Fig. 16.—Gallery in St. Hermes.
Many of these arenaria may be observed excavated in the hill-sides near Rome; but except when incidentally forming part of a Catacomb, they have never been found to contain a single grave. Indeed, in consequence of the utter unfitness of the pozzolana for the
purposes of Christian sepulture, the intrusion of a deposit of that material into the area of a Catacomb prevented the extension or necessitated the diversion of its galleries. Moreover, where the attempt has been made to convert an arenarium into a Christian cemetery, the changes which have been made show conclusively its original unfitness for the latter purpose. The accompanying section of a gallery in the Catacomb of St. Hermes will exhibit the structural additions necessary to adopt an arenarium for Christian sepulture. The sides of the semi-eliptical vault had to be built up with brick-work, leaving only a narrow passage in the middle. The loculi were spaces left in the masonry, in which the mouldering skeletons may still be seen. The openings were closed with slabs in the usual manner, as shown in the elevation, ([Fig. 17],) except at the top, where they cover the grave obliquely, like the roof of a house. The vault is often arched with brick-work, and at the
intersection of the galleries has sometimes to be supported by a solid pier of masonry. In part of an ancient arenarium converted into a cemetery in the Catacomb of St. Priscilla similar constructions may be seen. The long walls and numerous pillars of brick-work concealing and sustaining the tufa, and the irregular windings of the passages, show at once the vast difference between the arenarium and the Catacomb, and the immense labour and expense required to convert the former into the latter.
Fig. 17.—Part of Wall of Gallery in St. Hermes.
It has been urged in objection to this theory, that the difficulty of secretly disposing of at least a hundred millions of cubic feet of refuse material taken from the Catacombs must have been exceedingly great, unless it could be removed under cover of employment for some economic purpose. It will be shown, however, that secrecy was not always necessary, as has been assumed, but that, on the contrary, the Christian right of sepulture was for a long time legally recognized by the Pagan Emperors; and that the Catacombs continued to be publicly used for a considerable time after the establishment of Christianity on the throne of the Cæsars. During the exacerbations of persecution there is evidence that the excavated material was deposited in the galeries already filled with graves, or, as we have seen, in the spacious vaults of adjacent arenaria. If the Catacombs were merely excavations for sand or stone, as has been asserted, we ought to find many of their narrow galleries destitute of tombs, and many of the arenaria containing them; whereas every yard of the former is occupied with graves, and not a single grave is found in the latter, nor do they contain a single example of a mural painting or inscription. The conclusion is irresistible that the Catacombs proper were created exclusively
for the purpose of Christian burial, and in no case were of Pagan construction.
The erroneous theory here combated has arisen, as we have said, chiefly from certain classical allusions to the arenaria, and from passages in the ancient ecclesiastical records describing the burial places of the martyrs, as in cryptis arenariis, in arenario, or ad arenas. Some of these localities, however, have been identified beyond question, and found to consist merely of a sandy kind of rock, and not at all of the true pozzolana. In others a vein of pozzolana does actually occur in the Catacombs, or they are connected with ancient arenaria, as at St. Agnes and at Calixtus. In the other instances the localities are either yet unrecognized, or the expression merely implies that the cemetery was near the sand pits—juxta arenarium, or in loco qui dicitur ad Arenas.