CONTENTS.
rDoto pinnatifida.
PI. 45, Supplementary. *j Eolis pustulata.
'-Parasites.
46, Sup. Tongues of the Dorididae.
47, Sup. Tongues of the Eolididse.
48, Sup. Spicula of the Dorididae.
Appendix.
List of Works referred *to.
List of Plates.
Index.
Contents of parts.
A MONOGRAPH
OF THE
BRITISH NUDIBRANCHIATE MOLLUSCA.
The Mollusks whose history and characters it is the purpose of the present work to
illustrate, form an attractive group of the class Gasteropoda, until lately little noticed, and
supposed to be of small extent, hut which modern researches have brought into more
prominent importance.
As here treated of, the order N udibranchiata is restricted to those animals bearing
the character assigned to it by Cuvier, namely, the possession of distinct external and
uncovered gills. This group forms the family IHtoniens of Lamarck. Blainville has made of
it two orders,—Polybranchiata and Cyclohranchiata; and in the more recent arrangement of
Milne Edwards, it constitutes a family of his Opistobranchiata.
The Nudibranchiate Mollusca are all marine, and, with the exception of a few species,
are of small size. To some they are known by the familiar name of sea-slugs; a name,
however, not exclusively applied to them, as -it is given to several other naked mollusks,
which, like them, have a resemblance to the land slugs in the general form of their body.
The term, as applied to these animals, is far from complimentary. The land slugs are
generally sombre in colour, and plain and uninviting in form, while these little inhabitants of
the deep are often adorned with the most brilliant colours, and of forms the most varied and
graceful.
Their body is usually elongated, soft, and attached through its whole length to the foot
or disc upon which they crawl. I t is not unfrequently covered with a cloak, and in the
family DorididcB the skin is strengthened with calcareous spicula.
The head is anterior, and frequently indistinct, bearing one or two pairs of tentacles, the
upper pair of which are placed on the cloak when it is present, and behind them the eyes are