OPOSSUM (front the American Indian name). The opossum (Didelphys n•irqiniamUb is certainly the most distinctive and characteristic of American mammals, for not alone is it found only in America. hut it is with a single exception (see 1 IABSLTPIALIA ) the only marsupial mammal found in the States, and the family. to which the name opossum is now universally ex tended. does not occur except in America. This family. the Didelphidie, is characterized, in dis tinction from the other marsupials, by numerous (181 small, subequal incisors. the canines larger. the molars with sharp cusps, and the hind feet with the four outer toes subequal, distinct, and having a well-developed, opposable hallux. The tail usually is long, naked, and prehensile. The marsupial pouch is complete in the common opos sum, but in most of the family it is,rudimentary or wanting. The family includes only one genus besides Didelphys, and that is ChironiA.tes, which contains the single species rarie jolts, the 'yzt pock' (q.v.) of South America.
The common or 'Virginia' opossum is widely distributed in the United States. It ranges as far north as southern New X ork State and south ern Michigan; southward it extends through Mexico into Central and perhaps South America. The opossum is about as large as a big cat; it has rather short but equal legs, and a somewhat pig-like snout. The hair is coarse. of a yellowish tint, the tips of the hairs on the back and sides brownish or blackish, and intermingled with these are larger white hairs. The tail is scaly like that of a rat, but is hairy at the base. The brain is small, but the senses of smell and sight are well developed. The opossum is ordinarily a soli tary animal, and except during the breeding two individuals are seldom found together. It is not exclusively arboreal. though fitted especially for such a life. It makes its retreat for the day chiefly in hollow trees, for it is nocturnal in its habits. The young, six to twelve in number, are brought forth in a nest of dried grass and leaves in some hollow in a stump or tree. The embryonic life lasts only about twenty-six days, when the young are born in a helpless condition and are transferred by the mother to the teats, where they are concealed and protected by the pouch. (See They are at this
time about the size of young mice. but grow rapidly and at the end of six weeks are large enough to leave the pouch and run about, but for the first few weeks thereafter they return to the pouch for shelter and protection. The food of the opossum is chiefly insects, but almost any available animal food will be used, especially reptiles, and birds' eggs and young. As an article of food the animal is in particular demand among the negrocs of the South. Under the stress of capture, the opossum has the remarkable habit of simulating death, lying with closed eyes and limp muscles, until a favorable opportunity to make its escape. When so simulating, no amount of handling, kicking, or ordinary abuse will cause the animal to show signs of life, but if tossed into water it realizes its peril and resumes activity with great promptness.
The number of species of Didelphys and their geographical limitations are still in doubt, on account of great individual diversitY, but there are probably about twenty good species, nearly all smaller than the common opossum, and many no larger than rats. The crab-eating opossum (Didelphys cancrirora) is an interesting Brazil ian species, which feeds chiefly upon crustacca and is consequently found most commonly in swamps. One of the species from Surinam Didelphys dorsigcra) carries the young, after they leave the teats. on the back of the mother, with their tails twilled around hers, and this method of caring for the young is common to various other species in which the pouch is rudi mentary or wanting. Several of the Peruvian opossums are remarkable from their habit of living mainly upon fruit. Among the smallest species may be mentioned the mouse-opossum (Didelphys marina), a little larger than a mouse, bright red in color, and ranging from Mexico through Brazil; and the three-striped opossum (Didelphys Americana) of Brazil, which is very small and shrew-like, without a prehensile tail, of a reddish-gray color, with three distinct black stripes down the back. The name opossum is used in Australia for several mammals of widely different families, and not entitled to the name. See Colored Plate of Massumus; and Plate with CARNIVORA.