1881.] 'lightning' AND 'porcupine' EXPEDITIONS. 943 



supports the adductor muscle on tliat side : scars otherwise incon- 

 spicuous. L. 0*4, B. 0'6.5. 



' Porcupine ' Exp. 1869 : St. 39. 1870 : Atl. 16, 17a. 



Distribution. Off Gomera, Azores ('Challenger' Exp.); 620 fms. 



C. Keeled. Tropidophora. 

 'i^ 17. Ne^ra abbreviata, Forhes. 



N. abbreviata, Forb. in Proc. Zool. Soc. 1843, p. 75 : B. C. iii. 

 p. 48; V. p. 191, pi. xlix. f. 2. 



'Porcupine' Exp. 1869: St. 10, 13, 18. 1870: Atl. 9, 36; 

 Med. 5.5, Adventure Bank, off Rinaldo's Chair. 



Distribution. Finmark to W. Scotland, W. France and Bay of Bis- 

 cay, N. Spain, Mediterranean from Naples to the iEgean ; 4-552 fms. 



Fossil. Pliocene : Belgium, S. France, Sicily. 



N. vitrea of Loven, and Corbula reflexa of O. G. Costa according 

 to Aradas and Benoit. The shell frequently wants the concentric 

 plaits or folds. 



V 18. Ne^ra ANGULARis, Jeffreys. (Plate LXXI. fig. 9.) 



• N. avgidaris, Jeffr. in Ann. & Mag. N. H. Dec. 1876, p. 498. 



'Porcupine' Exp. 18/0: Atl. St. 16, 17, 17a. A living speci- 

 men and ft few valves. 



Distribution. G. Mexico (Pourtales), N. Atlantic ('Valorous' 

 Exp.); 290-1785 fms. 



A lovely shell. 



D. Ribbed lengthwise. Spathophora. 

 > 19. Ne^ra curta', Jeffreys. (Plate LXXI. fig. 10.) 



N. curta, Jeffr. in Ann. & Mag. N. H. Dec. 1876, p. 495. 



Shell roundish-oval, with an olilique outline, globose, thin, 

 opaque, and lustreless, but semitransparcnt and glossy when young : 

 sculpture, numerous longitudinal sharp ribs on the posterior side, 

 and striae in the same direction on the other side, as well as usually 

 on the rostrum ; the sculpture of the rostrum, however, is irregular, 

 sometimes consisting of a single transverse riblet, and in other 

 specimens of more than a dozen striae, and occasionally the rostrum 

 is quite smooth ; there are also close-set and wavy concentric lines 

 of growth, which are crossed by the longitudinal scul])tnre : colour 

 white : margins rounded on the anterior side, with an oblique trun- 

 cature above, gently curved in front ; rostrum short, abruptly pinched 

 up and rounded at the point ; dorsal margin on a level with the 

 umbo on the anterior side and incurved on the other side: beaks 

 minute, inflected, and sunk ; umboncs prominent : cartilage-pit 

 small, triangular, placed immediately below the beaks : hinge-line 

 flexuous : hinge-plate thin and reflected on the anterior side, thick- 

 ened on the posterior side : teeth, a short strong triangular lateral 



1 Short. 



