Class Mammalia Linnaeus, 1758 - mammals Order Marsupialia Jameson, 1818 - marsupials see Cohort Marsupialia Jameson, 1818 Family Didelphidae Gray, 1821 - American opossums Genus Monodelphis Burnett, 1830 - short-tailed opossums Subgenus Monodelphis Burnett, 1830 Monodelphis theresa Thomas, 1921 - southern three-striped opossum