NUCULA CONCENTRICA. 



SrECIFIC CHARACTER. 



Transversely elongate-subovate, rostrated, concentrical- 

 ly striated. 



SYNONYM, 



NucuLA CONCENTRICA. NoMs. Joum. Acad. Nat. So. 

 vol.iv, p. 141, pi. 10, fig. 6. 



DESCRIPTION. 



Shell convex : rostrum considerably narrowed towards 

 the tip : surface concentrically striated with numerous, 

 regular, equidistant, rounded lines : beaks rather behind 

 the middle : ligament margin a little concave ; series of 

 teeth angulated at the beaks. 



OBSERVATIONS. 



The regularly striated surface gives this shell a very 

 pretty appearance. In outline it has some resemblance to 

 the rostrata. 



REFERENCE TO THE PLATE. 



The lefl hand figures exhibit Ihe exterior and interior viewi. 

 PL.\TE XII. G 



