100 COLLECTIONS FKOM MELANESIA. 



and bifid, and two in the left, of which the anterior is the larger and 

 bifid. A single lateral tooth occurs in the right valve on each side 

 not far from the cardinals, with a groove between them and the 

 margin. Left valve with a slight tooth-like projection on the mar- 

 gin on each side fitting into the grooves in the other valve. The 

 pallial sinus is largo and deep. Internal cartilage minute, narrow, 

 oblique, posterior to the cardinal teeth. External ligament small. 

 The largest specimen measures 13 millim. by 9|. T. alba of Wood 

 is somewhat like this species, but is more acute posteriorly, the 

 detail of its dentition is different, and the cartilage larger. 



27. Mactra exirnia. 

 (Deshayes) ; Reeve, Conch. Icon. fig. 31 (rayed variety). 



Hab. Port Denison, Queensland (Coppinger) ; Port Curtis, More- 

 ton Pay (coll. Owning) ; X.E. coast of Australia (Brit. Mas.). 



There are altogether eight specimens of this species in the Museum, 

 three of them being ornamented with numerous reddish rays, and 

 the remaining five uniformly white beneath the greyish and yellowish 

 epidermis. 



28. Mactra producta, var. 



Spisida producta, Angus, Proc. Zool. Soc. 1867, p. 909, pi. 44. fig. 7. 



Hab. Port Jackson (Angas and Coppinger). 



The three shells dredged by Dr. Coppinger are probably a variety 

 of this species. They are all small, apparently immature, and differ 

 from the types presented to the Museum by Mr. Angas in being 

 less produced posteriorly. They are proportionally longer from the 

 umbones to the ventral margin, which exhibits a very faint incurva- 

 tion near the hinder extremity, and the posterior dorsal slope is a 

 trifle more arcuate. 



29. Mactra (Oxyperas) coppingeri. (Plate VII. figs. D-D 2.) 



Shell transversely elongate, triangular, a little inequilateral, 

 rather compressed, thinnish, narrowly gaping posteriorly, smooth 

 towards the beaks, concentrically plicately ridged elsewhere, white, 

 covered with a pale yellowish epidermis, spotted somewhat sparsely 

 throughout with brownish dots, and ornamented on the dorsal areas 

 with cross lines of a deeper brown, and with a large patch of the 

 same colour on the hinder slope of each valve. Umbones moderately 

 acute, not large, inclining towards and situated a trifle in advance 

 of the centre. Lunule sunken, not circumscribed by acute ed 

 extending more than halfway down the anterior slope. Posterior 

 area as deep as the lunule and a trifle longer, smoothish, not much 

 affected by the terminations of the concentric ridges. Two lateral 

 teeth on each side in the right valve, separated by a deep gr> 

 quite approximated to the cardinal teeth in front and the cartila 

 pit behind. The latter is large, deep, and located posterior to the 

 beak. The cardinal tooth is small, insignificant, bounds the ligament, 

 and has a cross piece above it immediately beneath the apex of the 



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