Percy and Willie Humphrey, the key figures in the Preservation Hall Jazz Band, were listed in the program at Wolf Trap Monday night. But the brothers, 85 and 89, respectively, were home in New Orleans, playing at the band's namesake club. The Humphreys had decided to pass up the band's East Coast swing and the attendant rigors of travel. Their absence underscored the fact that our connections to pre-World War II New Orleans jazz are rapidly disappearing, making each visit of this band that much more important.

The Humphreys were missed, but seven regulars from the nightly rotation at the French Quarter club were on hand and played superbly. The focus shifted to two relative youngsters, the 81-year-old Kimballs -- Jeannette on piano and Narvin on banjo -- who anchored a rhythm section that syncopated blues and dance tunes with miraculous simplicity.

The whole septet played with the same economy, with David Grillier's sweet clarinet tone weaving through the slurred brass notes of Wendell Brunious's trumpet and Frank Demond's trombone. When Narvin Kimball, his hair snow white, stood up to croon "Georgia on My Mind," his voice was as clear and strong as ever.