696 STUDIES ON AUSTRALIAN MOLLUSCA, xii., 



Posterior area large, margined by a ridge radiating from the 

 umbones to the extremity. Lunule narrow, defined by a groove. 

 Posterior dorsal margin excavate, anterior dorsal margin convex, 

 ventral margin gently curved, posteriorly acuminate, anteriorly 

 rounded. Sculptured with close concentric cords, except along 

 the rostrum where there is a smooth ray. Teeth small, about 

 twenty on the anterior side, and sixteen on the posterior. Speci- 

 men figured is, in length, 8; height, 4; depth of single valve, 

 1-7 mm. Another specimen, length, 12; height, 6; depth of 

 single valve, 1-7 mm. 



Hah. —Van Dieman's Inlet, 5 fathoms (type), and off the Horsey 

 River, o fathoms, mud. Both places in the Gulf of Carpentaria, 

 self, 1903. 



This species has a general resemblance to L. novceguineensis 

 Smith, but is narrower, more sharply sculptured, and wants the 

 smooth submedian ray. L. mauritiana Sowerby, is more inflated, 

 and taller in proportion to length. 



Leda nakthecia, sp.nov. 

 (Plate Ixxviii., figs.l2, 13, U.) 



Shell rather solid, slightly inequilateral, ovate-acuminate, 

 inflated. Dorsal margin straight, ventral margin curved, pos- 

 teriorly pointed, anteriorly rounded. Colour lavender-grey dor- 

 sally, shading to cream-buff ventrally. Sculpture none, surface 

 very smooth and glossy wdth an iridescent sheen. Rostrum, 

 lunule, and posterior area not well defined. Beaks full and pro- 

 minent. Teeth about eighteen on each side. Length, 10-3; 

 height, 6; depth of single valve, 2 mm. 



Hab. — In mud, 5 fathoms, off Horsey River, Gulf of Carpen- 

 taria, several specimens (self, 1903). 



POROLEDA SPATHULA, Sp.nOV. 



(Plate Ixxviii., figs. 17, 18.) 



Leda ensicula Hedley, Mem. Aust. Mus., iv., 1902, p.293, f.41 

 (not of Angas). 



It was kindly explained to me by Mr. Hugh Fulton, that I 

 had fallen into error regarding Leda ensicula Angas. The shell 

 which I had so identified is, as he explained, "flatter, more nar- 



