Watercolor painting on paper by Roy Gerald Krenkel, 1918 to 1983, an American book illustrator. The artwork represents a primeval man throwing a rock. Dated ca. late 1950s - early 1960s. A sketch for the The Wizard of Venus, a short story from the Tales of Three Planets, a book by American writer Edgar Rice Burroughs published in 1964. Signed by the artist in the lower right, RGK. Wooden frame. Postwar American Figurative Graphic Art, Antiquarian Librarian Collectibles.