Sissoa.] GASTROPODA. 215 



slightly convex. Protoconch small, globose, of 1J smooth and convex 

 whorls. Whorls 5-5J, moderately convex ; base rounded. Suture 

 impressed, slightly channelled, margined by a thin thread ; the 

 sutural channel is very often continued on the body-whorl below the 

 periphery. Aperture vertical, oval, angled above. Peristome discon- 

 tinuous, sharp, not thickened. Basal lip slightly effuse. Columella 

 vertical, slightly concave, and callous ; a thin callosity on the parietal 

 wall. Opcrculum unknown. 



Diameter, 1-5 mm. ; height, 2-mm. 



Animal unknown. 



Type in my collection. 



Hab. Stewart Island, type (A. Hamilton) ; near the Bounty and 

 Snares Islands, in 50 fathoms, and Taumaki Island, South Island, 

 in 10 fathoms (Captain Bollons) ; Banks Peninsula (Iredale). 



27. Rissoa porcellana, Suter, 1908. Plate 13, fig. 2. 



Rissoa porcellana, Suter, P. Mai. S., viii, 30, pi. 2, f. 29. 



Shell minute, ovate, rimate, smooth, translucent white, whorls 

 faintly shouldered. Sculpture consisting of fine growth-lines, crossed 

 by a few microscopic spiral striae upon the base. Colour white. Spire 

 conical, faintly gradate, 1| times the height of the aperture ; outlines 

 but little convex. Protoconch small, globose. Whorls 4^ convex, 

 slightly shouldered, the last large ; base rounded. Suture not deep. 

 Aperture ovato-rotund, angled above. Peristome discontinuous, rather 

 sharp. Columella vertical, arcuate. Inner lip not expanded, spreading 

 as a thin callosity over the parietal wall. There is a distinct umbilical 

 chink. Operculum unknown. 



Diameter, 1-3 mm. ; height, 1-8 mm. 



Animal unknown. 



Type in my collection. 



Hab. Near the Snares, in 50 fathoms (Captain Bollons) ; Dusky 

 Sound, in 30 fathoms (E. Henry) ; dredged off Otago Heads (A. 

 Hamilton). 



28. Rissoa stewartiana, Suter, 1908. Plate 13, fig. 3. 

 Rissoa stewartiana, Suter, P. Mai. S., viii, 31, pi. 3, f. 30. 



Shell minute, ovate, rimate, smooth, and faintly shining. Sculp- 

 ture consisting of fine oblique growth-striae, crossed on the last whorl 

 by microscopic faint and distant spiral lines. Colour light horny ; 

 dead shells are whitish. Spire conical, a little higher than the aper- 

 ture ; outlines convex. Protoconch small, globose, of 1 smooth, white, 

 and shining whorls. Whorls 4J, convex, the last large ; base rounded. 

 Suture much impressed. Aperture oblique, oval, subangled above. 

 Peristome continuous, slightly thickened inside, sharp. Columella 



