THE EARLY forms of jazz--traditional New Orleans, Dixieland and Chicago style--have all but vanished from the local club scene and area concert halls. But don't despair, jazz antiquarians, for a dozen or so bands of that stripe regularly perform here and several have ongoing engagements. The players who comprise these bastions of musical conservatism almost without exception earn their bread at day jobs, and the gigs more often than not take place in neighborhood bars.

The music is hot and of generally good, sometimes excellent quality, and the camaraderie of the fans, old and new, is warming. Drop in on one or another of these six- or seven-piece bands and you'll immediately be energized by the kinds of sounds that rocked early century New Orleans dance halls, Prohibition speak-easies in Chicago and the low-ceilinged clubs on New York's 52nd Street in the early 1930s.

The Picayune Cabaret Band, co-led by trumpet player Tony Hagart and Bill Riddle, has for the past two years presented a recreation of the Bunk Johnson-George Lewis school of New Orleans Jazz at The Saloon on Fridays. And recently the band took on Sundays at the 219 Restaurant in Alexandria. Late on a recent Friday evening, a college-aged crowd filled the bar and most of the tables at the Georgetown watering hole while a handful of older fans sat hard by the bandstand. A beer pitcher atop a post served as a "kitty" and a sign announced that requests are $2 but that $6 is the required donation if the patron wishes to hear "Saints."

Behind the six musicians, on the front window of the establishment, was a banner with the band's logo ("Pride of New Orleans"), and on the wall to their left was a turn-of-the-century poster advertising "Ringling Bros. and Barnum & Bailey Shows." The front line of trumpet, clarinet and trombone executed the collective ensemble sound of archaic jazz over the strong and steady 4/4 beat of guitar, bass and drums. Scattered applause came from the audience as the blues ended and Hagart tapped off the next number, a rousing stomp.

Bill Riddle plays Baby Dodds style and sets his drums up in the fashion of that great New Orleans pioneer. He wields a pair of heavy sticks given to him by Tommy Benford, who recorded with Jelly Roll Morton in the 1920s. Riddle knew Dodds well, observed him in action often and corresponded with him for years. He can make the same claim about the likes of Johnson, Lewis, Jack Teagarden and a roster of other jazz greats.

Growing up in Baltimore (he moved to the Washington area in the 1950s), he was taken as a boy to see the Paul Whiteman Orchestra when cornetist Bix Beiderbecke was its star soloist, and to this day Riddle can walk up to many an older jazz luminary and be recognized and addressed as "Beale"--a nickname he acquired many years ago. He began playing drums in the 1940s and for years was a fixture in the back room of Baltimore's Martick's, a downtown saloon that featured a trio with which clarinetist Barney Bigard would jam when he was in town. Riddle has played with several D.C. area bands, including the Federal Jazz Commission, and currently divides his time between the Picayune Cabaret Band and the Sunshine Skiffle Band.

Reminiscing about musicians he has known, Riddle laughingly recalled a party in the 1950s attended by the late violinist Stuff Smith. "It was about 6 o'clock in the morning and he asked for a drink and we had drunk everything in the house. Stuff said, 'out on the desert and not a drop to drink,' and then he started playing 'Caravan'." Riddle can also tell stories about, for example, the visits he and others made to hear Jelly Roll Morton at the Jungle Inn on U Street NW in the late 1930s. "I brought 16 people over from Baltimore and Jelly had to send out for whiskey."

"There's a lot there in that style, a lot that people can enjoy doing and listening to," observes co-leader Hagart of the idiom to which he devotes much of his spare time: researching sheet music of old tunes and noting the way in which they were played on 78 rpm records, rehearsing the band, and writing scholarly articles for jazz periodicals and liner notes for reissue sets. Hagart's devotion to authenticity is so pronounced that he even plays a trumpet of mid-'20s vintage. "This older horn has a narrow bore," he explains, and it enables him to "speak with a voice that can be quiet and still be distinguished from the other instruments."

Other regular gigs of traditional style jazz bands include the Buck Creek Jazz Band's alternate Sundays at the Springfield Hilton, the Federal Jazz Commission's Tuesdays at Col. Brook's, and Southern Comfort's Fridays at Shakey's in Rockville. But the action doesn't stop there.

The nonprofit Potomac River Jazz Club's "hot line" (532-8723) provides a weekly update of information about the activities of a number of other Washington and Baltimore jazz bands and combos that play in the old styles.