GASTEROPODA. 



159 



I'hurobranehus. 



somewhat tubular ; the foot is strong, thick, with an oval 

 sole. — 4 species. 



From the Mediterranean and the coast of Norway. 



Pleurobranchus. Cuvier. (Lamellaria Montf.) — 

 Shell thin, nearly flat and obliquely 

 oval ; apex near the edge ; internal, ^| 

 or covered by the animal, which 

 is oblong, or suborbicular, fleshy; 

 head with two grooved tentacula, the eyes at their ex- 

 ternal bases ; a broad tentaculiform buccal veil ; mouth 

 provided with corneous jaws, and an armed lingual ribbon ; 

 branchial plume single, free towards its extremity, placed 

 on the right side between the mantle and foot ; the latter 

 is ample, separated from the mantle by a deep groove.* — 

 Many species. 



Found in the Indian seas and the Mediterranean : the 

 animal often exhibits gay colours. 



Pleurobranch^a. Meckel. (Pleurobranchidium 

 Blain. ; Cyanogaster Rudolphii.) — No trace of a shell. 

 Animal, having the edge only of the mantle placed a little 

 forward, and extending in front into four tentacula, which 

 are but short, the hinder ones are also ear-shaped; the 

 gill projects a little, and is not deeply divided, as in PUu- 

 robranchus, and the anal opening lies not behind, but over 

 it. — 2 species. 



P. Meckelii is found in the Mediterranean ; and P. ma- 

 culata is also mentioned by Quoy and Gaimard. 



PoSTEROBRANCHiEA. D' Orb. — Shell none. Animal, 

 having the mantle broad, oval, like that of Pleurobranchea, 

 the front is separated from the head by a shallow notch ; 

 the tentacula are entirely absent ; the anal opening, and 



* Forbes's British Moll. 



