The Didelphyidæ, or true opossums, range throughout all the wooded districts of the Neotropical region from the southern boundary of Texas to the River La Plata, and on the west coast to 42° S. Lat., where a species of _Didelphys_ was obtained by Professor Cunningham. One species only is found in the Nearctic region, extending from Florida to the Hudson River, and west to the Missouri. The species named _Didelphys californica_ inhabits Mexico, and only extends into the southern extremity of California. The species are most numerous in the great forest region of Brazil, and they have been recently found to the west of the Andes near Guayaquil, as well as in Chili. The exact number of species is very doubtful, owing to the difficulty of determining them from dried skins. All but two belong to the genus _Didelphys_, which has the range above given for the family (Plate XIV., vol. ii. p. 24); _Chironectes_ (1 sp.), the yapock or water opossum, inhabits Guiana and Brazil; _Hyracodon_ (1 sp.), is a small {249}rat-like animal discovered by Mr. Fraser in Ecuador, and which may perhaps belong to another family. _Extinct Didelphyidæ._--No less than seven species of _Didelphys_ have been found in the caves of Brazil, but none in the older formations. In North America the living species only, has been found in Post-Pliocene deposits. In Europe, however, many species of small opossums, now classed as a distinct genus, _Peratherium_, have been found in various Tertiary deposits from the Upper Miocene to the Upper Eocene. We have here a sufficient proof that the American Marsupials have nothing to do with those of Australia, but were derived from Europe, where their ancestors lived during a long series of ages. FAMILY 77.--DASYURIDÆ. (10 Genera, 30 Species.) GENERAL DISTRIBUTION. __________________________________/\__________________________________ / \ NEOTROPICAL| NEARCTIC |PALÆARCTIC | ETHIOPIAN | ORIENTAL | AUSTRALIAN SUB-REGIONS|SUB-REGIONS|SUB-REGIONS|SUB-REGIONS|SUB-REGIONS|SUB-REGIONS. -----------+-----------+-----------+-----------+-----------+------------ | | | | | -- -- -- --|-- -- -- --|-- -- -- --|-- -- -- --|-- -- -- --|1. 2 -- -- | | | | |