CORREGIDORA by GAYL JONES 185 pages. Random House. $6.95.
It seems unpromising material for a novel, and the author's plot is apparently more suited to pulp melodrama than to serious fiction. Her book begins with a young black woman improbably named Ursa Corregidora and plunks her down in a seedy Kentucky dive in the 1940s where she works as a blues singer. Enter Ursa's jealous husband, Mutt Thomas, who hurls the heroine down a staircase, injuring her so badly that her womb has to be removed. Twenty years pass. Ursa's second marriage fails. Her career takes her no higher than another dive...