An Eliot House junior got himself arrested and spent Thursday night in jail by mistaking an irate Cambridge policeman for a "phony."

The student, who prefers to remain anonymous, was returning from Radcliffe at 3 a.m., when he claims he was assaulted by two local youths. They grabbed his arms and ripped the buttons on his "long black cape," he said.

Then Cambridge officer "300" came on the scene, and instead of rescuing the harassed student helped the two attackers rifle his pockets, the student said. "His badge looked very tinny under the artificial light of the street lamp," he said, "and when I touched the badge, he arrested me."

Later, Cambridge Police Lieutenant J. Harry McCaffrey said that the student was insolent to the officer, and that he was arrested because he could produce no identification. He would neither give his name nor "a good account of himself," McCaffrey said last night.

But the student countered by accusing the police officer of abusive treatment in arresting him. When he protested his innocence the officer called for assistance from six policemen and two prowl cars.

While at the police station, the student continued, he was denied permission to call his Senior Tutor, John Conway.

Hold over night in East Cambridge jail, the student had to sign a statement that he would not protest police treatment, before his release. He was offered the alternative of appearing in court yesterday morning, but chose to sign the release instead, McCaffrey said.