PLEUROBRANCHUS. 



Cuvier. 



TESTA interna, dorsalis, haliotoidea, tenuis, 

 supernfe convexiiiseula, vertice laterali, subter- 

 minali, inflexo. 



FiRsrnoticed and described under the denomination of Bulla 

 Pliimula,^ by Montagu, who has described the animal as 

 well as the shells, although our continental neighbours 

 have not chosen to give him the credit of having first 

 made known this very remarkable animal. The name 

 applied to the animal by Cuvier, refers to the position of 

 the Branchice, which form a sort of feather-like appendage 

 attached to its right side. It is observable that this name 

 has no reference to the shell, a circumstance which would 

 be much to be regretted, but that the shell is so slender 

 and thin that it is scarcely likely to be met with separate 

 from the animal. The general form of the shell is very 

 much like that of an Haliotis, it is very thin, and is placed 

 on the back of the animal, being entirely internal and 

 hidden by the integuments : it is rather convex on the 

 outer or upper side, with a lateral, nearly terminal, in- 

 flected vertex. 



Few species of this Genus are known as yet, though it 

 is probable that there are many; two, at least, are natives 

 of our own coasts, and several others are known as in- 

 habitants of the coasts of the Red Sea; they have lately 

 been described by Riippell. There are no fossils which 

 can be referred with certainty to this Genus. 



* See Mont. Test. Brit, 2nd Vignette f. . 1803. For another species 

 which Montagu has called Lamellaria membranacea, see Linn. Trans. 



