69 



small, acute, hardly projecting beyond the dorsal margin, 

 situated a little in front of the centre ; posterior side the 

 larger. The sculpture consists of fine concentric striae. 



Left valve with two diverging teeth, between which is the 

 cartilage pit. 



Dimensions. — Antero-posterior diameter, 10 ; umbo-ventral 

 diameter, 8 ; sectional diameter of both valves, 4 millimetres. 



Localities. — Shell sand, Aldinga Bay and Port Lincoln. 



Scintilla (?) lunata, spec. nov. Plate iv., fig. 8. 



Shell minute, approximately semicircular in outline, sub- 

 equilateral, compressed, yellowish-white, dull, translucent ; 

 umbones small, though prominent, median, smooth. Surface 

 of the valves concentrically faintly striated, and towards the 

 margin minutely papillose, with a few larger papilke grouped 

 somewhat radially. 



Dorsal line straight, the rest of the periphery almost uni- 

 formly arched, the posterior side being a little more attenuated 

 than the anterior. Ventral gape wide, lanceolate. Ligament 

 internal, bounded on each side in each valve by an obtuse 

 tooth with a bifid crown and a long lateral. Margin of valves 

 plain ; interior nacreous, with the growth lines well shown. 



Dimensions. — Greatest length of dorsal line, 7*25 ; greatest 

 width, 3*5 millimetres. 



Locality. — Creeping on rocks at extreme low tide at Edith- 

 burg, St. Vincent Gulf (McDougall !) 



Cardita rosulenta, spec. nov. Plate v., fig. 3. 



Shell trapezoidally ovate, transverse, moderately convex, in- 

 equilateral ; umbones oblique incurved ; anterior side short, 

 obliquely and roundly truncated and flattened posteriorly ; 

 post-dorsal margin straight, slightly sloping; front-dorsal 

 margin abruptly sloping and somewhat concave in front of the 

 umbo. Lunule inconspicuous, broadly cordate, smooth. Sur- 

 face ornamented with 22 very narrow subacute ribs, the an- 

 terior ones furnished with thickish annular scales, the middle 

 and posterior ones with erect, arched, or subspinose scales ; 

 interspaces between the ribs concave, two or three times wider, 

 concentrically, distantly, and irregularly striated. 



Epidermis very thin, golden-yellow, minutely ciliate-fringed. 

 Colour of shell whitish, the ribs pink and spotted with red ; 

 interior white, flesh-coloured from the umbo to the post- 

 adductor scar. 



Dimensions. — Antero-posterior diameter, 21 ; umbo-ventral 

 diameter, 17 ; sectional diameter, 13 millimetres. Proportion 

 100 : 81 : 63. 



Localities. — Small dead shells dredged in 22 fathoms, En- 

 counter Bay, and in 32 fathoms, Backstairs Passage, and cast 



