177 



South Australia: Oyster beds at Nor'- West Bend; very 

 abundant in the calciferous sand-rock of the Eiver Murray 

 Cliffs, near Morgan ; in a well-sinking at " Nine-Mile Camp," 

 near Nor'-West Bend. Victoria : Upper and lower beds at 

 Muddy Creek; Corio Bay; Schnapper Point. 



From the living C. sulcata, Lamarck, to which it has been 

 referred, our fossil species differs in being less inequilateral, 

 more pointed posteriorly, less gibbous, &c. A nearer ally 

 among existing species is C.fortisulcata, E. Smith, from which 

 it differs particularly in its truncated posterior margin. 



Corbula pixidata, spec. nov. Plate xvii., figs. 12a— 126. 



Ovately rhomboidal, rather solid, inequilateral, subinequi- 

 valve, moderately convex ; the posterior side is a little pro- 

 duced, obliquely truncated, and sharply carinated from the 

 umbo to the post-ventral angle. The umbones are in the 

 anterior third, rather inflated, depressed, and incurved. The 

 left valve is a little smaller than, and included within, the 

 suberect ventral and posterior margins of the right valve ; both 

 are equally convex. 



Both valves have the same ornamentation, which consists of 

 angular concentric ridges and radial stria? ; the ridges are 

 usually numerous, fine, and close together, but are sometimes 

 thicker and fewer. 



Dimensions of a large specimen. — Antero-posterior diameter, 

 105 ; umbo-ventral diameter, Go ; sectional diameter through 

 both valves, 5 millimetres. 



Localities. — Common in the Turritella clays at Blanche 

 Point, Alclinga, and corresponding beds in the Adelaide bore. 



G. pixidata is much like the young of the last species, but it 

 is less inequivalve, more convex, with larger umbones, and is 

 proportionately shorter. 



Neaera subrostrata, spec. nov. Plate xv., figs. 2a— 26. 



Ovate, inequilateral, produced into a long beak behind, 

 moderately convex, thin ; front dorsal margin slightly convex 

 and considerably sloping, the post-dorsal part somewhat longer, 

 less oblique, and moderately concave ; the ventral margin is 

 irregularly arched, sinuated in front of the rostral prolonga- 

 tion. A distinct keel starts from behind the umbo, is directed 

 towards but does not extend so far as the lower corner of the 

 rostrum. 



The ornament consists of coarse concentric lines of growth, 

 becoming lamellose at the umbo and rostral insinuation. 



Eight valve with an elongate lateral tooth on the posterior 

 side ; left valve edentulous ; cartilage-plate well developed, 

 obliquely inclined backward. 



