A POETRY SHELF

On this page, Thomas D'Evelyn and Steven Ratiner look at the differences between free verse and rhymed, formal verse and informal, in contemporary poetry. Each comments on the effect when poets either shun rhyme or shape their verses with a pronounced auditory signature. The three boxed poems illustrate the variety of current styles. The following works, though not all mentioned in these two essays, served as touchstones for their discussion. LETTER FROM LOS ANGELES. By Charles Gullans, Santa Barbara, Calif.: , John Daniel, 80 pp., $8.95

FOR LOUIS PASTEUR. By Edgar Bowers, Princeton, N.J.: Princeton University Press, 1989, 66 pp., $9.95

HOUSE OF LIGHT. By Mary Oliver, Boston: Beacon Press, 80 pp., $14.95

THE COLLECTED POEMS. By Czeslaw Milosz, N.Y.: Echo Press, 1988, 511 pp., $14.95

ONE DAY. By Donald Hall, N.Y.: Ticknor & Fields, 1988, 67 pp., $16.95

OLD AND NEW POEMS. By Donald Hall, N.Y.: Ticknor & Fields, 244 pp., $24.95

LET EVENING COME. By Jane Kenyon, St. Paul, Minn.:, Graywolf Press, 70 pp., $9.95

SEAMUS HEANEY SELECTED POEMS 1966-1987. N.Y.: Farrar, Straus & Giroux, 273 pp., $20

OMEROS. By Derek Walcott, N.Y.: Farrar, Straus & Giroux, 325 pp., $25