61 



and somewhat sloping, the antero-dorsal one is slightly incurved :. 

 the ventral margin is nearly straight, but slightly insinuate pos- 

 teriorly. The umbo is small and acute. 



The shell is thin, concentrically coarsely striated or folded ; the 

 colour is yellowish, whitish, or pink, usually varied with brown 

 rays, those at each extremity are broader and more frequently 

 present. 



Dimensions. — Antero-posterior diameter, 18 ; umbo-Axntral 

 diameter, 11 -5; sectional diameter of united valves, six milli- 

 metres. 



Locality. — Common on the beach at Royston Head (JfaUheivs). 



This species must not be confounded with J/. Jacksoniensis, 

 from which is distinguished by its coarse ornament, less arched 

 ventral margin, its blunt posterior margin, the less defined post- 

 dorsal area and the equilaterality. From J/. 2ncsina, A. Adams, 

 it differs by not being acuminate at both ends. 



Raeta meridionatis, spec. nov. Plate xi., fig. 3. 



Shell whitish, very thin, translucent ; ovately - suboblong,. 

 moderately convex antemedially, posteriorly gaping ; umbo sub- 

 acute, curved forward, situated in the anterior three-sevenths. 



Anterior margin regularly rounded, ventral margin strongly 

 arched ; dorsal line sloping on both sides, more so in front than 

 behind ; posterior side narrowed and depressed, its margin some- 

 what squarely truncated and slightly reflected. There is an ill- 

 defined depressed post-dorsal area, but no umbonal ridge. 



Sinus Avidely rounded, horizontal, reaching to the centre, visible 

 on the exterior. 



Surface marked by fine lines of growth, which become more 

 conspicuous and finely wavy wrinkled on the post-dorsal area, 



Dimensions. — Antero-posterior diameter, 35 ; umbo-ventral 

 diameter, 30; sectional diameter of left valve, eight millimetres. 



Locality. — One valve collected by Mr. Magarey on the beach of 

 Aldinga Bay. 



Venerupis iridescens, spec. nov. Plate xi., fig. 10. 



Shell rhomboidal, subdepressed ; post-dorsal line straight ; 

 anterior side very short and narrow, slightly concave in front of 

 the depressed acute umbo ; posterior side long, expanded, 

 squarely truncated at its margin, but rounded off j)ost-ventrally ; 

 there is no defined umbonal ridge ; ventral margin having a 

 slight out^^'ard curve in its posterior half, thence rapidly ascend- 

 ing to the roundly attenuated front ; umbo in about the anterior 

 third. 



Colour dii-ty white, iridescent, with a few spots of reddisli 

 brown. Ornament of concentric laminse (about 15 consj^icuous 

 ones), and three or four concentric rounded threads in the inter- 



