The 20th Annual Collection skims the top off the crop of shorts to appear in a variety of mystery magazines during '64. Editor Boucher notes the continuing trend toward the realistic police procedure story and leads off with H as in Homicide by Larry Treat, whom he says introduced the genre in 1945. The rest of the collection ranges over the usual variations -- hardboiled detective, favorite sleuth, satires and parodies of the form. The best of the batch is William Wiser's A SoLiLoquy in Tongues, an irreverent survey of the wild style of a self-annointed reverend gent. Boucher's introductory notes are valuable for their critical long view and there is the usual excellent bibliography list of awards and necrology.