body. The thorax, on
the dorsal and ventral surfaces, is well furnished with straight and
oblique muscles (without striae), which straighten and curl up this part
of the body. The muscles running into the pedicels of the cirri, cross
each other on the ventral surface of the thorax; the muscles within the
rami are attached to the upper segments of the pedicels. Finally, I may
remark that the whole of the body and the cirri are capable of many
diversified movements.

_Mouth._--This is prominent, and almost probosciformed (Pl. IX, fig. 4
_b_), and in the abnormal Anelasma (Pl. IV, fig. 2 _d_), quite
probosciformed,--such, also, was its character in the larval condition.
In outline, it is either sub-triangular, or oval with the longer axis
transverse; the whole is capable, as well as the separate organs, of
considerable movement, as I have seen in living sessile Cirripedes. It
is composed (Tab. V, fig. 2) of a labrum, swollen or bullate, often to
such an extent as to equal in its longitudinal axis the rest of the
mouth; of palpi soldered to the labrum; of mandibles, maxillae, and outer
maxillae, the latter serving as a lower lip. These organs have only their
upper segments free, but there are traces, clearly seen in the mandibles
(Pl. X, fig. 1, _a_, _b_), of their being formed of three segments. The
two lower segments are laterally united, and open into each other, the
prominence of the mouth being thus caused: this condition appears to me
curious, and is, to a certain limited extent, intermediate between those
articulated animals which have their trophi soldered into a proboscis,
and those furnished with entirely free masticatory or prehensile organs.
The palpi adhere to the corners of the labrum; and I call them palpi
only from seeing that they spring laterally from above the upper
articulation of the mandibles. The prominence of the mouth, measured
from the basal fold by which the whole is separated from the body, is
much greater on the half formed by the labrum and mandibles, than on the
other half facing the cirri. The trophi surround a cavity--the
supra-oesophageal cavity--in the middle of which, between the mandibles
is seated the orifice of the oesophagus. The oesophagus is surrounded by
long, fine, muscular fasciae, radiating in all directions, opposing the
constrictor muscles, and is capable of violent swallowing
movements,--constriction after constriction being seen to run down its
whole course: there are also