Dumas' death in 1968--senselessly shot by a policeman in New York: ""mistaken identity""--has doubtlessly sped along the posthumous publication of whole works (Jonoah and the Green Stone, 1976) and, as here, fragments. HIS voice has rightly come to be a major one in black writing. Two shards from novels collected here seem especially tantalizing: ""Harlem,"" in which a Malcolm-X-type street rally leader holds a 125th St. audience with a cord of hypnotizing anger and dignity; and ""Rope of Wind,"" a passionate and vivid Southern story of nightriders that's conventional enough in subject but is invested with a physicalness--Dumas can describe exactly how it feels to run in fear--that's genuinely outstanding. True, some of these pieces do falter: ""The Distributors,"" an undergraduate fantasy; and ""The Voice,"" in which adolescents sentimentally grieve over a dead friend and wonder about Godly justice. But the range of Dumas' unflashy expression--from parable to realism to preaching to fine nature writing--is truly impressive. The talent was grave and light simultaneously: it shines here, even in the most frustrating of fragments.