Poland approved a limited amnesty for some political prisoners and common criminals, but top leaders of the Solidarity underground movement were not eligible. About 350 political prisoners are presently in Polish jails. It was not immediately known how many will be affected. The amnesty measure offers some Solidarity activists, underground since the movement was banned, a pardon for their alleged crimes against the state if they surrender to the police by Dec. 31. Solidarity founder Lech Walesa was unimpressed. "The mountains have brought forth a mouse," he said.