The BOLIVIAN CAVY (_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 ROCK CAVY (_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 SOUTHERN CAVY (_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 PATAGONIAN CAVY or 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. [Illustration: PATAGONIAN CAVY.]