Class Mammalia Linnaeus, 1758 - mammals Order Marsupialia Jameson, 1818 - marsupials see Cohort Marsupialia Jameson, 1818 Family Didelphidae Gray, 1821 - American opossums Genus Marmosa Gray, 1821 - murine opossums Subgenus Marmosa Gray, 1821 Marmosa murina group see Subgenus Marmosa Gray, 1821 Marmosa canescens (J.A. Allen, 1893) - greyish mouse-opossum see Tlacuatzin canescens (Allen, 1893)