Rarely-seen plays by Arthur Miller and Tennessee Williams will be featured on the 42nd Williamstown Theater Festival season in Massachusetts June 12-Aug. 25.

Michael Ritchie will be producer of the 1996 season on the Mainstage and the Other Stage.

Mainstage Highlights:
* Arthur Miller's rewritten The Ride Down Mt. Morgan directed by Scott Elliott.

* Olympia Dukakis will star in a revival of Tennessee Williams' The Milk Train Doesn't Stop Here Anymore.

* Moliere's The Learned Ladies directed by Jim Simpson. * Eduardo de Filippo's Philumena directed by James Naughton.

Other Stage Highlights:
* Jon Robin Baitz's The End of the Day, directed by Scott Elliott. Elliott also is slated to direct a mainstage production of That play will be preceded by George S. Kaufman and Edna Ferber's ``The Royal Family,'' staged by Nicholas Martin. * August Strindberg's Miss Julie, adapted and directed by and starring Campbell Scott.