Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 160, § 187

A railroad corporation may make contracts for the conveyance of passengers upon designated trains for a specific distance at fixed times, at such reduced rates of fare as the parties may agree upon. Tickets may be issued for such passengers, upon which shall be plainly printed the terms upon which they may be used. Such tickets shall not be transferable without the consent of the corporation, nor shall they entitle the holder to ride upon a train not therein designated.