1010 PELECYPODA. [Eulamellibranchia. 



3. Corbula zelandica, Quoy and Gaimard. 1835. Plate 55, fig. 4. 



Corbula zelandica, Q. & G., Voy. Astro!., iii, 1835, 511, pi. 85, f. 12-14; 

 Dieff. N.Z., 256 ; C.M.M, 61 ; Crit. List, 41 ; J. de Conch., xxvi, 44 ; 

 M.N.Z.M., 135 ; P.L.S. N.S.W., ix, 513 ; Index, 88 ; Hedley, T.N.Z.I., 

 xxxviii, 75. C. Catlowce, Reeve, P.Z.S., 1844 ; Conch. Icon., ii, 1844, 

 f. 21 ; C.M.M., (it ; Crit. List, 41. 



Shell small, oval, subtrigonal, subequivalve, inequilateral, ventri- 

 cose, thick and solid, the right valve embracing the left, both valves 

 about equally convex, strongly concentrically striated. Beaks ap- 

 proximate, not much raised, tumid, turned forward, with a posterior 

 keel. Anterior end narrowly convex, a little shorter than the posterior, 

 dorsal margin oblique ; posterior end sharply angled below, slightly 

 flaxuous, the right valve a little longer ; basal margin broadly 

 rounded. Lunule not defined. Escutcheon limited by a keel on each 

 side descending from the beak toward the posterior angle, a median 

 ridge on the right valve. Sculpture consisting of numerous fine 

 concentric striae with a number of periods of rest, marked by deep 

 grooves, much more prominent on the left valve ; fine radial striae 

 are usually present. Colour yellowish - grey. Interior reddish or 

 purplish-brown, darker at the margins. Margins smooth, usually 

 much thickened, sharp. Hinge : Right valve with an elevated, up- 

 turned tooth, and a deep resilifer behind it ; left valve with an 

 erect process behind the socket and a posterior tubercle. Ligament 

 internal. Adductor-scars unequal, the anterior pyriform. the posterior 

 roundish. Pallial line entire. 



Length, 13-5 mm. ; height, 9 mm. ; diameter, 6-7 mm. (type). 



Type in the Mus. Hist. Nat., Paris. 



Hab. Throughout New Zealand, but more common in the north. 

 The type is from Hauraki Gulf. Off Great Barrier Island, in 

 110 fathoms ; near Cuvier Island, in 38 fathoms ; near Little Barrier 

 Island, in 20 fathoms ; near Channel Island, Hauraki Gulf, in 25 

 fathoms ; off Wanganui, in 10-30 fathoms ; Wellington Harbour ; 

 Wet Jacket Arm, Dusky Sound, in 12 fathoms. Also Australia. 



Fossil in the Pliocene. 



Sect. 3. ERODONA, Daudin, 1800. 



Erodona, Daudin, Mem. Moll., Vers., &c., ? 1800 ; Ball, Trans. Wagu. Free 

 Inst., iii, pt. 4, 839. Type: Mya labiata, Maton. Potamomya, Sowerby, 

 1835. Azara, d'Orbigny, 1839.' 



Shell elongate-triangular, feebly concentrically sculptured, with a 

 conspicuous epidermis, the left umbo superior, though the left valve 

 is not the larger ; hinge of a strong, nearly vertical process supporting 

 the resilium, with a small socket on each side in the left valve ; in the 

 right valve a deep central pit for the resilium, the edges of the hinge- 

 plate bordering it turned up on each side as a narrow projection fitting 

 into the sockets opposite, but no well-defined cardinal tooth or laterals ; 

 the ligament is obsolete. (Ball.) 



