» STUDIES ON AUSTRALIAN MOLLUSCA, 



height 5 mm. The species has ah-eady been recorded from this 

 coast by Henn.* The generic title used is adopted from Ball's 

 investigations.! 



CONGERIA LUNATA, n.Sp. 



(Plate i., figs. 1-4.) 



Valves narrow, crescentic, subspiral, thin. Posterior side 

 rounded, divided by an acute keel from the anterior which is 

 concave, and infolded to one-third of the length of the shell, with 

 a slight median byssal gape. Colour white, rayed with purple, 

 under a thin gloss}' brown epidermis. Sculpture : close fine 

 waved growth-lines. Interior slightly nacreous. Septum reduced 

 to a narrow groove, ending above in a small pit. Anterior 

 cardinal margin with two or three oblique folds. Ligament 

 internal, running within the dorsal margin and curving up in a 

 groove under the umbo. Umbo acute, twisted, showing the 

 prodissoconch on the summit. Height 25, length IG, breadth of 

 conjoined valves 13 mm. 



Hah. — Keppel Bay, Queensland; one specimen collected by Mr. 

 G. L. Pilcher in 1887. 



Type to be presented to the Australian Museum. 



This species adds a genus to the Australian fauna. 



Mactra parkesiana, nsp. 



(Plate i., figs. 5-9.) 



Valves nearly equilateral, not much longer than high, rather 

 compressed, thin, rounded anteriorl}^ and ventrally, slightly pro- 

 duced and angled postei'iorly. Colour white; surface smooth and 

 glossy, under the lens appear delicate growth stride, faint radial 

 scratches and anteriorly oblique vermiculate wrinkles. Two sharp 

 narrow ridges border the posterior dorsal slope. Anterior dorsal 

 area sunken, but not sharply defined. The anterior lateral region 

 of the hinge of the right valve presents two pockets, one abo\e 



* Henn,P.L.S.N.S.W. (2), ix. . p. ISO. 

 t Dall, Trans. Wagner Inst., iii., pt.v., 1900, p. 1157. 



