presence of the dead by whom they were surrounded in the catacombs. But they knelt before the altar-tombs, not as before altars consecrated with relics of saints, but as before altars dedicated to God and connected with the memory of their own honored and beloved dead, whom he had called from them into his holy presence. [Footnote F: These chapels are generally about ten feet square. Some are larger, and a few smaller than this.] [Footnote G: Revelations, vi. 9-11. It seems probable that another custom of the Roman Church took its rise in the catacombs,--that of burning candles on the altar; a custom simple in its origin, now turned into a form of superstition, and often abused to the profit of priests.] It is impossible to ascertain the date at which these chapels were first made; probably some time about the middle of the second century they became common. In many of the catacombs they are very numerous, and it is in them that the chief ornaments and decorations, and the paintings which give to the catacombs an especial value and importance in the history of Art, and which are among the most interesting illustrations of the state of religious feeling and belief in the early centuries, are found. Some of the chapels are known to be of comparatively late date, of the fourth and perhaps of the fifth century. In several even of earlier construction is found, in addition to the altar, a niche cut out in the rock, or a ledge projecting from it, which seems to have been intended to serve the place of the credence table, for holding the articles used in the service of the altar, and at a later period for receiving the elements before they were handed to the priest for consecration. The earliest services in the catacombs were undoubtedly those connected with the communion of the Lord's Supper. The mystery of the mass and the puzzles of transubstantiation had not yet been introduced among the believers; but all who had received baptism as followers of Christ, all save those who had fallen away into open and manifest sin, were admitted to partake of the Lord's Supper. Possibly upon some occasions these chapels may have been filled with the sounds of exhortation and lamentation. In the legends of the Roman Church we read of large numbers of Christians being buried alive, in time of persecution, in these underground chambers where they had assembled for worship and for counsel. But we are not aware of any proof of the truth of these stories having been discovered in recent times. This, and many other questionable points in the history and in the uses of the catacombs, may be solved by the investigations which are now proceeding; and it is fortunate for the interests, not only of truth, but of religion, that so learned and so honest-minded a man as the Cavaliere de Rossi should have the direction of these explorations.