The subject of islands lends itself easily to a romantic-enigmatic treatment, and Jane Yolen has put together a generally satisfying collection of both obvious and out-of-the-way teasers. There are local legends about ghosts and pirate treasures and shipwrecks, a short roundup of moving, disappearing or dubiously charted islands, an observer's report on the actual "birth" of Surtsey island just below Iceland, and a trio of longstanding puzzles: the anthropological/logistical one of Easter Island's great sone faces, the biological one, pursued by Darwin, of the Galapagos Islands, and — inevitable — the ancient one of Atlantis, which was possibly a combination of Them and Crete. Just as puzzling is the choice of illustrator for a book that depends on a mysterious, evocative mood — but as the pictures are savingly in black, gray and white, a suitably fog-shrouded impression is maintained throughout.