Class Mammalia Linnaeus, 1758 - mammals Order Didelphimorphia Gill, 1872 Family Didelphidae Gray, 1821 - American opossums Subfamily Didelphinae Gray, 1821 Genus Monodelphis Burnett, 1830 - short-tailed opossums Monodelphis maraxina Thomas, 1923 - Marajó short-tailed opossum