* The Claremont Quartet will present a series of five concerts of Beethoven String Quartets on Thursday evenings ers Theatre. Tickets (1 single of $4.25 ers Theatre. Tickets (1 singe or $4.25 for series) will be sold at Matthews 4 or at the door.

* Through July 7 students may register in Matthews 4 for a tennis tournament which starts July 10. Tennis instruction ($4 an hour, private; or $5 for six group lessons) is also available starting July 5.

* A bus tour to Tanglewood for a weekend of Boston Symphony music July 28-30 is available to a limited number of 28. Sign up in Matthews 4.

* Poetry readings in air-conditioned Lamont at 4 p.m. Wednesdays will be by Sean O'Criadain (July 12); Katherine Hoskins (July 26); Arthur Freeman (August 2); and William Alfred (August 9). The July 19 reader will be announced later.

* Radcliffe's four tennis courts and two practice courts will be open to Summer School students (50 cents an hour) from 10 a.m. to 12 m and 3 to 8 p.m., dally.

* Tryouts for G. B. Shaw's Misalliance, to be produced at Loeb Drama Center, will be held Thursday for all School students and faculty at 10 a.m. and 2 p.m. at Loeb Rehearsal Room D, 64 Brattle St.

* Durham Miller, a graduate student in world politics, has announced an organizational meeting at 6:30 p.m. Tuesday and Thursday in Emerson H for students interested in meeting regularly to discuss problems, theories and prospects of the cold war.

* Crimson Key tours of the University leave each weekday from the tent by Massachusetts Hall at 10 a.m., 11:15 a.m., 2:15 p.m., and 3:15 p.m. Sundays: 1:30 p.m. and 2:45 p.m.

* Two Harvard undergraduates will present the first of a series of dances this Wednesday from 8 p.m. to 1 a.m. at the Sherry-Biltmore Hotel in Boston. (Folksinging all night and music of the Carlton Brothers.)

* Busch-Reisinger Museum, Kirkland St. and Divinity Ave., announces a series of record music concerts in its garden, 1-2 p.m., Monday through Friday. Each Wednesday, musical compositions related to art will be heard. This week: Bartok, Quartet no. 3-4; Beethoven, Septet; Mozart, Piano concertos no. 19 and 23; Handel, six concerti grossi; and Mozart, Divertimento no. 3. Next week: Clementi, Piano sonatas; Bartok Two Portraits for Orchestra and Deux Images (Wednesday); Beethoven, Quartets no. 1-2; and Brahms, Concerto for Violin and Orchestra.

* Casting for the Harvard Opera Guild's production of Orpheus in Hades will be held today and Tuesday (7-11 p.m.) and Wednesday (2-7 p.m.) in the Loeb Experimental Theatre.