THURSDAY

Musica Orbis, a five-piece folk-rock-jazz-classical ensemble currently touring the Boston area plays a one-night stand in a Cambridge night spot. The Idler, 123 Mt. Auburn St., 9 p.m.

Chamber Music and Dancing featuring Shann Jacobsen, piano; Wendy Holdaway, bassoon; Kathleen Watt, soprano. Pieces by Vivaldi, Mozart and Barber to be followed by waltz and other dances. Kirkland JCR, 8:30 p.m.

Radcliffe Choral Society joins in concert with the Glee Club of the University of Virginia to sing Verdi, Brahms, Schutz and Caplet. Priscilla Chapman, conductor. St.Paul's Church, 8 p.m.

FRIDAY

Harvard-Radcliffe Orchestra presents the third of four seasonal concerts. James Yannatos, conductor and David Commanday '76, cellist. Works of Mozart Bloch, Hindemith. Sanders Theater, 8:30 p.m.

SATURDAY

Songs sung by David Booth and friends, Dunster Library, 5:30 p.m.

Cello-Piano Recital given by Egbert Hoogenberk and Meg Heaton doing warhorses by Bach, Debussy and Franck. Kirkland JCR, 8:30 p.m.

SUNDAY

Wellesley Chamber Singers take a shot at Byrd, Britten, Tallis, and Palestrina. Dunster Library, 3 p.m.

MONDAY

The Fromm Foundation sponsors Tashi, an avante-garde classical chamber music group comprised of piano, violin, cello and clarinet. Peter Serkin, director. Sanders Theater, 8 p.m.