r than the mandibles; the spinose
edge being only the 1/100th of an inch in length; the edge, instead of
being square, and furnished with a double row of long spines, as in all
other Cirripedes, is rounded, thick, club-shaped, and with the side
facing the mandibles, thinly and irregularly strewed with short, thick,
very minute spines; there is a large broad apodeme (_a_), in the usual
place, but it is much more transparent and flexible than common: there
are also the usual muscles. In other cirripedes, the mandibles alone
seem to force the prey down the oesophagus; but here, the mandibles and
maxillae equally stand over the orifice, and their adjoining spinose
faces and edges, seem excellently adapted to force, by their united
action, any minute living creature down the passage.

The _Outer Maxillae_ are almost in as rudimentary a condition as the
palpi; they are quite spineless; viewed externally, they appear like two
smooth, blunt, very minute projecting points; but viewed internally, the
membrane forming the supra-oesophageal hollow seems to be united
actually to their tips, so that they do not project at all. I was
surprised to find that the longitudinal muscles going to these organs
were developed, in proportion to the other muscles, quite as fully as in
ordinary cirripedes: hence, these two little outer maxillae, no doubt,
serve as an under lip, and possess the usual backward and forward
movement.

The surface of the probosciformed mouth facing the first pair of cirri,
has a deep central longitudinal fold, and rather more than half-way
down, a transverse fold; just above this latter fold, and therefore
quite below the outer maxillae themselves, the two olfactory orifices are
seated; these are unusually large, and the sack into which they lead, is
most unusually large and deep. In this Cirripede, I was first enabled to
observe that the membrane lining the sack is tubular, and open at the
bottom.

_Cirri._--There are, as usual, six pair, and not of very small size;
they have a shapeless and rudimentary appearance; they are coloured,
like the rest of the body, blackish purple: they are quite spineless,
and not articulated, but their anterior faces are either obscurely or
very plainly lobed, so that in some (for instance in the third pair, Pl.
IV, fig. 6), nine or ten prominent steps could be counted, manifestly
representing so many segments. The rami are equal in length in the first
pair, and slightly unequal in t