Any trust fund established for retirement purposes by a county and which was on June 21, 1961, in the possession of the State Treasurer shall be transferred to the State Employees Retirement Fund. Each employee for whom such trust fund was established and who was employed by the state on said date shall be credited for as much county service computed in accordance with section 5-184 as his share in such fund will provide, provided such contributions shall not be refundable in the event of termination of service by such employee.