OJ 



some new and 'peculiar Mollusca. 495 



of a thin texture, and covered with a cream-coloured epidermis, 

 which is marked bj occasional lines of growth. The beak is 

 comparatively small and convoluted, turning towards the an- 

 terior side. The tooth in the right valve is short and strong; 

 and placed obliquely. Inside silvery and resplendent. 

 Station 16, 1785 fms. ; fragments. 



Necera striata'^, Jeffr. 



Shell forming a short oblong, moderately convex but not 

 globose, thin, opaque, rather glossy : sculj>ture, from 30 to 40 

 longitudinal ribs or striaj, which radiate from the beak in each 

 valve, besides a few intermediate and finer strias ; otherwise 

 they are all nearly equal in size ; in some specimens the space 

 between the beak-like end of the posterior side and the main 

 part of the shell is wrinkled transversely ; the surface is also 

 marked with numerous and close-set minute concentric lines 

 in the interstices of the ribs or stri^ : colour white : margins 

 obliquely curved in front, rounded on the anterior side, nearly 

 straight behind, and produced or extended on the posterior 

 side into a rather long rostral or beak-like projection (rounded 

 at the extremity), below which is a more or less distinct inden- 

 tation : healcs small, incurved ; umbones prominent, and pro- 

 jecting beyond the dorsal margin : cartilage contained in a 

 small oval cavity underneath the beaks : hinge-line straight, 

 or slightly upturned on the posterior side : hinge-plate narrow 

 and slight : teeth^ oi^^J ^ long triangular and erect lateral on 

 the posterior side of the right valve, being a continuation or 

 prolongation of the cartilage-pit to which it is united : inside 

 glossy : muscular scars inconspicuous. L. 0*3. B. 0"5. 



Station 12, 1450 fms.; 13, 690 fms.: altogether three single 

 valves and several fragments. ^ Challenger ' Expedition, off 

 Bermuda, 435 fms. 



This differs from JSf. costellata in being much larger, having 

 more numerous and regular ribs or stria3, which sometimes 

 alternate in size, but are not stronger on the posterior side, 

 and in the dorsal margin being nearly straight ; from an un- 

 described species dredged in the ' Porcupine ' and ' Josephine ' 

 Expeditions (which I propose to name curta) in not being 

 globose, in having a longer rostral point, and also in the 

 dorsal margin being nearly straight instead of excavated and 

 lying below the hinge-line on the posterior side. In the last- 

 mentioned species, as well as in N. costellata^ the ribs are 

 markedly stronger on that side, and are throughout unequal 

 in size, and variable according to the specimens. The present 



* Striated. 



