RIDE A PURPLE PELICAN

Two sparkling talents combine to produce a book that promises more than it delivers. ""Grandma Bear from Delaware/rocked in a rickety rocking chair,/socks on her feet and a ribbon in her hair,/Grandma Bear from Delaware."" Prelutsky's 28 short verses exhibit his usual wonderful ear for nonsense sounds and rhymes, but the imaginative silliness that informs his best work seldom shows itself, and the device of beginning and ending with the same line is overused. Several (""Bullfrogs,"" ""I'm a yellow-bill duck"") do lend themselves to audience participation, and a few (""Early one morning,"" ""Molly Day"") probe more deeply into things and cross over into poetry. This is more than can be said for the illustrations, which, though they feature Williams' delicate line and some brilliant colors, seldom achieve more than a literal rendering of the accompanying text--and that often awkward. A handsomely designed, very disappointing collection.