526 STUDIES ON AUSTRALIAN MOLLUSCA, IX., 



RiSSOA EMBLEMATICA, 11. Sp. 



(Plate xxxii., fig.24.) 



A " Rissoa " of the group of R. cheilostoma, small, short, stout, 

 solid and glossy. Whorls four, parted by impressed sutures, the 

 first three forming less than half the shell, the last becoming 

 ultimately detached. Colour : amber, darkening to brown on the 

 base, peristome white. Sculpture : the minute umbilicus is 

 margined by a heavy spiral ridge which runs up into the anterior 

 corner of the peristome. To this succeeds a groove and a second 

 spiral ridge, upon which are planted the bases of a dozen thick, 

 oblique radiating ribs. Ascending to the shoulder, these ribs 

 there project as heavy buttresses, giving to the whole shell a 

 peculiar angular expression. From the shoulder these ribs 

 diminish rapidly to the suture, which they undulate. The 

 shoulder buttresses are linked each to the next by a spiral ridge. 

 On the last whorl behind the aperture, the radial ribs vanish, 

 but the shoulder links continue to the peristome as a prominent 

 undulating cord. A secondary sculpture of minute spiral undu- 

 lating scratches covers the entire surface without reference to 

 the features of the major sculpture. The basal cord, radiating 

 buttress ribs and shoulder links are repeated on the third whorl. 

 The second whorl is broadly tabulate, but unsculptured. The 

 apex is tilted, so appearing papillate. Aperture in the plane of the 

 axis, oblong, surrounded by a heavy, widely projecting, complete 

 peristome, doubled by a groove on its face. Length 4, breadth 

 2 mm. 



ZTrt^.— Manly Beach, Chinaman's Beach {Miss L. Parkes), 

 Middle Head and Wreck Bay, N.S.W. (C. Hedley). 



Type. — To be presented to the Australian Museum. 



From its nearest allies the comparative simplicity of sculpture, 

 the predominance of radii over spirals, distinguish it. 



RissoA PULVILLUS, n.sp. 



(Plate xxxii., fig. 25.) 



Shell small, oblong-ovate, imperforate, thin and glossy. Whorls 

 four and one-half, inflated. Colour : upper part uniform ochreous- 



