192 STUDIES ON AUSTRALIAN MOLLUSCA, VIII. , 



classification is correct, but adopt it as a temporary expedient 

 pending the receipt of further information. The only known 

 livinc' relation is the Tasmanian Phos tenuicostalus, Ten. Woods, 

 from which the northern shell is discriminated b}^ its small and 

 slender form and less development of longitudinal sculpture. 



Stiva, n.g. 



Allied to Rissoina. Shell with the contour of Scala rather 

 than Rissoina; large, tapering, solid. Operculum peltate, con- 

 centric. 



Type S.ferrugineoL, Hedley. 



The remarkable operculum, the chief foundation of the genus, 

 has a limb resembling that of Jeffrey sia, as figured by Alder, "^ 

 which has, however, the nucleus submarginal. 



Stiva ferruginea, n.sp. 



(Plate ix., figs. 23-25.) 



Shell tall and tapering, very solid, smooth and glossy, a little 

 contracted at the sutures, last whorl subangled at periphery; 

 sometimes decollate and plugged. Colour rusty red, yellow on 

 apex and between the ribs, with a faint, narrow, white peripheral 

 band. Whorls ten, counting the dome-shaped protoconch of two 

 and a half whorls. Suture deeply impressed, undulated by the 

 ends of the ribs. Sculpture : apex smooth, ribbing gradually 

 commences on the third whorl, increasing in strength but not in 

 number to the last. Ribs longitudinal, broad, curved, undulating, 

 ten on last whorl, twelve on penultimate, fading away on base. 

 Under the lens appear fine, dense, wavy scratches crossing both 

 ribs and interstices. Aperture fortified externally with a varix; 

 inner lip very thick, forming a free edge; anteriorly the aperture 

 contracts to a short, shallow, oblique spout. Operculum (figs. 24, 

 25) peltate, elevated, not spiral, apex excentric, from the apex a 

 furrow runs to the farthest margin, from the lower corner of the 



"^ Ann. Mag. Nat. Hist. (2), vii. 1851, p. 194. 



