PANDORA. 



GENERIC CIIAIlACTEll. 



Shell transversely oblong, inequilateral, inequivalve, un- 

 attached, regular, somewhat rostrated ; left valve flattened, 

 with from one to three teeth extended upon the inner sur- 

 face of the shell, with a fosset for the ligament ; hinge 

 margin inflected ; right valve convex, teeth one less than 

 in the left valve, with the corresponding fosset ; ligament 

 internal, attached to an elongated fosset or cicatrice, which 

 inclines tow ards the anterior margin ; muscular impres- 

 sions two, distant, lateral. 



" Animal very much compressed, elongated, in the form 

 of a sheath, by the union of the edges of the mantle and 

 its continuation with the tubes, w hich are united and very 

 short ; foot small, thicker before, exserted by a large slit 

 in the mantle ; branchiae pointed backw ards and contin- 

 ued into the tube." — (Blainville.) 



OBSERVATIONS. 



The hinge teeth extend on the inner surface of the shell 

 in some degree like those of Placlna. to which gemis, 

 this seems to be allied, both by the position of the teeth* 

 and the perlaceous consistence, of the shell ; but it is emi- 

 nently distinguished by having two muscular impressions. 

 Lamarck, who first characterized the genus, placed it next 

 to CoRBULA, chiefly, perhaps, in consequence of the ine- 

 quality of its valves. 



Two species only are described b}- Lamarck, the ina- 

 quivalvis^ Linn., and the obtusa. a newly described species. 

 Sowerby has added another, under the name of Jkxuosa. 



PLATE II. 



