This group includes the marsupial mammals called opossums living on the American continent. They are polyprotodont, i.e. their upper and lower jaws have five incisors. Their canines are well developed. Their hind legs are not syndactyl, and their first digit is almost opposable and has a nail unlike the other digits which have claws. Their tail is prehensile and hairless. Some species no longer have a marsupial pouch. Didelphimorphia are omnivorous and opportunistic animals. They include the Virginia opossum (Didelphis virginiana), which survives near urban areas in some parts of the USA.