PANDORA. 61 



Oenus IVE.ERA, Ghay. 1834. 



Shell pear-shaped, inequivalve, thin, usually radiatcly rihbed, 

 beaked and gaping posteally, with au internal rib ; hinge with an 

 oblique ledge, a minute tooth contiguous, and an obsolete lateral 

 tooth ; animal with closed mantle, small crescentic foot ; siphons 

 short, contracted, upper one smallest and with an extensile valve, 

 both with a few long filaments at their sides. 



Nesera pellucida. 



Necnra pellucida, Stimpson, Inv. Gr. Manan, 21, fig. 1.3 (1853). 



Shell small, thin, pale white, sub-ovate, swollen anteally and 

 contracted posteally into a short but distinct rostrum. Beaks small, 

 tumid, and placed a little before the middle. Surface 

 nearly smooth about the beaks, with irregular, distant ^'s 378. 

 striae of growth near the margin, which become sharp 

 and well marked on the rostrum. Within smooth and 

 glossy, with minute radiating lines across the disk ; jv. peiiudda. 

 teeth very minute. Epidermis white, sometimes pale 

 greenish on the beaks and brownish on the rostrum. Length, 

 nineteen hundredths of an inch; height, twelve hundredths of an 

 inch ; width, eleven hundredths of an inch. A specimen from Casco 

 Bay measures length, five tenths of an inch ; breadth, eighteen 

 hundredths of an inch ; height, three tenths of an inch. 



The above description is copied from Dr. Stimpson, who discov- 

 ered this species, the first found on our coast. It resembles N. 

 cuspidata^ Forbes and Hanley. It was taken in forty fathoms, on 

 a muddy bottom, off Long Island. Also in a haddock taken near 

 Portland (Fowler). 



Family PANDORID^E. 



Shells irregular, inequivalve, compressed, pearly ; mantle closed; 

 branchiae of each side coalescing ; siphons separate at tips only. 



Oeniis PANDORA, Brug. 1792. 



Shell inequivalve, inequipartite, pearly within ; right valve fiat, 

 left valve convex ; hinge with two diverging teeth in the flat valve 

 and corresponding grooves in the opposite one. 



