PANDORA. 61 



Genus ]VE.*]RA, Gray. 1834. 



Shell pear-shaped, iiiequivalve, thin, usually radiately iil)l)cd, 

 ])eaked and gaping posteally, with an internal ril) ; hinge with an 

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

 tooth ; animal with eloscd mantle, small crescentic foot ; sij^hons 

 short, contracted, ui^jier one smallest and with an extensile valve, 

 both with a few long filaments at their sides. 



Nesera pellucida. 



Nem-a peJliicida, Stimpson, Inv. Gr. Manaii, 21, fig. 13 (1853). 



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

 contracted posteally into a short l)ut distinct rostrum. Beaks small, 

 tumid, and placed a little before the middle. Surface 

 nearly smooth about the beaks, with irregular, distant Fig^s-s. 

 stritB of growth near the margin, which l)ecome sharp J^v 

 and well marked on the rostrum. Within smooth and 

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

 teeth very minute. Epidermis white, sometimes pale 

 o;reenish 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 resemldes iV. 

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

 a muddy l)ottom, off Long Island. Also in a haddock taken near 

 Portland QFowIer^. 



Fa^iilt PANDORID^. 



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

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



Ocnus 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. 



