by Carroll & Graf, $16.95. Mr. Olinto is a retired Brazilian diplomat who, while serving as cultural attache in Lagos, studied the links that survive between Brazilians of African descent and their ancestral homeland in Nigeria. He has converted his findings into this novel about the Silva family, former slaves who return to Nigeria and prosper. Their success is due to the enterprise of Mariana, who begins as a bewildered child dragged along by her grandmother and ends as the matriarch of a clan. Her progress involves many years and many people—rather too many of both in terms of narrative tempo. Much of what Mr. Olinto includes in the story is of interest for the light it throws on Nigerian society and on the crisscross of tradition and trade over the Atlantic, but much of it is also of minor importance in relation to Mariana’s affairs. The novelist has resolutely reported all he knows. The reader may be tempted to skip., translated by .