Class [Mammalia] Linnaeus, 1758 - mammals Order Marsupialia Jameson, 1818 - marsupials see Cohort Marsupialia Jameson, 1818 Family Didelphidae Gray, 1821 - American opossums Genus Thylamys Gray, 1843 Thylamys elegans (Waterhouse, 1839) - elegant fat-tailed mouse opossum