rt of the peduncle is internally filled by cement, and thus
rendered rigid. In _Lepas fascicularis_ a vesicular ball of cement
surrounding the peduncle is thus formed (Pl. I, fig. 6), and serves as a
float! All these curious, special adaptations are described under the
respective genera. How the cement forces its way through the antennae,
and often through apertures in the thick membrane of the peduncle, I do
not understand. I do not believe, though some appearances favoured the
notion, that the duct itself debouches and divides, at least this is not
the case in Coronula, but only that the internal chord of cellular
matter thus acts and spreads itself out; nor do I understand how, when
the antennae and immediately adjoining parts are once cemented down, any
more cement can escape; yet this must take place, as may be inferred
from the breadth of the cemented, terminal portion of the peduncle in
Lepas and Conchoderma; and from the often active condition in old
individuals of the cementing organs.

I have entered on this subject at some length, (and I wish I had space
for more illustrations,) from its offering, perhaps, the most curious
point in the natural history of the Cirripedia. It is the one chief
character of the Sub-class. I am well aware how extremely improbable it
must appear, that part of an ovarian tube should be converted into a
gland, in which cellular matter is modified, so that instead of aiding
in the development of new beings, it forms itself into a tissue or
substance, which leaves the body[15] in order to fasten it to a foreign
support. But on no other view can the structure, clearly seen by me both
in the mature Cirripede and in the larva, be explained, and I feel no
hesitation in advancing it. I may here venture to quote the substance of
a remark made by Professor Owen, when I communicated to him the
foregoing facts, namely, that there was a new problem to solve,--new
work to perform,--to attach permanently a crustacean to a foreign body;
and that hence no one could, _a priori_, tell by what singular and novel
means this would be effected.

[15] The protrusion of the egg-bearing pouches in Cyclops and its
kindred genera, outside the body, offers a feeble analogy with
what takes place in Cirripedes. Professor Allman ('Annals of
Natural History,' vol. xx, p. 7,) who has attended to the
subject, says that the external egg-bearing pouches are "a
portion of the membrane of the true ovari