THE RIVALS -- At the Folger through January 25.

The marriage promised to Mrs. Malaprop at the end of "The Rivals" must have been fruitful. The arch-deaconess of the misused word has certainly been as she might say, profligating since she made her debacle at Drury Lane in 1775, the most immemorable of Richard Brinsley Sheridan's impersonations.

Her descendants are treated with more respect than she. They have persuaded many people that the exact use of words isn't important because they can communicate what they mean, or because the language is changing so fast that it's impossible to pinpoint what is standard, or because their misuse is a legitimate -- argot. Mrs. Malaprop still subscribed to the belief that one should "reprehend the true meaning" of one's words, and was ridiculed by the other characters and by audiences who shared this belief.

Mrs. Malaprop and her niece, Lydia Languish, whose one requirement in a husband is that he be unacceptable to her family, ought be familiar types to modern audiences. But in the Folger Theater Group production, directed by Mikel Lambert, these two characters are played to emphasize their 18th-century quaintness.

Period language and costume, when handled as expertly as the Folger always does, are theatrical conventions that need not create psychological distance. When the actors put a certain earnest enthusiasm into comic roles, they bring us into their milieu, instead of mugging as if wild exaggeration were necessary to make them visible across the centuries. There are many well-done examples in this production, including Marion Lines as Julia, Leonardo Cimino as Sir Anthony Absolute, Ralph Cosham as Faulkland, David Cromwell as Bob Acres, Moultrie Patten as Sir Lucius and Floyd King as Fag.

But June Hansen, as Mrs. Malaprop, simpers; and Glynis Bell, as Lydia Languish, pouts. And both of them seem uncommonly smug, as if they have a superior awareness of how foolish these archaic characters were. iEach is made up to look like an antique comic doll, and whatever the historical case one can make for this look, it is no longer a convention for period plays and therefore adds to the historical distance.

An audience coming away from "The Rivals" laughing at the dear old days gone by, when people misused language or entered romance for the shock value, has gotten off too easily.