The Boston Symphony Orchestra, under the direction of M. Pierre Monteux, will give the sixth of its series of concerts in Sanders Theatre at 8 o'clock this evening. Mr. Alfredo Casella, the pianist, who has been the soloist at the Boston Symphony concerts this week, will be the soloist of the evening.

The remaining three concerts of this year's series will be given on three Thursday evenings, March 22, April 12, and May 3.

About 100 seats for tonight's concert at $1.25 are still unsold. Admission is $1.00. Tickets may be purchased at the University Book Store, Harvard Square.

Tonight's program follows: Symphony in B-flat major, Op. 20,  Chausson 1. Lent; Allegro vivo 2. Tres lent 3. Anime Concerto for Pianoforte in D minor,  Mozart 1. Allegro 2. Romanza 3. Rondo Soloist, Alfredo Casella Prelude to "Lohengrin",  Wagner Overture to "Tannhauser",  Wagner