h of animal
1.3; diameter of peduncle .4 of an inch.

The external membrane of the capitulum is not nearly so thick as is
usual in other Cirripedes, and is, therefore, unusually flexible. The
internal membrane, on the other hand, is very much thicker than is
usual, being only a little thinner than the outside coat; this
circumstance, as well as the similarity in colour on both sides, is
evidently due to the remarkable openness of the sack, and consequent
exposure of its inside. The inner membrane, when viewed under a high
power, is seen to be covered with the minutest spines; the external
membrane is structureless, except that there are a few rows of very
minute beads of hard chitine, like those which occur on the capitulum of
_Conchoderma aurita_. Loven, however, states that there are imbedded in
the outer membrane, scattered, minute, dendritic, calcareous particles.
Of these, I could see no trace. There is a very thin muscular layer
between the two coats, all round the capitulum, and this layer becomes
rather thicker round the base, near the peduncle. The adductor muscle,
occupying its usual place close below the mouth, is thinner than in any
other Cirripede of the same size seen by me; nor does it end so abruptly
at each extremity, as is usual: where attached to the outer coat, no
impression is left. It is a singular fact, that in this Cirripede alone,
the fibres of the adductor, and of the muscles of the cirri, and of the
trophi of the mouth, are destitute of transverse striae; but it is not
singular, that the muscles surrounding the capitulum should, also, be
destitute of striae, for this is the case with the muscles which, running
up from the peduncle, surround the capitulum in Alepas, and partly
surround it in Conchoderma. It must not be inferred from the absence of
transverse striae in the muscular fibres of the adductor and of the
cirri and trophi, that they are involuntary, but only that they are in
an embryonic condition, for I find in the natatory larva, that all the
muscles, with the exception of some connected with the eyes, are
similarly destitute, and yet perform voluntary movements.[46]

[46] Dr. C. Schmidt in his Contribution to the comparative
Anatomy of the Invertebrate animals, &c., (translated in Taylor's
Scientific Memoirs, vol. v, p. 1,) says that in young Crustacea,
"we find plain primitive fibres, which subsequently acquire the
transversely striated aspect."

Although in the d