940 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [Nov. 29, 



right valve, that on the posterior side extending through the middle 

 of the rostrum : inside polished : scars strongly marked on the pos- 

 terior side. L. 0'275, B. 0'35. 



'Porcupine 'Exp. 1870: Atl. St. 16, 17, 17ff, 22, 31-34. Several 

 valves and a small living specimen. 



Distrihution. Off Josephine Bank and the Azores (* Josephine ' 

 Exp.), G. Mexico; 138-790 fms. 



^ "^ 10. Ne^ra depressa^ Jeffreys. (Plate LXXI. fig. 3.) 



Shell, oval, wedge-shaped on the posterior side, depressed or 

 somewhat flattened, thin, semitransparent, rather glossy : sculpture, 

 fine and close-set minute concentric stripe in front and on tlie rostrum, 

 besides occasional lines of growth ; colour whitish : epidermis filmy, 

 apparent only on the front edge and rostrum : margins rounded on 

 the anterior side and more gently curved in front ; rostrum wedge- 

 shaped, not defined by any indentation, somewhat truncated at the 

 extremity ; dorsal margin raised and parallel with the beak on the 

 anterior side, sloping and slightly incurved on the other side : heaks 

 blunt, scarcely incurved ; umbones small and not very prominent : 

 cartilage-pit small, obliquely projecting inwards, and resembling a 

 tooth : hinge-line curved on the anterior and sloping on the other 

 side : hinge-plate thickened near the beak on each side : teeth, a 

 single laminar lateral on the posterior side of the right valve, nearly 

 parallel with the hinge-plate : inside glossy ; scar of the posterior 

 adductor muscle acutangular, defined beneath by a ridge. L. 0'2, 

 B. 0-3. 



'Porcupine' Exp. 1870: Atl. St. 16, 17, 17«. Numerous 

 valves. 



Differs from N. exigua in not being globose, having close-set con- 

 centric striae in front and on the posterior side, and in the rostrum 

 being angulated and straight. The lateral tooth also is quite differ- 

 ent; and the ridge which delines the posterior adductor muscle in 

 the present species is characteristic. 



B. Striated concentrically. Aulacophora. 

 11. Ne^ra lamellosa, M. Sars, 



N. lamellosa, M. Sars, Arct. MoUuskf. v. Norges nordljo-e Kyst 

 (1858), p. G2. 



N.juffosa, G. O. Sars, Moll. reg. arct. Norv. p. 88, t. G. f. 9, a-c. 



'Lightning' Exp. St. 2, 3. 



'Porcupine' Exp. 18G9: St. 2.3, 23a, 25, Gl. And var. l-oreiri: 

 more or less smooth or wanting the concentric ridges, and havino' a 

 broader rostrum. 1870: Atl. 3, 9, 12. 



Distribution. Finmark to Bergen coast, Bay of Biscay, Palermo, 

 New England ; 50-5.52 fms. 



Fossil. Pliocene ; Calabria and Messina. 



I am now inclined to consider the recent species distinct from 

 N.juffosa of the Coralline Crag. The fossil species is regularly tri- 



^ Depressed. 



