the
cirri increases with the age of the specimen; but that the
relative numbers in the different cirri keep, as far as I have
seen, nearly constant; hence the numbers are often given in
the descriptions.

99 et passim, _for_ Paecilasma, _read_ Poecilasma.

156. In a foot-note, I have alluded to a new genus of sessile
Cirripedes, under the name of Siphonicella, I now find that
this species has been called, by Professor Steenstrup,
_Xenobalanus globicipitis_.

MONOGRAPH

ON

THE CIRRIPEDIA.

INTRODUCTION.

I should have been enabled to have made this Volume more complete, had I
deferred its publication until I had finished my examination of all the
other known Cirripedes; but my work would thus have been rendered
inconveniently large. Until this examination is completed, it will be
more prudent not to discuss, in detail, the position of the Lepadidae
amongst the Cirripedia, or of these latter in the great class of
Crustacea, to which they now, by almost universal consent, have been
assigned. I may, however, remark that I believe the Cirripedia do not
approach, by a single character, any animal beyond the confines of the
Crustacea: where such an approach has been imagined, it has been founded
on erroneous observations; for instance, the closed tube within the
stomach, described by M. Martin St. Ange (to whose excellent paper I am
greatly indebted), as indicating an affinity to the Annelides, is, I am
convinced, nothing but a strong epithelial lining, which I have often
seen ejected with the excrement. Again, a most distinguished author has
stated that the Cirripedia differ from the Crustacea:--1st. In having "a
calcareous shell and true mantle;" but there is no essential difference,
as shown by Burmeister, in the shells in these two classes; and
Cirripedes certainly have no more claim to a mantle than have the
bivalve entomostraca. 2d. "In the sexes joined in one individual;" but
this, as we shall see, is not constant, nor of very much weight, even if
constant. 3d. "In the body not being ringed;" but if the outer
integument of the thorax of any Cirripede be well cleaned, it will be
seen, (as was long ago shown by Martin St. Ange), to be most distinctly
articulated. 4th. "In having salivary glands;" but these glands are, in
truth, the ovaria. 5th. "In the liver being formed on the molluscous
type;" I do not think this is the case,