The time soon came when these frank avowals of Christianity were either impossible or extremely hazardous; and although legally a tomb continued to be a _locus religiosus_, no matter what the creed of the deceased had been, a vague sense of anxiety was felt by the Church, lest even these last refuges should be violated by the mob and its leaders. Hence the extraordinary development which underground cemeteries underwent towards the end of the first and the beginning of the second century. These catacombs were considered by the law to be the property of the citizen who owned the ground above, and who either excavated them at his own cost, or gave the privilege of doing so to the Church. This is the reason why the names of our oldest suburban cemeteries are derived, not from the illustrious saints buried in them, but from the owner of the property under which the catacomb was first excavated. Balbina, Callixtus, Domitilla were never laid to rest in the catacombs which bear their names. Prætextatus, Apronianus, the Jordans, Novella, Pontianus, and Maximus, after whom other cemeteries were named, are all totally unknown persons. When these cemeteries became places of worship and pilgrimage, after the Peace of Constantine, the old names which had sheltered them from the violence of persecutors were abandoned, and replaced by those of local martyrs. Thus the catacomb of Domitilla became that of Nereus and Achilleus; that of Balbina was named for S. Mark; that of Callixtus for SS. Sixtus and Cæcilia; and that of Maximus for S. Felicitas. One characteristic of Christian epigraphy shows what a comparatively safe place the catacombs were. Inscriptions belonging to them never contain those requests to the passer to respect the tomb, which are so frequent in sepulchral inscriptions from tombs above-ground, and which sometimes, on Christian as well as pagan graves, take the form of an imprecation. An epitaph discovered by Hamilton near Eumenia, Phrygia, contains this rather violent formula: "May the passer who damages my tomb bury all his children at the same time." In another, found near the church of S. Valeria, in Milan, the imprecation runs: "May the wrath of God and of his Christ fall on the one who dares to disturb the peace of our sleep."