Orassatdlites.] PELECYPODA. 899 



Hob. New Zealand (Hart) ; Cook Strait. 



Remark. This is one of our rare shells, not found in many collec- 

 tions. 



2. Crassatellites obesus, A. Adams, 1854. Plate 52, figs. 9, a. 



Crassulella obesa, A. Adams, P.Z.S., 1852 (1854), 90, pi. Hi, f. 2, 2a ; M.N.Z.M., 

 158 ; Button, P.L.S. N.S.W., 526. 



Shell equivalve, inequilateral, thick, gibbous, covered with brownish- 

 red silky epidermis, transversely strongly plicated, folds prominent, 

 vanishing towards the ventral margin ; lunule impressed, lanceolate ; 

 posterior side subproduced. angled, margin truncated ; anterior side 

 gibbous, margin rounded. (A. Adams.) 



Type in the British Museum. 



Hob. New Zealand, deep water (Strange). 



Fossil in the Miocene. 



Genus 2. CYAMIOMACTRA. Bernard, 1897. 



Cyamiomactra, Bernard, Bull. Mus. Hist. Nat., Paris, 1897, 311, f. 2 ; Dall, 

 Trans. Wagn, Free Inst., iii, 1900, 1116 ; Hedley, P.L.S. N.S.W., 1905 

 (1906), 540. Type: C. problematica, Bernard. 



Shell small, equivalve, inequilateral, resembling Mactra in form. 

 Ligament internal, very oblique, nearly marginal. Muscular scars 

 very little marked ; pallial line not distinct, very likely uninterrupted. 

 Left valve having in front of the resilifer a A -shaped cardinal tooth, 

 which does not reach the dorsal margin, and 2 divergent narrow teeth, 

 one behind and one in front of the petaloid tooth. Right valve having 

 in front of the resilifer 2 divergent teeth, united at the summit, the 

 anterior of which is slightly bifid. In both valves anterior and pos- 

 terior lateral teeth are present, distinct in young shells, but indistinct 

 when adult. 



Distribution. Australasia. 



1. Cyamiomactra problematica, Bernard, 1897. Plate 52, figs. 10 

 a, b. 



Cyamiomactra problematica, Bernard, Bull. Mus. Hist. Nat., Paris, 1897. 

 311, f. 2 ; Hedley, P.L.S. N.S.W., 1905 (1906), 540, pi. 31, f. 7, 8. 



Shell small, inequilateral to subequilateral, of very variable outline, 

 thin and fragile, smooth, deep orange and white. Beaks contiguous, 

 with the prodissoconch large, convex, and shining, slightly elevated. 

 Anterior end attenuated, the dorsal margin sloping and straight, 

 narrowly arched towards the slightly convex basal margin ; pos- 

 terior end higher, subtruncated or broadly rounded, the dorsal margin 

 horizontal, very slightly descending. There is no sculpture, except 

 very fine concentric growth-lines. Epidermis smooth, lightly shining. 

 Colour bright orange from the beaks down over the posterior part 

 of the valves, anteriorly white. Interior of the same colour as the 

 outside, polished. Margins smooth, sharp. Hinge straight, with all 



29* 



