CRADLE by Arthur C. Clarke and Gentry Lee (Warner: $4.95). Photojournalist uncovers an object beneath the sea that could trigger the extinction of mankind.
MIDNIGHT BLUE by Dorothy Garlock (Warner: $4.95). Mara McCall entreats a lusty hired hand to help her reclaim her family's once-prosperous ranch.
THE RELUCTANT RONIN by James Melville (Fawcett Crest: $3.50). Japanese Superintendent Otani investigates the murder of a Dutch woman whose personal effects include a picture of his family.
RETURN TO EDEN by Harry Harrison (Bantam: $4.95). Conclusion of Kerrick's prehistoric conflict with the saurian Yibane.
SENATORIAL PRIVILEGE: The Chappaquiddick Cover-Up by Leo Damore (Dell: $4.95). Damore claims to offer previously concealed answers to several significant questions stemming from this 20-year-old incident.
RAINBOWS, CURVE BALLS: And Other Wonders of the Natural World Explained by Ira Flatow (Perennial: $7.95). Underlying scientific explanations of common and mysterious occurences, such as sand at the beach, microwave ovens, black holes and flight.
HIDDEN HISTORY: Exploring Our Secret Past by Daniel J. Boorstin (Vintage: $9.95). Historian and Pulitzer-Prize winning author uncovers some of the unfamiliar information that affected American history.
MODERN MADNESS: The Hidden Link Between Work and Emotional Conflict by Douglas LaBier (Touchstone: $10.95). Study of the relationship between personal and job satisfaction among today's urban careerists.
LAST DAYS OF THE SICILIANS: The FBI'S War Against the Mafia by Ralph Blumenthal (Pocket: $4.95). The 1987 convictions of 18 known mob members began with the investigation of a pizza parlor that served as the hub of a billion-dollar drug operation.
SELF-HELP / REFERENCE
MOUNTAINS: A Natural History and Hiking Guide by Margaret Fuller (Wiley: $12.95). Information on geology, ecology, plant life, wildlife, weather and climate.
BRIDGE IN THE FOURTH DIMENSION by Victor Millo (Fireside: $7.95). The psychology of some of the most common types of players is explored.