The geographical distribution of animals, with a study of the relations ...

;chap, vii.] MAMMALIA OF THE NEW WORLD. 145extinct species. Cercolabes, the ' tree porcupine ' (Cercolabidse)has two species, one as large as a peccary ;Myopotamus, Zoncheres,Carterodon, are existing genera of spiny rats (Echimyidse)and there are two extinct genera of the same family, Lonchophorusand Phyllomys. Lagodomus (Chinchillidae), the viscachaof the Pampas, is represented by an extinct species.There is also an extinct species of Lepus ; several species ofHesperomys and Oxymycterus ;living in South America.and a large Arvicola, a genus notEdentata.—These, which constitute the great feature of theexisting South American fauna, were still more abundant andvaried in the Cave period, and it is remarkable that most ofthem are extinct genera. The armadillos are alone representedby living forms, Dasypus, and Xenurus ; Ewrydon and Heterodon,are extinct genera of the same family, as well as Chlamydotherium—hugearmadillos the size of a tapir or rhinoceros, andPachytherium, which was nearly as large. The ant-eaters arerepresented only by Glossotherium, an extinct form allied toMyrmecophaga and Manis. The sloths were more numerous,being represented by the extinct genera Ccelodon, Sphenodonand Ochotlierium, the last of large size. The huge terrestrialsloths—Megatheridse, also abounded ; there being species ofMegatherium and Megalonyx, as well as the allied Scclidotherium,supposed to have some affinity for the African Orycteropus.Marsupials.—No new forms of these appear, but numerousspecies of Didelphys, all closely allied to opossums still livingin South America.The preceding sketch of the wonderful cave fauna of CentralBrazil, is sufficient to show that it represents, in the main, aperiod of great antiquity. Not only are almost the whole ofthe species extinct, but there are twenty extinct genera, and threeothers not now inhabitants of South America. The fact that sofew remains of the living animals of the country are found inthese caves, indicates that some change of physical conditionshas occurred since they were the receptacles of so*many of thelarger animals; and the presence of many extinct genera of