andibles have their
second and third teeth nearly equal in size to the first, and they do
not appear pectinated: the maxillae have their spinose edge very nearly
straight: the outer maxillae are pointed. The olfactory orifices are
similarly situated, and of similar shape; they are dark coloured.

_Cirri._--These also are similar to those of _I. Cumingii_; the
segments, however, of the three posterior cirri have each four pair of
spines, placed very close together in a transverse direction. First
cirrus has its two rami unequal in length by about six segments. The
anterior rami of the second and third cirri are thicker, and more
thickly clothed with spines, than the posterior rami, to perhaps a
greater degree than in _I. Cumingii_. In the posterior cirri, the upper
segments of the pedicels are nearly as long as the lower segments.

_Caudal Appendages_, four times as long as the pedicel of the sixth
cirrus, and three fourths of the length of the rami of this same cirrus:
segments thirty-two in number, and therefore as many as those forming
the sixth cirrus: the upper segments are much thinner and longer than
the basal segments; each furnished with a circle of short bristles;
whole appendage excessively thin and tapering: the two closely
approximate.

_Colour._--From some well-preserved dryed specimens in Mr. Stutchbury's
possession, it appears that the sack, cirri and trophi, were dark blue,
as in _I. Cumingii_; after being long kept in spirits, these parts
become brown.

_Generative System._--The penis (Pl. IV, fig. 9 _a_) is very singular in
structure; it is of the ordinary length, but of small diameter; it
tapers but little; it consists of a moveable articulated, and a fixed
unarticulated portion; this latter is smooth, much flattened, not
divided into segments, and projects straight out under the caudal
appendages; it is about one third of the length of the entire penis; it
corresponds with a part present in all Cirripedes, but here surprisingly
elongated. The articulated portion consists of separate segments, twenty
in number, quite as distinct as those of the cirri; each one is oblong,
being longer by about a third part than broad; each has a few short
bristles round its upper margin; the terminal segment has a circular
brush of bristles. The vesiculae seminales are easily seen, though they
are narrow; they are slightly tortuous; they enter the prosoma, and lie
on each side of the stomach; their outer case has a