684 STUDIES ON AUSTRALIAN MOLLUSCA, xiii., 



Umbo small, incurved. Lunule rather broad, margined by a 

 shallow groove, beyond which is a low broad fold. Sculpture : 

 irregular, weak, concentric growth-lines, across which runs a 

 series of delicate and superficial radial scratches. Edge of valve 

 smooth and thin. Height, 18; length, 19; depth of single valve, 

 6 mm. 



Hab.— Off Montagu Island, 7-10 fathoms, February, 1916, 

 (type), self. Also separate valves from the ocean-beaches round 

 Sydney. 



In general appearance, L. hilaira is like Lucina perohUqiia 

 Tate, but that is larger, more solid, more inflated, with more 

 regular, concentric sculpture. 



SOLECARDIA CRYPTOZOICA, n.Sp. 



(Plate xlvi., fig.l; PI. li., fig.40.) 



Scintilla anomala Angas, Proc. Zool. Soc, 1867 (1868), p. 928; 

 not S. anomala Deshayes, Proc. Zool. Soc, 1855(1856), p. 181; 

 nor S. anomala Deshayes, Explan. PI. xlix., figs. 13-15, Anim. s. 

 vert. Bassin de Paris, i., 1860. 



Shell thin, translucent, of a milky colour, subequilateral, 

 oblong in outline when young but becoming ovate when aged. 

 When in contact ventrally, the valves are slightly apart dorsally. 

 Ventral margins slightly curved, anterior end rounded, posterior 

 produced. In the centre, the valve is tumid, but, dorsally, the 

 margins are compressed and elevated in an arched crest on either 

 side of the umbo, which projects prominently. Surface glossy, 

 under the lens a few faint concentric threads appear, and the 

 dorsal margins are slight!}^ vermiculate. Length, 11; height, 

 8 mm. 



The animal is of a milky translucency, in pale examples tipped 

 with lemon, in darker specimens the mantle-margin and the 

 longer tentacles are orange, sometimes the most prominent 

 tentacles are tipped with scarlet. The foot is long and narrow, 

 and is thrust far out, thus enabling the animal to progress rapidly. 

 A thin transparent membrane, an outgrowth of the mantle, is 

 spread over most, if not all, of the shell. On it are numerous 

 papilla? which, round the margin, develop into tentacles. At each 



