Didelphis virginiana; Print; The Virginia opossum (Didelphis virginiana); commonly known as the North American opossum; is the only marsupial found north of Mexico. In the United States; the animal is typically referred to simply as a possum. It is a solitary and nocturnal animal about the size of a domestic cat. It is a successful opportunist. It is familiar to many North Americans as it is often seen near towns; rummaging through garbage cans; and can become a nuisance.; 1700-1880