468 STUDIES ON AUSTRALIAN MOLLUSCA, X., 



sion, and on the assurance of its immaturity. From juvenile 

 examples of that species (now known as Capulus australis Lamk.) 

 the novelty appears to differ by greater symmetry and less height 

 in proportion to breadth. Amalthea coxi Sowerby,* from Port 

 Stephens, seems to me not molluscan, but the shell of a barnacle. 



RlSSOA PRAEDA, n.Sp. 



(Plate x., fig.35.) 



Shell small, solid, ovate-conic, imperforate. Whorls six, rather 

 rapidly increasing. Colour uniform pale ochreous. Sculpture : 

 the base as far as the periphery is smooth. Above the periphery 

 are eleven massive perpendicular ribs which continue from whorl 

 to whorl to the antepenultimate. The deep wide interstices 

 appear at the periphery to be gouged out of the shell-substance. 

 Both ribs and interstices are smooth. Apex bare of sculpture. 

 Aperture a little oblique, ovate, angled above, externally pro- 

 tected by a heavy outstanding varix, inner lip with a thickened 

 reflected edge. Length, 3*55; breadth, 215 mm. 



Two specimens collected in Middle Harbour by the late Mrs. 

 Starkey. 



Type to be presented to the Australian Museum. 



RlSSOA INCOMPLETA, II. sp. 



(Plate x., fig.36.) 



Shell small, ovate-globose, rather thin, glossy, translucent, 

 imperforate or very narrowly perforate. Whorls five. Colour 

 uniform flesh-pink, varix white. Sculpture : about twenty-one 

 sharp narrow perpendicular ribs, parted by broad shallow inter- 

 'stices, traverse the last two whorls from suture to periphery, 

 where they are abruptly closed by a waved spiral cord. On the 

 base the ribs faintly reappear. Upper whorls and base smooth. 

 Aperture subquadrate, anteriorly subchannelled. Columella 



* Proc. Malacol. Soc. viii. 1908, p. 17, Pl.i. figs.9-11. 



