Under such rhapsodic sobriquets as ""A Gratitude of Birds,"" ""A Benison of Ices and Creams,"" and ""A Discrimination of Rice and Pasta,"" veteran cookbook author Marian Tracy has assembled recipes that, whatever their claims to splendor, will look simple only to sophisticated cooks. Many, indeed, seem to come to us from Xanadu. But if culinary minimalists are horrified by Tracy's abandon here and there, catholic tastes may be tempted by mussels stuffed with currants and pine nuts, a cheese and smoked oyster souffle, or beef marrow on toast. A distillation of her wide knowledge and her special food favorites, the book contains a tribute to dried apricots featuring recipes for chutney, meatloaf, aspic, and an insidious apricothorseradish sauce. A flourish of food fantastique.