A quadruped of the genus Phalangista, or of the subfamily Phalangistine, Australian marsupials of arboreal habits, containing numerous genera and species, usually of small size, with thick woolly fur; the typical genera (Australian opossums) have prehensile tails; the flying phalangers (called also flying opossums, flying-squirrels, or petaurists) have non-prehensile tails and a flying-membrane or parachute.