Earlier this fall, playwright John Guare announced that New York's Signature Theatre Company would conclude its season dedicated to him by performing, in repertory, the three plays of his "Nantucket" series, plus his new work, The Book of Judith. Now however, that monumental event may not happen.

The problem is the costly nature of the venture. Mounting the quartet of plays would involve a great outlay of money, much of it on a 30-member cast. As a result, Signature may replace the planned series with a single new Guare play, as yet unnamed. A Signature spokesman said a decision will likely be made by the end of the week.

The "Nantucket" series follows a group of idealistic 19th century characters and their attempts to create a utopian society. The plays include Gardenia , Lydie Breeze , Women in Water as well as the new Judith.

Guare's Bosoms and Neglect, starring Mary Louise Wilson, is currently playing at the Signature.

* In other Signature news, the company may commission a new play from dramatist Maria Irene Fornes for the 1999-2000 season, which will be dedicated to the playwright. Press rep James Morrison said the premiering of a new work each year has become something of a tradition at the theatre, which dedicates each season to one playwright. No title has been attached to the new work.

Fornes, an experimental dramatist, has worked Off-Broadway and Off-Off Broadway for 30 years. Her latest play, The Summer in Gossenssass, looked at the influence of Hedda Gabler on the women of its generation. Other Fornes plays include Mud, Fefu And Her Friends, Abingdon Square, Terra Incognita and The Conduct of Life.

For memberships and information on the Signature Theatre season call (212) 244-PLAY.

-- By Robert Simonson