MEMENTO MORI (224 pp.)Muriel Spark Lippincott ($3.95).
When the geriatricians have succeeded in adding another age to Shakespeare's seven, what will all the porcelain teeth chatter about? The same old things, answers thirtyish Author Spark in this novel of arthritis and ague. None of her major characters will see 70 again, but since no sin has yet proved deadly, the reasoning of the ancients seems to run. there is reason to hope that wrongdoing may even be healthful. So they tyrannize each other, gloat over signs of decrepitude in contemporaries, stir the ashes and the urns of old loves with gossip. One...