the
thorax, corresponding with the interspaces between the five transverse
articulations, there are four pair of short limbs, but their bases, I
believe, are prolonged across the inner or ventral surface of the
thorax, so as almost to touch each other. These limbs, I believe, have
no articulations, except, perhaps, where united to the thorax. The
anterior or lowest limb, on each side, supports two or sometimes only a
single spine; this pair is rather smaller than the second, and is placed
a little more distant from it, than are the upper pairs from each other.
The second pair differs from the upper two, only in having its three
spines a very little shorter. The two upper or posterior pair exactly
resemble each other; each has two spines on the summit, and a third
seated lower down, on a little notch on the outer side, but with its
point on a level with the others. The points of the spines of the two
upper limbs, stand on a level with the external spines at the end of the
abdomen. All the spines are of excessive tenuity and sharpness; they are
straight, long, and not plumose.

The abdominal lobe is square, and from not being wrinkled, has a
different appearance from the thorax: on each of the posterior angles,
there are three moderately long, very sharp spines, with the tips of the
outer pair bent a little inwards; in the middle between them, there are
two little spines, and a little below and outside these latter, on the
ventral surface, there are two other longer spines with their tips bent
inwards; and again, lower down, two other pair, one beneath the other,
of short spines. Perhaps, the three pair of spines on the ventral
surface, mark the three segments, which are distinct on the abdomen of
the larva in the last stage of its development, in Lepas and other
genera. In the same way, it is probable that the lateral spine on the
notch in each limb, marks the point where, in the larva, there is an
articulation. Altogether, there are seven pairs of spines on the
abdomen, and eleven pairs on the thoracic limbs.

A little way beneath the lower or anterior pair of limbs, the thorax is
abruptly bent, and becomes confluent with the lower internal parts of
the whole animal. Here, the very delicate membrane of chitine which
lines the sack or tube, extending from the external orifice, can be seen
to be continuous, as in all Cirripedes, with the outer tunic of the
thorax. Within the thorax, there are some longitudinal muscles, w