ir apices
generally worn and truncated. Viewed internally (fig. 3 _b'_), whilst
the valves are in their proper places, the inner and growing surfaces of
the smallest are seen to be triangular,--of the larger, some are
rhomboidal, and others quadrilateral with the upper side much longer
than the lower. These latter valves overlap the upper parts of the
little valves on both sides of them; the rhomboidal valves overlap a
valve on one side, and are overlapped on the other; the triangular
valves are overlapped on both sides.

The corium lining the capitulum is produced into narrow purple crests,
which enter the interstices between the valves, more especially along
the line separating the upper and lower whorls. There is, also, a
distinct flattened, tapering, free projection of corium, which enters
between the carina and sub-carina; and another between the rostrum and
sub-rostrum.

_Peduncle_, much compressed, short, rarely as long as the capitulum; in
one very large specimen it was extremely short, barely one fifth of the
length of the capitulum. The attached portion, which is moderately
pointed in young specimens, becomes extremely broad in old specimens.
The calcified scales sometimes differ a little in size, in specimens of
the same age: they are always compactly and symmetrically arranged: in
old specimens they are much larger than in young ones: each scale has,
at first, a transversely elliptic growing base, which ultimately becomes
nearly circular. Exteriorly the tips of the scales are always
disintegrated; they are sometimes club-shaped, owing to the scales
having been re-added to after a period of reduced growth. The scales are
fringed with brown disintegrating membrane.

_Attachment._--At the base of the peduncle, the two cement-ducts running
together, twist about in a singular manner, and at their bends pour
forth cement. According to the age of the specimen, the ducts vary in
diameter from 1/2000th to 5/2000ths of an inch. The two cement glands
are small and difficult to find; they are retort-shaped, with two
ovarian tubes entering each. They lie close together, in nearly the
centre of the peduncle, and less than half-way down it. This proximity
of the two cement-glands, and their position low down the peduncle, are
of interest in relation to the position of these same glands in the
sessile Cirripedes.

_Size and Colours._--This is the largest and most massive species in the
family. I have seen one specimen