Pleurobranchus. MOLLUSCA. BRANCHIFERA. 291 
on the right side, under a lid, capable of expanding into a complicated plu- 
mose ridge ; within the longitudinal lips are two corneous plates or jaws. 
This animal pours out a purple fluid from under the branchial lid when taken. 
166. A. punctata. — Body brown, with numerous white spots. 
Cuv. Moll. t. i. f. 3-5. Flem. Edin. En. xiv. p. 623.— Coast of Devon 
and Orkney. 
This species resembles the last in structure, and differs in nothing but co- 
lour. Cuvier indeed states, as a distinguishing character, the naked central 
spot on the lid; but this is accidental. Montagu informed me, by letter 17th 
February 1811, that this animal was common along with the other kind (of 
which he considered it, probably justly,' as a variety), and so large “ as to fill 
a moderate sized tea-cup.” It has only once occurred to myself in the Bay 
of Kirkwall, though the A. depilans is common on the Scottish coast. 
167. A. viridis, — Body of a green colour. 
Mont. Linn. Trans, vii. t. vii. f. 1. — Coast of Devon. 
“ With the fore-part of the body like a common Limax ; tentacula or feel- 
ers two, flat, but usually rolled up, and appear like cylindric tubes ; at a little 
distance behind the tentacula, on each side, is a whitish mark, in which is 
placed a small black eye ; the body is depressed, and spreads on each side into 
a membranaceous fin, but which gradually decreases from thence to the tail, 
or posterior end ; this membranous part is considerably amorphous, but is 
usually turned upwards on the back, and sometimes meeting, though most 
times the margins are reflected ; this, as well as the back, is of a beautiful 
grass-green colour, marked on the superior part of the fins or membrane with 
a few small azure spots, disposed in rows ; the under part with more numer- 
ous, but irregular, spots of the same ; the fore-part of the head is bifid ; the 
lips marked by a black margin ; the sustentaculum is scarcely definable, as it 
most commonly holds by a small space close to the anterior end, and turns 
the posterior end more or less to one side ; it sometimes, however, extends 
itself for the purpose of locomotion, in which it scarce equals a snail.” — “ Al- 
though this animal does not strictly correspond with the characters prefixed 
by Linnaeus to the genus Laplysia., yet it approximates so nearly to the de- 
pilans^ in its external form^that we cannot hesitate to place it with that ani- 
mal, though we could not discern any membranaceous plate or shield under 
the skin on the back.” Mont . — The characters here assigned to this species 
are such as to excite the belief that it is not an Aplysia ; but they are not 
sufficiently minute to enable us to establish another genus for its reception. 
It is probably related to the Planarije. 
Gen. XL V. PLEUROBRANCHUS.—Tentaculatwo ; cloak 
and foot expanded, the former strengthened by a thin ex- 
panded subspiral shell. 
168. P. plwmula. — Cloak broad, reticulated ; foot pointed. 
Bulla plumula, Mont. Test. Brit. 214. vig. 2. f. 5 ; the shell t. xv. f. 9. 
— Coast of Devon. 
Length about an inch ; pale yellow ; tentacula broad, with eyes at the base 
above ; feet large, with waved edges ; branchia, a plumose appendage on the 
right side. -—The shell is oval, depressed, pellucid, thin, concentrically 
wrinkled, with a minute single whorl near one end. 
169. P. memhranaceus. — Cloak covered with conical papilla? ; 
foot rounded, with an irregularly indented margin. 
T 2 
