pulchella_, they are very
small compared with the valves of the capitulum. When the scales are
symmetrical, new ones are first formed only round the summit of the
peduncle, and only those in the few uppermost whorls continue to grow or
to be added to at their bases; afterwards membrane is deposited under
them. The shelly matter of the scales resembles that of the valves, and
the manner of growth is the same; tubuli generally run to and through
them from the corium. From the continued enlargement of the membrane of
the peduncle, the scales come to stand, in the lower portion, some way
apart. In Ibla, new horny styles are formed indifferently in all parts
of the peduncle. In some species of Pollicipes, the calcareous styles
are not symmetrical or symmetrically arranged; and besides those first
formed round the top of the peduncle, there are other and larger ones
formed near its base. Lastly, in Lithotrya we have a row of calcareous
discs or an irregular, basal cup, formed in the same manner as the
valves of the capitulum: in this genus alone (as already stated,) the
calcified scales are moulted, and here alone their edges are serrated.

The peduncle is lined within by three layers of muscles, longitudinal,
transverse, and oblique, all destitute of the transverse striae,
characteristic of voluntary muscles; they run from the bottom of the
peduncle to the base of the capitulum, as in Lepas, or half way up it,
as in Conchoderma; in Alepas alone they surround the whole capitulum up
to its summit. In Lithotrya there are two little, fan-like, transverse
muscles (involuntary), extending from the basal points of the terga to a
central line on the under side of the carina. The gentle swaying
to and fro movements, and the great power of longitudinal
contraction,--movements apparently common, as I infer from facts
communicated to me by Mr. Peach, to all the Pedunculata,--are produced
by these muscles. The interior of the peduncle is filled up with a great
mass of branching ovarian tubes; but in Ibla and Lithotrya, the upper
part of the peduncle is occupied by the animal's body.

_Means of Attachment._--If the peduncle be very carefully removed (Tab.
IX, fig. 7 and Tab. I, fig. 6 _b_), from the surface of attachment,
quite close to the end, but not at the actual apex, the larval
prehensile antennae can always be found: these have been sufficiently
described for our present purpose under the head of the Metamorphoses;
but I may add,