furnished with graves around their sides,--the burial-place arranged
beforehand for some large family, or for certain persons buried with
special honor. Other openings in the rock are designed for chapels, in
which the burial and other services of the Church were performed. These,
too, are of various sizes and forms; the largest of them would hold but
a small number of persons;[F] but not unfrequently two stand opposite
each other on the passage-way, as if one were for the men and the other
for the women who should be present at the services. Entering the chapel
through a narrow door whose threshold is on a level with the path, we
see at the opposite side a recess sunk in the rock, often semicircular,
like the apsis of a church, and in this recess an _arcosolium_,--which
served at the same time as the grave of a martyr and as the altar of the
little chapel. It seems, indeed, as if in many cases the chapel had been
formed not so much for the general purpose of holding religious service
within the catacombs, as for that of celebrating worship over the
remains of the martyr whose body had been transferred from its original
grave to this new tomb. It was thus that the custom, still prevalent
in the Roman Church, of requiring that some relics shall be contained
within an altar before it is held to be consecrated, probably began.
Perhaps it was with some reference to that portion of the Apocalypse in
which St. John says, "I saw under the altar the souls of them that were
slain for the word of God, and for the testimony which they held. And
they cried with a loud voice, saying, How long, O Lord, holy and true,
dost thou not judge and avenge our blood on them that dwell on the
earth? And white robes were given unto every one of them; and it was
said unto them, that they should rest yet for a little season, until
their fellow-servants also and their brethren that should be killed as
they were should be fulfilled."[G] At any rate, these words must have
dwelt in the memories of the Christians who came to worship God in the
presence of the dead by whom they were surrounded in the catacombs. But