Mass. Gen. Laws ch. 272, § 35A

Whoever commits any unnatural and lascivious act with a child under the age of sixteen shall be punished by a fine of not less than one hundred dollars nor more than one thousand dollars or by imprisonment in the state prison for not more than five years or in jail or the house of correction for not more than two and one half years, and whoever over the age of eighteen commits a second or subsequent such offence shall be sentenced to imprisonment in the state prison for a term of not less than five years.