Baring-Gould’s sources: AH Latin Martyrotogies. Roman Martyrology. Authority: — The Acts of S. Sebastian. ) Marcus and Marcellinus were twin brothers of a noble family in Rome, who had been converted and baptized in their youth and were married. Diocletian ascended the imperial throne in 284, and before he issued his edict of persecution, the Christians in the capital and elsewhere suffered from popular tumults, or the ill-will of cruel magistrates. Marcus and Marcellinus were thrown into prison, and condemned to be beheaded by Chromatius, the lieutenant of the prefect of Rome. Their friends obtained a respite of thirty days, in which they hoped to prevail on them to comply with the laws, and adore the gods of the state religion. For this purpose they were removed from prison to the house of Nicostratus, the registrar. Tranquillinus and Maria, their parents, in company with their wives and little ones, visited them, and endeavoured to shake their constancy by their tears. But S. Sebastian visited them and encouraged them. He succeeded in converting both Tranquillinus and Maria, and afterwards by loosening the tongue of Zoe, the wife of Nicostratus, converted him also, and soon afterwards Chromatius, who set the saints at liberty, and abdicating the magistracy, retired into the country. Marcus and Marcellinus were hidden by a Christian officer named Castulus, in his apartments in the palace of Diocletian, but were betrayed by a false Christian, Torquatus, and were re-taken. Fabian, who succeeded Chromatius, ordered them to be tied, and their feet to be nailed to a wooden post. The brothers bore their pains with great cheerfulness, and sang, “ Behold how good and joyful it is, brethren, to dwell together in unity.” After having been thus exposed for a day, they were run through with lances. Their bodies were laid in the catacomb which has since borne their name, and are now in the church of SS. Nicolas and Praxedes at Rome, but portions at Bologna, Volterra, and Soissons.1