successive
layers, and closely resemble in shape the scuta of the _Conchoderma
aurita_. The orifice in _A. tubulosa_ projects so much as to be almost
tubular. In _A. parasita_ and _A. minuta_ it does not project, and is
either moderately large, or very small in proportion to the length of
the capitulum; from contraction it is much wrinkled. The membrane
forming the capitulum is smooth and very transparent; it contains very
few tubuli, except under certain irregular projections in _A. cornuta_.

The _Peduncle_ is rather short and narrow; it blends into the capitulum,
and is not, in some of the species, separated from it by any distinct
line; the surface of attachment is rather wide. Within the peduncle we
have the three usual layers of striae-less muscles; namely, the innermost
and longitudinal, which run lower down than the others; the middle and
transverse; and, lastly, the exterior, oblique muscles, which cross each
other (becoming transparent) on the rostral central line. These several
muscles run up from the peduncle and surround the capitulum; from the
transparency of the membranes they can be seen from the outside: they
are particularly conspicuous round the orifice, which they probably
serve to close. There is, in all cases, the usual adductor scutorum
muscle (with transverse striae), which is attached under the horny scuta,
where such exist. The fact of the striae-less muscles of the peduncle
surrounding the whole capitulum, has been observed only in one other
genus, namely Anelasma. In consequence of this structure, the capitulum
must possess considerable powers of contraction.

The antennae of the larva in the _Alepas cornuta_ and _A. minuta_ have
the sucking disc nearly circular, with the spines unusually plain on the
distal as well as proximal margin. Basal segment broad, much constricted
where united to the disc. The ultimate segment has on the middle of the
outer margin, in _A. cornuta_, two minute spines, which I have not
observed in any other cirripede: on the summit there are the usual
spines.

_Size._--Three of the species are small.

_Filamentary Appendages._--These are rather small; there is only one on
each side, situated on the posterior margin of a slight swelling,
beneath the basal articulation of the first cirrus; and therefore in the
position in which the filaments are most constant in Lepas, and where
they likewise occur in Conchoderma.

_Body._--The prosoma is either pretty well develope