till eight or nine weeks. With 

 care, these animals will live for six or eight years. Although guinea-pigs seem too 

 stupid to display the slightest affection for their owners, they have the great 

 advantage of never making any attempts to bite, and may therefore be handled by 

 children with impunity. 



The Bolivian cavy (C. boliviensis), which is of rather smaller 



size than the restless cavy, is interesting from its habitat. It lives 



among the higher regions of the Bolivian Andes at elevations of from ten to 



twelve thousand feet; dwelling in large societies, and forming burrows which 



completely undermine the whole ground in certain districts. In colour this species 



has the fur of the upper-parts grey, with a yellowish tinge, while the throat and 



under-parts are white, and the feet whitish. The incisor teeth are orange in front. 



The last species of the genus that we shall notice is the rock- 



cavy (0. rupestris), differing from those mentioned above by the 



extreme shortness of its claws, which scarcely project beyond the toes. It has 



the fur greyish above, and whitish beneath. This species inhabits rocky districts in 



certain parts of Brazil, dwelling in cracks and crevices, and not constructing 



burrows. It is much hunted by the Indians, and it is known to them as the 



hoki. 



The Patagonian cavy, or mara (Dolichotis patachonicci), is readily 

 'distinguished from the true cavies by its longer limbs and ears, and 

 the presence of a short tail, which is always turned to one side. Its skull is 

 characterised by the extreme narrowness of the front portion of the palate ; this 

 being carried to such an extent that the premolar teeth of opposite sides are 

 actually in contact at their front edges. In length it is from 30 to 34 inches, and 

 it stands about 13 inches at the shoulder. Its fur is thick and crisp, and of a 

 greyish colour on the upper-parts, while on the flanks it becomes rusty yellow, and 

 beneath white. The rump is black, with a broad transverse band of white running 

 from the hocks to just above the tail; and the limbs are rusty yellow, but greyish 

 in front. The hair of the throat is elongated into a fringe. Both in habits and 

 general appearance the mara has a superficial resemblance to the hare, but the legs 

 are longer and the ears shorter and wider. It inhabits not only the barren country 

 from which it derives its name, but likewise extends northwards into the grassy 

 pampas of Argentina, where it ranges as far as Mendoza, in lat. 33 30'. On the 

 Atlantic coast, however, where the climate is moister, it only ranges as far north as 

 37 30' ; while its extreme southern limit is about the 48th parallel. 



Absolutely dry and more or less desert -like districts are 

 essential to the well-being of the mara ; and it is probable that its 

 original home was the Patagonian wastes. In Patagonia the mara is so common 

 as to form almost a characteristic feature in the landscape, Darwin observing that 

 it is usual " to see in the distance two or three of these cavies hopping one after 

 the other in a straight line over the gravelly plains, thinly clothed by a few thorny 

 bushes, and a withered herbage." Generally these rodents are found either in pairs 

 or in parties of from four to eight individuals, but occasionally in large flocks of 

 thirty or forty. They live in burrows, generally excavated by themselves; and 



