a lateral tooth on each side in both valves ; the anterior one in 

 the left and the posterior one in the right valve is submarginal. 



Dimensions. — Antero-posterior, 5 ; innbo-ventral, 425 ; and 

 sectional diameters, 275 millimetres. 



Locality. — Dead shells cast up in Streaky Bay, Great Aus- 

 tralian Bight. 



This species is like O. pallida, Smith, the type of the genus, 

 with which it agrees by the number of nodular ribs, but it 

 differs as from all known species by its inequilateral trian- 

 gularly ovate outline. 



The genus Carditella was established by Mr. E. A. Smith in 

 1881 (Proc. Zool. Soc, p. 42) for Cardita-like shells with well 

 developed lateral teeth on each side. It now comprises nine 

 species — three on the west coast of South America, four Aus- 

 tralian, one Cape of Good Hope, and one off Tristan da 

 Cunha. 



Limopsis rubricata, spec. nov. Plate v., fig. 6. 



Obliquely oval, inequilateral, inflated ; umbo very prominent, 

 antemedian. Hinge line straight, the anterior margin obliquely 

 descending. 



Colour whitish, with four radial flames of chestnut beneath 

 a thin light horn-coloured epidermis. The sculpture consists 

 of regular concentric strise, and towards the front margin of 

 inconspicuous radial threads. 



Margin of the valves coarsely crenulated all round. Hinge 

 line with prominent teeth — three in front and five behind. 



Probably a young shell, but not referrable to any known 

 species. 



Dimensions. — Antero-posterior diameter, 275 ; umbo-ventral 

 diameter, 3 ; sectional diameter of united valves, 175 milli- 

 metres. 



Locality. — Dredged in life from 32 fathoms in Backstairs 

 Passage. 



Pinna inermis, spec. nov. Plate iv., fig. 5. 



Yoang shells up to 100 millimetres long, triangular-elongate, 

 thin, semitransparent, slightly convex, ornamented with distant 

 depressed longitudinal ribs and imbricating lamellae of growth. 



Colour light-horn, with a yellowish-brown band along the 

 dorsal margin posterior to the ligament, and longitudinal 

 streaks of the same colour on the rest of the surface. 



The dorsal margin is straight, apical angle about 35° ; the 

 ventral margin slightly concave about the byssal orifice, thence 

 slightly ecurved, the posterior end is truncated, the post-dorsal 

 angle being 90° or less, joining the ventral margin with a 

 rapidly ascending curve. 



