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 ones 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 Planariie. 



Gen. XLV. PLLUROBRANCHUS — Tentacula two; cloak 

 and foot expanded, the former strengthened by a thin ex- 

 panded subspiral shell. 



168. P. plumula. — Cloak broad, reticulated ; foot pointed. 



Bulla plumula, Mont. Test. Brit. 214. vig. 2. f. 5 ; the shell I. xv. f. !). 

 — 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. membranaceus. — Cloak covered with conical papilla? ; 

 foot rounded, with an irregularly indented margin. 



t 2 



