Section 42A. No cemetery exempted from taxation under the provisions of section five of chapter fifty-nine shall be closed for visitations between the hours of eight o'clock antemeridian and sunset, except during the months of June, July, August and September when such cemeteries shall remain open until the hour of seven o'clock postmeridian; provided, however, that the provisions of this section shall not apply on Saturdays if the cemetery is owned or used exclusively by a religious denomination which observes the Sabbath on Saturday. It shall be deemed to be a violation of this section if entrance to or exit from any such cemetery by motor vehicle is prevented during said hours, if said cemetery has accessible roads for motor vehicles; provided, however, that access by motor vehicle may be prevented on the second Sunday in May, the last Monday in May, and on Easter Sunday. Whoever wilfully violates this section shall be punished by a fine of not more than one hundred dollars.