GASTEROPODA NUDIBRANCHIATA. 
351 
I From the observations of Van Hasselt it seems that we must here arrange 
I The Scarabes, Montf. 
i The shell is oval, and the aperture contracted by large teeth projecting from both the columellar side 
I as well as the outer lip : this lip is swollen, and as the 
animal re-makes it after every half-whorl, the shell is most 
protuberant on two opposite lines, and has a flattened 
aspect. The animals live on aquatic plants in the Indian 
Archipelago. 
The two genera which follow were misarranged among 
j the Volutes. 
I Auricula, Lam., — 
Differing from all preceding aquatic Pulmonea by having 
I their columella striated with large oblique channels. Their 
' shell is oval or oblong; the aperture of the shape of the Bulimus or Limnaeus ; the lip furnished with 
j a varix. Several species are of considerable bulk ; but it is not ascertained if they live in marshes, 
I like the Limnaeus, or merely upon their margins, after the manner of the Succinea. 
j [One species, according to Lesson, lives in fresh water ; the others appear to be terrestrial, living on rocks by 
j the sea-side.] We find only one in France, from the coast of the Mediterranean {Auricula myosotis, Drap.) The 
mate has two tentacula, and the eyes are at their bases. \CarycMum, Muller, answers so nearly to the description 
of Auricula, that the genera ought probably to be conjoined. The typical species (C. minimum) lives under leaves 
in shaded woods.] 
The Melampes, Montf. {Conovulm, Lam.), 
Like the Auricula, have prominent plaits on the columella, but their aperture has no varix, and its 
inner lip is finely striated : the shell has somewhat the shape of a cone, of which the spire makes the 
base. They inhabit the rivers of the Antilles. 
THE SECOND ORDER OF THE GASTEROPODES. 
THE NUDIBRANCHIATA.* 
They have neither a shell nor pulmonary cavity, but their branchiae are exposed naked 
upon some part of the back : they are all hermaphroditical and miarine : they often swim in a 
reversed position, the foot applied against the surface, and made concave like a boat ; and 
they assist their progress by using the edges of the cloak and the tentacula as oars. 
The Doris, Cuv., — 
Have the anus in the posterior part of the back, and the branchise are arranged in a circle round the 
anus ; and as each resembles a little arbuscule, they constitute alto- 
gether a sort of flower. The mouth is a small proboscis, situated 
under the anterior edge of the cloak, and is furnished with two small 
conical tentacula. There are other two tentacula, of a conoid figure, 
[and lamellated structure,] which issue from the superior and ante- 
rior part of the cloak. The organs of generation have their orifices 
near to each other, under its right margin. The stomach is membranous. A gland, intimately inter- 
laced with the liver, sheds a peculiar secretion, that escapes outwards by a hole near the anus. The 
species are numerous, and some of them of considerable size. We find them on the shores of every 
sea.f Their spawn is shed in the form of a gelatinous ribbon, on rocks and sea-weeds, &c. 
The Onchidores, Blainv., only differ from the Doris in the wider separation of their sexual organs, whose orifices 
communicate by a furrow drawn along the right side, as in the Onchidia. The Plocamoceres, Leuckard, have all 
the characters of Onchidores, and moreover the anterior edge of their cloak is adorned with numerous branched 
tentacula. The branchiae of Polycera, Cuv., are like those of Doris, but simpler, and furnished with two mem- 
Fiu. Ifi4 — Doris coriiuta. 
Fig. 163. — Auricula scarabseus. 
* My first four orders are joined together by M. de Blainville into 
what he calls a sub-class, and names Paracephalophora monoica. Of 
my Nudibranchiata he makes two orders : in the first (^Cpclobranchi- 
ata) he places the Dorides ; in the second {Polpbranchiata) the 
Tritoniae and its allies, which he divides into two families, according 
as they have two or four tentacula. 
t The Scottish species are described by Dr. Johnston in the 1st 
vol. of the Annals of Natural History ; and Montagu has described 
many British species in the Linnaan Transactions. — Ed. 
