air, and this is the case with
those within the lateral horns.

_Larva in the Second Stage._--Notwithstanding the considerable changes,
already briefly given, which the larva undergoes during the first two or
three exuviations after leaving the egg, all these forms may be
conveniently classed under the first stage. The larva in the Second
stage is known only from a single specimen described, figured, and found
by Burmeister,[8] adhering to sea-weed in the midst of other larvae of
Lepas in the last stage. In its general shape and compressed form, it
seems to come nearer to the last than to the first stage. It has only
three pair of legs, situated much more posteriorly on the body than in
the first stage, and all directed posteriorly; they are much shorter
than heretofore, and resemble rather closely those of the last stage,
with the important exception that the first pair has only one ramus. It
is this circumstance which leaves no doubt on my mind, that we here have
the three pair of limbs, of the first stage, metamorphosed. The body is
prolonged some way behind these limbs, and ends in a blunt, rounded
point, in which, probably, are developed the three posterior pair of
legs and the abdomen of the larva in the last stage. The mouth is now
seated some way anteriorly to the limbs, is large and probosciformed,
and is, I presume, still destitute of trophi. There are now two closely
approximate eyes, but as yet both are _simple_. The smaller pair of
antennae has disappeared. The whole animal was attached to the sea-weed
by a (I presume, pair of,) "fleischigen Fortsatz," which Burmeister
considers as the prehensile antennae, to be presently described, in an
early state of development. I have little doubt that this is correct,
for in an abnormal Cirripede of another order, in which the larva
appears in the _first_ stage with prehensile antennae, the eggs have two
great projecting horns including these organs, and attached by their
tips, through some unknown means, to the sack of the parent, apparently
in the same manner as Burmeister's larva was attached to the sea-weed. I
will only further remark on the larva of this Second stage, that its
chief development since the first stage, has been towards its anterior
end. The next great development, to be immediately described, is towards
the posterior end of the animal.

[8] Beitraege zur Naturgeschichte der Rankenfuesser, s. 16, Tab. i,
figs. 3, 4.

_Larva, Last Stage._--M