ssible, the cement is poured out through a
straight row of orifices along the rostral edge, thus causing, by an
excellent adaptation, a narrow margin to adhere firmly to the thin and
cylindrical branches of the coralline. These orifices are represented,
magnified seven times, in Pl. IX, fig. 7, in which the lower attached
portion of the peduncle is split open and exhibited; they are circular,
and stand at regular intervals, in a straight line; the higher orifices
are larger, but further apart from each other than the lower ones; in
one full-grown specimen, I counted ten of these orifices in a length of
exactly a quarter of an inch. At each period of growth, the corium
recedes a little from the attached portion of the peduncle; of which
portion, the greater part is thus left empty and as incapable of further
growth, as are the larval antennae at the extreme point: in the specimen
figured, the corium extended a little below the upper orifice. The
prehensile antennae, however, I must remark, do not strictly rise from
the extreme point of the peduncle, but at a little distance from it, on
the rostral surface; this simply ensues from the antennae in the larva,
being situated on the sternal surface, close to, but not actually on the
front of the head. The two cement glands are seated high up on the sides
of the peduncle, and remote from each other; they are small, unusually
globular and transparent. The two cement-ducts (fig. 7 _a_ _a_)
proceeding from them, are 3/2000ths of an inch in diameter, and run in a
zig-zag line; at the point where they pass through the corium to enter
the lower attached portion of the peduncle, they become closely
approximated, and partially imbedded in the membrane of the peduncle.
Together they run along the rostral edge, giving out through each
orifice a little disc of brownish cement, and finally they enter the
larval antennae. The peduncle, just above the attached portion, where
still lined by corium, no doubt increases in diameter at each period of
growth, and must, I presume, become pressed against the almost parallel
branch of the coralline. The corium, at this same period, shrinks, or is
absorbed, and the two cement-ducts come in contact with, and adhere to,
the inner surface of the outer membrane of the peduncle; and then, by a
process which I do not understand in this or any other Cirripede,
apertures are formed both in the ducts and through the membrane, so that
the cement passes through,