NEW HAVEN, Conn., Jan. 19--New Haven police arrested three more Yale students today as they continued their investigation of sex antics in a Yale dormitory involving a group of students and a 14-year-old girl.

Three other students were arrested Monday. Police said the girl--who has been referred to juvenile authorities--picked out their pictures in a Yale yearbook and then identified them in person at police headquarters.

Those arrested today, all juniors, were Jack F. Adler, Jr., 20, of Elkins Park, Pa.; Stephen White, 19, of Paterson, N.J.; and Donald B. Murphy, 19, of Chappaqua, N.Y.

The charges against all arrested so far is lascivious carriage, which covers a variety of sexual misdemeanors. It carries a maximum sentence of six months in jail, a $100 fine, or both. The students will appear in city court Jan. 27.

After several days of dodging the question, Yale confirmed yesterday that 12 students had resigned from the university and left last week.

Police say that when all arrests have been made, the total of students involved may be 15 or more.