THE CATHERINE WHEEL (281 pp.)Jean StaffordHarcourt, Brace ($3).
A SEASON IN ENGLAND (304 pp.)P. H. NewbyKnopf ($3).
SYBIL (284 pp.)Louis AuchinclossHoughton Mifflin ($3).
Once upon a time, many good people considered that reading novels was a sin comparable to sloth. When good novelists, with the help of critics and changing times, made the habit respectable, fiction began to outsell nonfiction. During the past few years, the novel has lost ground so rapidly that 1951 may be put down in literary histories as the year of the great debate: What is the novel's futureif any? It is...