Section 33A. If it appears from the statements made in the written notice of intention of marriage that a party to such intended marriage is under eighteen, the clerk or registrar shall not, except as required under section twenty-five, issue a certificate under section twenty-eight before receiving proof of the age of the parties. Such proof shall be contained in any of the following documents, graded and taking precedence in the order named: (1) an original or certified copy of a record of birth; (2) an original or certified copy of a baptismal record; (3) a passport; (4) a life insurance policy; (5) an employment certificate; (6) a school record; (7) an immigration record; (8) a naturalization record; or (9) a court record. Documentary evidence of a lower grade as aforesaid shall not be received by the clerk or registrar unless he is satisfied that evidence of a higher grade is not readily procurable. If no such documentary proof of age is procurable, the consent of the parent shall be sufficient. If the clerk or registrar has reasonable cause to believe that a party to an intended marriage represented to be eighteen or over, is under such age, he shall, before issuing such certificate, require documentary proof of age as aforesaid.