Nearly 80 pickets, their signs calling for withdrawal of U.S. troops from South Vietnam, demonstrated in the Square Saturday amid sporadic heckling from a number of spectators.

For slightly more than an hour, beginning at 1:10 p.m., the marchers peaceably walked in a long elipse along the wall at the Southwest end of the Yard just opposite the Kiosk. The demonstrators, most of them from Toscin, the Harvard-Radcliffe Socialist Club, and the Young Socialist Alliance--the three sponsoring organizations--handed out copies of a policy statement during the picketing.

The statement said that the "'Vietcong' are South Vietnamese peasants in revolt against a dictatorial government" and that the "present U.S. position is untenable. The administration is considering extending the war to North Vietnam. This is morally unjustifiable and a threat to world peace. We must withdraw."

"We Want Marx"

Curious crowds gathered around the Kiosk, on the Mass. Ave. traffic island opposite the demonstrators, and on the sidewalk where the picketing was occurring. The first trouble came at about 1:25 p.m. when some people standing on the traffic island began chanting "We Want Marx" and "McNamara for President."

Several of the spectators continued yelling taunts at the marchers for about five minutes. "They're crusading for NOTHING," one of them cried. At this point, a policeman commanded the apparent leader to keep quiet, and, a minute later, police ordered the traffic island to be cleared of all spectators.

Later in the afternoon, however, another group of about 10 spectators began to form a human wall across the sidewalk to prevent the marchers from continuing in their elipse. After rejecting the request of Mary S. Gillmor '64, a demonstration organizer, to leave the sidewalk, the group was dispersed by a policeman.

Shortly before 2 p.m. three supporters of the conservative Young Americans for Freedom decided to join the picketing with a large sign declaring the "Y.A.F. Backs Our President in Viet Nam."

Police hauled the three out of the picket line a few minutes later and gave them a lengthy lecture.

At about 2:05 p.m. the demonstrators unexpectedly began a slow march from the Square to the Cambridge Common, their starting point. Originally, the picketing was scheduled to last from 1 to 3 p.m., but as Schneider's band started to march toward the Square on the way to the International Student Association's Fun Fair, leaders of the picketing decided to return to the Common.

They said their presence would have been "incongrnous" with the appearance of Schneider's band, but they were also reportedly worried that their numbers might diminish by 3 p.m