CALLISTO, in Greek mythology, an Arcadian nymph, daugh ter of Lycaon and companion of Artemis; probably a local form of Artemis Kalliste (fairest). She bore Zeus a son, Areas, the ancestor of the Arcadians, and was transformed into a bear by Hera, Zeus, or Artemis. Areas, when hunting, encountered the bear Callisto, and would have shot her, had not Zeus carried up both to the skies, where he placed them as constellations.