xternal opening being minute, and
gradually increasing downwards. At the bottom of the cavities, many
shells are still found, notwithstanding the great numbers that have been
taken out by visitors; in many the valves of a species of arca, an
animal which conceals itself in small hollows, occur. The perforations
are so considerable in depth and size, that they manifest a
long-continued abode of the lithodomi in the columns, for, as the
inhabitant grows older and increases in size, it bores a larger cavity,
to correspond with the increased magnitude of its shell. We must,
consequently, infer a long-continued immersion of the pillars in
sea-water, at a time when the lower part was covered up and protected by
marine, fresh-water, and volcanic strata, afterwards to be described,
and by the rubbish of buildings; the highest part, at the same time,
projecting above the waters, and being consequently weathered, but not
materially injured. (See fig. 90, p. 514.)

On the pavement of the temple lie some columns of marble, which are also
perforated in certain parts; one, for example, to the length of eight
feet, while, for the length of four feet, it is uninjured. Several of
these broken columns are eaten into, not only on the exterior, but on
the cross fracture, and, on some of them, other marine animals (serpulae,
&c.) have fixed themselves.[719] All the granite pillars are untouched
by lithodomi. The platform of the temple, which is not perfectly even,
was, when I visited it in 1828, about one foot below high-water mark
(for there are small tides in the bay of Naples); and the sea, which was
only one hundred feet distant, soaked through the intervening soil. The
upper part of the perforations, therefore, were at least twenty-three
feet above high-water mark; and it is clear that the columns must have
continued for a long time in an erect position, immersed in salt water,
and then the submerged portion must have been upraised to the height of
about twenty-three feet above the level of the sea.

By excavations carried on in 1828, below the marble pavement on which
the columns stand, another costly pavement of mosaic was found, at the
depth of about five feet below the upper one (_a_, _b_, fig. 90). The
existence of these two pavements, at different levels, clearly implies
some subsidence previously to the building of the more modern temple
which had rendered it necessary to construct the new floor at a higher
level.

[Illustrat