rmed by
the backward production of the carapace, does not require any
discussion. The valves have no homological signification.

[12] This distinguished naturalist has given his opinion in the
'American Journal of Science,' March, 1846, that "the pedicel of
Anatifa corresponds to a pair of antennae in the young;" although
the peduncle or pedicel is undoubtedly thus terminated, even in
mature individuals, I think it has been shown that it is the
whole of the anterior part of the larva in front of the mouth,
which is directly converted into the peduncle. Professor E.
Forbes, in his Lectures, and Professor Steenstrup, in his
'Untersuchungen ueber das vorkommen des Hermaphroditismus in der
Natur,' ch. v, have considered the peduncle as a pair of fused
legs. Loven has taken, judging from a single sentence, the same
view of the homologies of the external parts as I have done; in
his description of _Alepas squalicola_, (Ofversigt of Kongl.
Vetens., &c., Stockholm, 1844, pp. 192-4), he uses the following
words: "Capitis reliquae partes, ut in Lepadibus semper, in
_pedunculum mutatae et involucrum_," &c.; his involucrum is the
same as the capitulum of this work.

As we have just seen that the first pair of natatory legs is borne on
the ninth segment of the body, so it must be with the first pair of
cirri, which consequently correspond to the outer maxillipods (the two
inner pair of maxillipods or pied-machoires being here aborted) of the
higher Crustacea, and hence their difference from the five posterior
pair, which correspond with the five, ordinary pair of ambulatory legs
in these same Crustacea. The part of the body, which I have called the
prosoma, that is the protuberant, non-articulated, lower part of the
thorax (Pl. IX, fig. 4 _n_), is a special development, either of the
ninth segment, bearing the first pair of cirri, or of the segments
corresponding with the organs of the mouth. The three abdominal segments
of the larva are represented in the mature Cirripede, in the Order
containing the Lepadidae, only by a minute, triangular gusset, let in
between the V-shaped tergal arches of the last thoracic segment: in this
gusset, small as it is, is seated the anus, and on each side the caudal
appendages, often rudimentary and sometimes absent. In another order, I
may remark, (including, probably, the Alcippe of Mr. Hancock,) the
cirri, of which there are only three pair, are