byWilliam Goyen.Clarkson N. Potter, $12.95. Arcadio, Mr. Goyen’s hermaphrodite protagonist and narrator, is the epitome of human confusion and frustration, provided one accepts the author’s underlying assumption that people do not know who they are and cannot find what they want. Arcadio’s outrageous, sometimes comic misadventures have the quality of myth; they cannot have happened, but they represent a fantastic exaggeration of what can and does happen. They are also presented in distinctive and intriguing prose.