lum
and Chthamalus,) are finely plumose. The abdomen terminates, a little
beyond the posterior end of the carapace, in a slightly upturned horny
point; a short distance anteriorly to this point, a strong, spinose,
forked projection depends from the abdominal surface.

Messrs. V. Thompson, Goodsir, and Bate, have kept alive for several days
the larvae of Lepas, Conchoderma, Balanus, Verruca, and Chthamalus, and
have described the changes which supervene between the first and third
exuviations. The most conspicuous new character is the great elongation
of the posterior point of the carapace into an almost filiform, spinose
point in Lepas, Conchoderma, Chthamalus, and Balanus, but not according
to Goodsir, in one of the species of the latter genus. The posterior
point, also, of the abdomen becomes developed in Balanus (Goodsir) into
two very long, spear-like processes, serrated on their outer sides; in
Lepas and Conchoderma, according to Thompson, into a single, tapering
spinose projection; and in Chthamalus, as figured by Mr. Bate, the
posterior bifid point, as well as the depending ventral fork, increase
much in size. Another important change, which has been particularly
attended to by Mr. Bate, is the appearance of spinose projections and
spines (some of which are thick, curved, and strongly plumose, or,
almost pectinated along their inner sides) on the pedicels and lower
segments of the shorter rami of the two posterior pairs of limbs.

The mouth in its earliest condition alone remains to be described; in
_S. vulgare_, it is seated on a very slight prominence, in a most
remarkable situation, namely, in a central point between the bases of
the three pairs of legs. I traced by dissection the oesophagus for some
little way, until lost in the cellular and oily matter filling the whole
animal, and it was directed anteriorly, which is the direction that
might have been expected, from the course followed by the oesophagus in
the larva in the last stage, and in mature Cirripedes. Mr. A. Hancock
has called my attention to a probosciformed projection on the under side
of the larva of _Lepas fascicularis_, when just escaped from the egg.
Mr. Bate has described this same proboscis in Balanus and Chthamalus,
and states the important fact, that it is capable of being moved by the
animal; and, lastly, I have seen it in an Australian Chthamalus, and in
Ibla, of remarkable size. This proboscis, which is always directed
posteriorly, (l