430 



NEW SOUTH WALES MOLLUSCA, 



For some time I have had under consideration a minute bivalve,, 

 obtained by several collectors, including myself, as dead and 

 sepai'ate valves washed ashore on rocky places near or facing the 

 ocean round Sydney. The position of the ligament and the 

 entire pallial line appeared to throw it into the vicinity of 

 Sarepta. Yet the totality of the remaining characters revolt 

 against the definitions both of that genus and of its subfamily, 

 drawn up by Dall. Excluding these two points my shell would 

 rather he associated with such a group as Trinacria. Round 

 Lecla there have been arranged forms which, while preserving the 

 same hinge type, have in contour assumed as great divergence as 

 parts Sarepta from the shell in question. So I have, in disregard 

 of remaining features, followed the clue offered by the more 

 important taxonomic characters and with diffidence invite the 

 attention of systematists to my puzzle under the title of : — 



AUSTROSAREPTA, g.n. 



A genus of the subfamily Sareptinse, distinguished by an amphi- 

 detic internal ligament and a distinct though feebly separated 

 resilium. Hinge line arched, teeth few, beyond which are several 

 crenulations on the dorsal margin. Valve brightly coloured, 

 subrostrate, with sharp folds proceeding obliquely from the beak 

 to the postero- ventral margin. T^^pe A. picta. 



Since the progress of evolution in the ligament has been from 

 amphidetic to opisthodetic, this genus may be considered as a 

 more primitive form than the other members of the subfamily. 



AuSTROSAREPTA PICTA, sp.n. 



(Figs. 1, 2.) 



Shell minute, moderately thick, swollen, inequilateral, obliquely 

 subquadrate. Colour variable, rarely all violet, usually mottled 

 in different patterns by brown on a pale horn ground. Umbo 

 not turned either anteriorly or posteriorly, elevated, rounded, 

 situated at about one-third of the total length from the anterior 

 end. Ligament amphidetic; beneath it a V-shaped depression 



