Odysey, Mirror of the Mediterranean, photographed and designed by Roloff Beny. Text and Anthology by Anthony Thwaite. New York: Harper & Row. 360 pp. $ 85.

The Linzertorte of recent coffeetable books, Roloff Beny's album of evocative photographs of the Mediterranean is a romantic, extravagant confection. Beny, a noted photographer of landscapes and ruins, has been snapping the Mediterranean for 30 years, and this book is a miscellany, illustrating his love affair with the region from the Levant to Gibraltar, from Venice to Algiers.

The Mediterranean is a broad subject, the fluid center into which the waters, cultures, and histories of three continents - Europe, Africa, Asia - have spilled and mingled. To provide focus and lend cohesion to the book, British poet Anthony Thwaite has contributed an informative, wide-ranging text that touches on history, geography, and literary selections inspired by the area. Homer, Goethe, Neruda, and Durrell are among those quoted.

Buyers should beware, though. ''Odyssey,'' like the Linzertorte, is not without its drawbacks. Each rich layer contains much that is simply sweet fluff and little that is truly nutritious. Overindulgence may lead to a feeling of glut; on the other hand, each individual bite is a luscious pleasure.