(a) The employees of any county participating in chapter 48 of the general statutes, revision of 1949, who were taken into state service under the provisions of section 1464d of the 1955 supplement thereto shall be credited with their entire period of service as employees of such county for retirement purposes; provided there has been transferred to the retirement fund from the Municipal Employees’ Retirement Fund the amount paid into said municipal fund under the provisions of section 894 and subsections (b) and (c) of section 895 of the general statutes, revision of 1949, on account of the service of such employees as county employees, plus such amount as the Retirement Commission determined, on sound actuarial principles, represented the contributions to said municipal fund made by such county under subsection (a) of section 895 on account of the prior service of such employees, together with interest at the rate of two and one-half per cent compounded annually from the date of each such payment into said municipal fund to the date of transfer of such employees into state service, less any amount expended from said municipal fund by the Retirement Commission as compensation for actuarial services in connection with the computation of such amount.

(b) The contributions made by any such employee to the Municipal Employees’ Retirement Fund and so transferred under the provisions of this section may, if such employee leaves the employment of the state before becoming eligible to retire, be withdrawn by him, on request, without interest, in the same manner as is provided in § 5-166 for the withdrawal of his contributions to the State Employees Retirement Fund.