NEW YORK, Nov. 13.—(4#)—Eudora Welty today was named first prize winner in the 24th annual O. Henry memorial competition for short stories published in American magazines. The award committee said it chose the Jackson, Miss, author for her “The Wide Net,” which appeared in Harper's magazine. First prize is 3300. Other prizes; second ($200) to Wal lace Stegner, Harvard university English faculty, for “Two Rivers’; third ($100) to Wilbur L. Schramm, Iowa State university English pro fessor, for “Windwagon Smith.” Both were published in Atlantic monthly.