the different parts or ornamented the entrances. In one instance, indeed in the chief basilica yet discovered in the cemetery of Callistus, there is a chamber without any altar, communicating with the church by means of a funnel-shaped opening, piercing the earthen wall, here some twelve feet thick, and entering the chamber, which is at a lower level, at the height of five or six feet, in a slanting direction; so that all that was spoken in the church could be heard, yet nothing that was done there could be seen, by those assembled in the chamber. This is very naturally supposed to have been the place reserved for the class of public penitents called _audientes_ or hearers, and for the catechumens, not yet initiated by baptism. [Illustration: PLAN OF SUBTERRANEAN CHURCH IN THE CEMETERY OF ST. AGNES. A. Choir, or chancel, with episcopal chair (_a_) and benches for the clergy (_b b_). 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. [Illustration: A _Cathedra_ or Episcopal Chair in the Catacomb of Saint Agnes.]