Fam. 1, Plates 1 and 2.
Genus 1. DORIS,* Linn.®us.
Corpus ellipticum, depressum, rariua convexurn, pallio plerumque tuberculato obtectum; pallium
ultra caput et pedem extensum. Caput inferius, tentacuHs 2 labiaHbus, nonnunquam obsoletis, vel in
velum conjunctis. Tentamla dorsalia 2, subclavata et laminata, infra foramina retractilia. Branchix
plumosee, anum circumdantes, postice in lined, media dorsi positse. Apertura genitalis ad latus
dextrum.
When Linnseus first proposed the genus Boris, in the tenth edition of the ‘ Systems
Naturse,’ he so far misunderstood its characters as to describe the vent for the mouth, which
he conceived to be surrounded by a circle of tentacles. This mistake, pardonable in that
early stage of science, he corrected in the twelfth edition of his celebrated work, and the
genus, as there described, and for the first time properly established, is pretty nearly the
same as it is now understood by zoologists of the present day. Gmelin, however, so much
enlarged the limits of the genus Doris es to make it nearly co-extensive with the whole order
of the-Nudibranchiate Mollusca, and his example was followed by most of the naturalists of
the Linnsean School. In the more accurate classification of Cuvier, Doris was again reduced
within the limits of the Liiinaean characters, though from the imperfect knowledge of these
animals still at that time prevailing, many species were at first included in it, which were
afterwards detached to form new genera, as these characters became better understood. It is
not necessary to enumerate the genera that were thus formed, as most of them will be found
described m the family of the Doridida. Even as at present restricted, the genus still
contains a large number of species, and that number is daily being increased by the discoveries
o modern travellers, as well as by the more careful investigation of native species by
European zoologists. As yet the different groups are scarcely sufficiently understood to allow
of a satisfactory division of the whole genus-; but at some not very distant period, such a
division wdlj'certainly be required, and distinctive characters are not wanting on which
several new genera might be established. Before noticing some of the attempts that have
been made towards the accomplishment of this object, it will be necessary to give a more
detaded view of the characters of the genus as it at present stands.
The body Of Doris is elliptical, and generally more or less depressed, but in some species
convex. It is covered on aU sides by a cloak, which extends beyond the head and foot; the
stiffened I B 1 Percolated or granulated, seldom quite smooth, and is more or less
iffened with calcareous spicula, imbedded in its substance. The head is indistinct, placed
* Doris, a sea-nymph, daughter of Oceanus and Thetys.