GASTROPODA. [Pectinibranchia. 



through the aperture. Peristome not continuous, thin and sharp, 

 slightly effuse below. Columella oblique, nearly straight, but little 

 callous, subtruncate at the base. Operculum unknown. 



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



Animal unknown. 



Type in Mr. W. H. Webster's collection. 



Hob. Takapuna, type (W. H. Webster) ; Hohoura Bay (R. 

 Buddie). 



Sect. 3. ZEBINA, H. and A. Adams, 1854. 



Zebina, H. & A. Ad., G.R.M., i, 1854. 328 Type : R. Icevissima, C. B. 

 Adams. 



Shell white, solid, opaque, polished, smooth or partly striate ; 

 outer lip rather thick, often with 1 or more anterior internal 

 tubercles. 



KEY TO SPECIES. 



A. Surface smooth, sometimes with 4 spiral lines at the base ; aper- 



ture rounded anteriorly . . . . . . . . Coulthardi. 



B. Surface with microscopic spiral grooves ; aperture truncated at 



the base . . . . _ _ emarginata. 



6. Rissoina Coulthardi, Webster, 1908. Plate 13, fig. 13. 



Rissoina Coulthardi, Webster, T.N.Z.I., xl, 1907 (1908), 258, pi. 21, f. 30-32. 



Shell imperforate, milk-white, loosely coiled, especially the last 

 whorl, the aperture and its posterior callosity occupying exactly one- 

 half the entire length of the shell. Protoconch minute, shining, colour- 

 less. Whorls 5, somewhat flat, extremely glossy, the body-whorl 

 with a few longitudinal markings of pale brown ; in some specimens 

 these stripes are transparent. Suture shallow. Base of one speci- 

 men (not the type) with 4 spiral lines. Aperture pear-shaped ; a 

 heavy callus at the juncture with the body, and a partly concealed 

 arch in the angle. Columella nearly upright, with a wrinkled twist 

 on the outside of the pillar. Operculum unknown. (Webster.) 



Diameter, 1-5 mm. ; height, 3 mm. 



Animal unknown. 



Type in Mr. W. H. Webster's collection. 



Hob Orua Bay, Manukau Harbour, in 3 fathoms.^ 



I have not seen this species. 



7. Rissoina emarginata, Hutton, 1885. Plate 13, fig. 14. 



Rissoa emarginata, Hutt., T.N.Z.I., xvii, 1884 (1885). 320, pi. 18 f 20- 

 Plioc. M.. 05. pi. 8, f. 68; Iredale, T.N.Z.I.. xl. 383. Rissoina parvi- 

 hrata, Suter, T.N.Z.I., xxxix, 1906 (1907), 257. pi. !. f. 5. 



Shell small, oblong, imperforate, polished, microscopically spirally 

 hrate, base subtruncate. Sculpture formed by close, fine, spiral 

 grooves, visible only under a good lens, the interspaces being broader 

 than the grooves. Colour pure-white. Spire conical, about 1 times 

 the height of the aperture. Protoconch minute, smooth, globularly 



