Pleuiiobraxchus. 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 Limaw ; tentacula or feel- 

 ers two, flat, but usually roUed 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 ai'e 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 tliat 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 Planariae. 



Gen. XLV. PLEUROBRANCHUS.— 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 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 papilljp ; 

 foot rounded, with an irregularly indented margin. 



x2 



