During a career that stretches back three decades, Mason "Country" Thomas has played with most of this area's jazz musicians and in too many clubs to begin naming.

Last night at Ashby's in the Washington Hilton Hoten his quartet opened the first set with Cole Porter7s "I Love You," and his tenor sax was both lush and tough as he built up and then took apart the melody.

Another ballad, the Rodgers and Hart composition "My Romance," well displayed his full, big sound with the occasional wispy phrase and a touch of vibrato. Thomas' vocabulary is full of little riff-like phrases, but there is not a cliche among them.

The quartet picked up the tempo on Earl Hines' "Rosetta," on which Thomas switched to clarinet, playing with a clean, round tone in middle register and slipping into high with ease.

Its if a tight, tasteful and swinging foursome: Thomas and his facile and inventive guitarist, Paul Wingo, picking up on and exploring each other's lines, and bassits Scot Giambusso and drummer Jack Connors (subbing for Chuck Redd) laying down a smooth but tension-filled carpet of rhythm.

The Mason Thomas Quartet will continue nightly except Sundays at Ashby's.