GROUCHO: One morning I shot an elephant in my pajamas. How he got in my pajamas, I'll never know. . . ZEPPO: The garbage man is here. GEROUCHO: Tell him we don't want any. . . MARGARET DUMONT: Judge Chanock will sit on my left hand and you will sit on my right hand. GROUCHO: How will you eat--through a tube? . . . Octogenarian Groucho is in good form, taking clear pleasure in reviewing his life's work, not only quoting the mellowest line from old scripts (""Either this man is dead or my watch has stopped""), but also keeping brazenly insightful in his present tense. He pulls no punches assessing the quality of the less happy Marx Brothers flicks. The book features nearly 1,000 illustrations and Groucho's expansive captions. Feeling no need to score every moment, he is relaxed but shows a steel-edged charm as he pastes up the best Marx Brothers book yet.