arker chord of cellular matter; they were of rather small diameter,
namely, 2/3000th of an inch. The two (in _L. dorsalis_) ran in a very
irregular course, not parallel to each other, making the most abrupt
bends. They passed through the membranous layers, (as seen after
dissolution,) and running for short spaces parallel to the component
laminae, were attached to them. In their irregular course, these
cement-ducts resemble those of _Pollicipes mitella_, but I could not
perceive that any cement had been poured out at the abrupt bends. In one
specimen of a basal cup, which I was enabled to examine whilst still
attached to the rock, I found under the very centre, (and of course
outside the yellow membrane,) a very small area of dark brown cement of
the usual appearance. In several specimens of full-sized cups, I was not
able to perceive any cement on the external surfaces of the upper and
later-formed layers; hence I believe that the cup is cemented to the
bottom of the hole only during the early stages of its formation; and
this, considering its protected situation, would no doubt be sufficient
to affix the animal. This probably accounts for the small size of the
cement-ducts, and for the facility with which, as it appears, the cups
can be removed in an unbroken condition from the rock. In the case,
however, of the small, flat, calcareous discs, which are formed whilst
the animal is burrowing into the rock, these are attached firmly to the
sides of the holes, in the usual manner, by cement. In this cirripede it
would be useless to look for the prehensile antennae of the larva under
the cup, for the animal, during the formation of the successive discs,
must have travelled some distance from the spot on which the larva first
attached itself.

The membrane of the peduncle is continuous with the yellow membrane
coating the external surface of the cup; and this latter membrane is
continuous with those delicate laminae which, in a calcified condition,
form the layers of the cup itself. In an exactly similar manner, in this
and other cirripedes, the membrane of the peduncle, at the top, is
continuous with that coating the valves, and is attached to the lower
exterior edge of the last-formed layer of shell. When a new shelly layer
is formed, both under the valves of the capitulum and inside the basal
calcareous cup, it projects beyond the old layer, and is included within
the old, as yet not moulted, membrane of the peduncle. Wit