908 PELECYPODA. [Eulamellibntnchia. 



terior end somewhat shorter, convex, the dorsal margin descending, 

 faintly concave ; posterior end regularly convex, the dorsal margin 

 sloping, basal margin rounded. Lunule lanceolate, excavated. 

 Sculpture consisting of 14 to 16 regular, equidistant, radiate ribs, 

 rendered nodulous or subsquamose by regular concentric lines, the 

 interspaces equal to the ribs. Epidermis horny, often covered by a 

 dark-brown coating. Colour pale or dark brown, rarely with a few 

 concentric reddish bands. Interior white, porcellanous. Margins 

 crenate. Hinge moderately broad ; right valve with a strong median 

 triangular cardinal, the anterior and posterior cardinals feeble ; left 

 valve with 2 divergent, strong, triangularly raised cardinals, the laterals 

 feeble. Ligament short, external. Adductor-scars distinct, ovate, sub- 

 equal. Pallial line simple. 



Diameter Ant.-post., 12 mm. ; dorso-ventral, 13 mm. : thickness, 

 7-5 mm. (large specimen). 



Type in the British Museum. 



Hab. Off Great Barrier Island, in 110 fathoms: near Cuvier 

 Island, in 38 fathoms (Captain Bollons) ; near Channel Island, Hauraki 

 Gulf, in 25 fathoms ; Auckland Harbour. 



Fossil in the Pliocene. 



Subgen. 3. MIODONTISCUS, Dall, 1903. 



Miodontiscus, Dall, Trans. Wagn. Free Inst., iii, pt. 6, 1409. Miodoti, 

 Carpenter, 1864 ; not of Sandberger, 1870, nor of Dumeril, 1859. Type : 

 M. prolongatus, Cpr. 



Shell small, high, hinge with the posterior right cardinal absent 

 and a posterior right and anterior left lateral feebly developed. 

 Pliocene to Recent. 



6. Venericardia corbis, Philippi, 1836. Plate 53, fig. 3. 



Cardita corbis, Phil., Enum. Moll. Siciliae, i, 1836, 55. Venericardia corbis, 

 Phil. : Suter, T.N.Z.I., xxxviii, 317. Cardita unidentafa, Basterot. 



Shell small, ovato-trigonal, solid, radially ribbed, subequilateral, 

 yellowish-brown, with a few brown spots on the lunule. Beaks slightly 

 raised, convex, incurved, sharply pointed. Anterior end slightly 

 shorter, convex, the dorsal margin somewhat concave ; posterior 

 end and basal margin regularly rounded. Lunule large, lanceolate, 

 not deep. Sculpture consisting of about 11 equal, rounded, radiate 

 ribs, cut up, sometimes indistinctly, into nodules by concentric cords ; 

 interstices narrower than the ribs. Colour yellowish-brown, with 

 a few chestnut spots on the lunule and sometimes on the median 

 part of the valves. Interior white, the margins of the hinge-plate 

 and the basal margin brown. Margins crenate. Hinge area mode- 

 rately broad, solid ; right valve with a stout triangular cardinal and 

 a small anterior cardinal, posterior lateral feeble ; left valve with '2 

 strong divergent cardinals and a distinct anterior lateral. Ligament 



