B. Division for the men, separated from the choir by two pillars, supporting an arch.

C. Corridor of the catacomb, affording entrance to the church.

D. Division for the women, with a tomb in it.

Each portion is subdivided by projections in the wall.

The basilica, in which the Christians were assembled, when Sebastian sent his message, was like the one discovered in the cemetery of St. Agnes. Each of the two divisions was double, that is, consisted of two large chambers, slightly separated by half-columns, in what we may call the women’s church, and by flat pilasters in the men’s, one of these surfaces having in it a small niche for an image or lamp. But the most remarkable feature of this basilica is a further prolongation of the structure, so as to give it a chancel or presbytery. This is about the size of half each other division, from which it is separated by two columns against the wall, as well as by its lesser height, after the manner of modern chancels. For while each portion of each division has first a lofty-arched tomb in its wall, and four or five tiers of graves above it, the elevation of the chancel is not much greater than that of those arcosolia or altar-tombs. At the end of the chancel, against the middle of the wall, is a chair with back and arms cut out of the solid stone, and from each side proceeds a stone bench, which thus occupies the end and two sides of the chancel. As the table of the arched-tomb behind the chair is higher than the back of the throne, and as this is immovable, it is clear that the divine mysteries could not have been celebrated upon it. A portable altar must, therefore, have been placed before the throne, in an isolated position in the middle of the sanctuary: and this, tradition tell us, was the wooden altar of St. Peter.

A Cathedra or Episcopal Chair in the Catacomb of Saint Agnes.

We have thus the exact arrangements to be found in the churches built after the peace, and yet to be seen in all the ancient basilicas in Rome—the episcopal chair in the centre of the apse, the presbytery or seat for the clergy on either hand, and the altar between the throne and the people. The early Christians thus anticipated underground, or rather gave the principles which directed, the forms of ecclesiastical architecture.

It was in such a basilica, then, that we are to imagine the faithful assembled, when Corvinus and his satellites arrived at the entrance of the cemetery. This was the way which Torquatus knew, leading down by steps from a half-ruinous building, choked up with faggots. They found the coast clear, and immediately made their arrangements. Fulvius, with one body of ten or twelve men, lurked to guard the entrance, and seize all who attempted to come out or go in. Corvinus, with Torquatus and a smaller body of eight, prepared to descend.

“I don’t like this underground work,” said an old, grey-bearded legionary. “I am a soldier, and not a rat-catcher. Bring me my man into the light of day, and I will fight him hand to hand, and foot to foot; but I have no love for being stifled or poisoned, like vermin in a drain.”