The two arch-cemeteries are those of Callistus on the Via Appia and Priscilla on the Salaria. They are arch-cemeteries because their origin and the part they played in the early years of Roman Christianity gave them a pre-eminent importance, and having been bestowed upon the Church by their owners they became the official catacombs of the Christian community. Each bears in its bosom the record of the first Roman converts; each is rich in frescoes and inscriptions; each bears testimony to the fact that from the beginning the Roman Christians counted among them many of patrician and senatorial rank; we meet with the names of the _Aurelii_, _Caecilii_, _Maximi Caecilii_, of _Praetextatus Caecilianus_ and _Pomponius Grecinus_, and of _Cornelius_, the first bishop to belong to a Roman _gens_, in the catacomb of Callistus; and with those of the _Prisci_, _Ulpii_, and _Acilii Glabriones_ in that of Priscilla. Priscilla, with her son the Senator Pudens, is the reputed hostess of Peter on his visit to Rome, and in the catacomb which bears her name there occurs repeatedly the Apostle's name--unknown in classical nomenclature--both in its Greek and Latin forms, _Petros_, _Petrus_. It is a region of this catacomb which preserves the tradition of the _Fons sancti Petri_, "the well or font of S. Peter," "the cemetery where Peter baptized" or "where Peter first sat," still unconsciously recorded in the Roman feast of "the Chair of S. Peter" on January 18. Here too was buried the philosopher Justin, martyred under Aurelius in A.D. 165, who lived in the house of Pudens, and here, when Justin was describing the rite itself in his Apology to the emperors, was frescoed the earliest representation of the solemn moment of the breaking of bread at the Eucharist. The mystical number of the guests, seven, the fish on the table, archaic symbol of Christ, the "seven baskets full" in allusion to the miracle of the loaves, and the fact that the _agape_ was already dissociated from the Eucharist in the time of Justin, mark this out as a typical example of that symbolical treatment of real events which is characteristic of early Christian art. The celebrant stands at one corner of the crescent-shaped table breaking the bread; five men and women sit at the table, the only other standing figure being that of a woman wearing the Jewish married woman's bonnet, filling, apparently, the office of _vidua_ or woman-elder. The catacomb of Callistus--an agglomeration of separate _hypogaea_, which originated in the _crypts of Lucina_ and the cemetery of those _Caecilii_ who were among the earliest Roman families to embrace Christianity--is no less interesting.