The sides of the galleries contain several rows of loculi, sometimes six or eight. Some bodies are buried under the floor, or in the cubiculi which open right and left at short intervals. Assuming these galleries to be capable of containing two bodies per metre, the number of Christians buried in the catacombs, within three miles from the gates of Servius, may be estimated at a minimum of 1,752,000. The construction of this prodigious labyrinth required the excavation and removal of 96,000,000 cubic feet of solid rock. With regard to the number of inscriptions, I quote the following passage from Northcote's "Epitaphs," page 3: "Of Christian inscriptions in Rome, during the first six centuries, de Rossi has studied more than fifteen thousand, the immense majority of which were taken from the catacombs; and he tells us there is still an average yearly addition of about five hundred, derived from the same source. This number, vast as it is, is but a poor remnant of what once existed. From the collections made in the eighth and ninth centuries it appears that there were once at least one hundred and seventy ancient Christian inscriptions in Rome, which had an historical or monumental character; written generally in metre, and to be seen at that time in the places which they were intended to illustrate. Of these only twenty-six remain, either whole or in parts. In the Roman topographies of the seventh century, one hundred and forty sepulchres of famous martyrs and confessors are enumerated; we have recovered only twenty inscribed memorials, to assist us in the identification of these. Only nine epitaphs have come to light belonging to the bishops of Rome during the same six centuries; and yet, during that period, there were certainly buried in the suburbs of the city upwards of sixty. Thus, whatever facts we take as the basis of our calculation, it would seem that scarcely a seventh part of the original wealth of the Roman church in memorials of this kind has survived the wreck of ages; and de Rossi gives it as his conviction that there were once _more than one hundred thousand_ of them."