The Rodents of the genera Capybara, Agouti, and Paca, are widely diffused over the plains of Tropical America. Of the three, the Capybara (_Hydrochærus capybara_) is the largest. He attains the size of a sheep, has a voluminous head, small round ears, eyes large and black, a thick divided nose flanked by formidable whiskers, a short neck, a thick body covered with short, coarse, russet hair, and short legs; altogether, _not_ a "thing of beauty." Like the peccary, he is tailless, and in a manner web-footed, being thus adapted for a semi-aquatic life. These great Rodents, says the illustrious author of "The Origin of Species," in one of his earlier works,[135] are generally called "_Carpinchos_;" they occasionally frequent the islands in the mouth of the Plata, where the water is quite salt, but are more abundant on the borders of fresh-water lakes and rivers. In the day-time they either lie among the aquatic plants, or openly feed on the turf plain. When viewed at a distance, from their manner of walking and colour, they resemble pigs; but when seated on their haunches, and attentively watching any object with one eye, they re-assume the appearance of their congeners, the Caries. Both the front and side view of their head wears quite a ludicrous aspect, from the great depth of their jaw. The Capybara leads no joyous life apparently, for in the water he is perseveringly pursued by the crocodile, and in the plain by the jaguar. He runs so awkwardly as to be easily caught by hand, and the South Americans profess to relish his flesh. The Paca (_Coelogenys_) differs from the Capybara in the complex structure of his molar teeth. He inhabits the woody regions of South America, where he is generally found in the vicinity of water, concealing himself in burrows so near the surface, that the pedestrian's foot often intrudes within them. His form is thick and clumsy, spotted with white on the sides, and intermediate in size and appearance between a hog and a hare.[136] He is about a foot in height and two feet in length, with hind limbs much longer than the fore, but considerably bent. The claws are thick, strong, and conical; the eyes large, prominent, and of a brownish hue; the ears nearly naked, and whiskers rigid. The paca is heavy and corpulent, but swims and dives with remarkable agility. As he feeds only on fruits and tender plants, his flesh is exceedingly savoury, and a staple dish in many parts of America. His burrow is provided with three apertures, and his capture is managed by closing up two of these, and digging up the third.