WELDON KEES AND THE MIDCENTURY GENERATION: LETTERS, 1935-1955, edited, and with commentary, by Robert E. Knoll (University of Nebraska: $19.95; 253 pp., illustrated). Poet, cultural critic, novelist, story-writer, abstract expressionist painter, jazz musician, composer, film maker, Weldon Kees accurately termed himself "the most versatile artist now working in America." That was in 1955 when, at 41, Kees had--as he told a correspondent--"so many damned irons in the fire it looks like branding time at the old Bar Z." Beneath the froth of activity, Kees was by that time a desperate man, compulsive, manic-depressive, isolated after the breakdown of his wife and breakup of his marriage. At work on a book about nonverbal communication, he was nonetheless insufficiently adept at communication to signal his condition to friends (he would have considered such "unburdening" to be "in bad taste," one recalls). On June 1, 1955, Kees' abandoned car was found near the Golden Gate Bridge, the last trace of his apparent suicide. Scholar Robert E. Knoll here edits Kees' letters--witty, talky, newsy, charming, ironic, catty, full of literary-artistic gossip and name-dropping--and gives useful informational linkages that chronicle the career of this talented, unstable bit player in the mid-century arts game on both coasts: a figure whose marginal role provided him material for sharp epistolary commentary but not the judgment or objectivity that survival would have required.