l be seen that _Mitella_ of Oken, and
_Ramphidiona_ of Schumacher, are both prior to _Pollicipes_ of
Leach; yet, as the latter name has been universally adopted
throughout Europe and North America, and has been extensively
used in geological works, it appears to me to be as useless as
hopeless to attempt any change. It may be observed that the genus
_Pollicipes_ was originally proposed by Sir John Hill ('History
of Animals,' vol. iii, p. 170), in 1752, but as this was before
the discovery of the binomial system, by the Rules it is
absolutely excluded as of any authority. In my opinion, under all
these circumstances, it would be mere pedantry to go back to
Oken's 'Lehrbuch der Naturgeschichte' for the name _Mitella_,--a
work little known, and displaying entire ignorance regarding the
Cirripedia.

_Valvae ab 18 usque ad 100 et amplius: lateribus verticilli inferioris
multis; lineis incrementi deorsum ordinatis: sub-rostrum semper adest:
pedunculus squamiferus._

Valves from 18 to above 100 in number: latera of the lower whorl
numerous, with their lines of growth directed downwards: sub-rostrum
always present: peduncle squamiferous.

Hermaphrodite; filamentary appendages either none, or numerous and
seated on the prosoma and at the bases of the first pair of cirri;
labrum bullate; trophi various; olfactory orifices generally highly
prominent; caudal appendages uni-articulate and spinose, or
multi-articulate.

Attached to fixed, or less commonly to floating objects, in the
warmer temperate, and tropical seas.

It has been remarked, under Scalpellum, how imperfectly that genus is
separated from Pollicipes; and we have seen under _Scalpellum villosum_
that the addition of a few small valves to the lower whorl, would
convert it into a Pollicipes, most closely allied to _P. sertus_ and
_spinosus_. It has also been shown, that the six recent species of
Pollicipes might be divided into three genera, of which _P. cornucopia_,
_P. elegans_, and _P. polymerus_, would form one thoroughly natural
genus, as natural as Lepas and the earlier genera; _P. mitella_ would
form a second; and _P. sertus_ and _P. spinosus_ a third; but I have
acted to the best of my judgment in at present retaining the six species
together. As far as the valves of the capitulum are concerned, it would
be very difficult to separate _P. mitella_ from _P. sertus_ and
_spinosus_.

_Description._ The number of