When the old hen laid/ An orange one day,/ What did the little/ Chicken say?... 'Oh see the orange mar-ma-lade!'"" Professor Rees has taken the well-known riddles, usually encountered in prose, and cast them into easily memorized quatrains. While the adult mind may bend (or at least warp) under the onslaught of a whole book full, the appetite for riddles is insatiable in youngsters at this age level and a necessary stage in the development of a sense of humor. The example given above is typical of the many included here that depend on a broad play on words. Other riddles require a sharp sense of word values and a sensitive ear -- they are poetic descriptions of ordinary things. The book holds double delight -- the fun in words and their beauty, too. The audience is always ready and its teachers are always looking for something to start with in poetry. Two color illustrations by Quentin Blake are gay and sometimes hold the clue to the riddle answers which appear in small print under the rhymes.