202 DISCOVERY REPORTS 



Height 8-5 mm.; diameter 3-5 mm. (Holotype). 



Habitat: Off Three Kings Islands, Sts. 933, 934, 92 m. 



The type of sculpture is very like that of Hedley's genus Stiva (1904), but the shell 

 is a typical Rissoina. 



This now becomes the largest member of the genus known from New Zealand 

 waters. It resembles Finlay's powelli, but differs in having twice as many axials. 



Rissoina achatinoides, n.sp. (Plate LIII, fig. 7). 



Shell elongate-conic, smooth and glossy. Apart from numerous faint axial growth 

 striae there is neither spiral nor axial sculpture. Whorls six, including a dome-shaped 

 protoconch of two smooth whorls; outlines straight. Spire tall, just twice height of 

 aperture. Aperture oblique, ovate, angled above and distinctly channelled at the base of 

 the columella. Outer lip slightly thickened, almost straight with side of spire. Columella 

 oblique, short and twisted. Colour buff on the apical whorls, deepening to a rich golden 

 brown on the two last whorls. The interior of the aperture is of the same golden brown 

 colour, but the calloused columella is white. 



Height 4-8 mm.; diameter i-8 mm. (Holotype). 



Habitat: Off Waikuku Beach, near North Cape, St. 930, 29 m. 



This is the only New Zealand Rissoina so far known that is entirely without both 

 spiral and axial sculpture. It is near to Odhner's achatina, but that species has 

 crowded faint spirals and an aperture of the chathamensis type. In achatinoides the 

 aperture is proportionately rather smaller and has the outer lip in line with the side 

 of the spire. 



Rissoina manawatawhia, n.sp. (Plate LIII, fig. 5). 



Shell small, very tall and slender, glossy and smooth except for very faint, almost 

 obsolete, spiral scratches. Apart from weak, fairly numerous and somewhat irregular 

 axial growth lines there is no true axial sculpture. Whorls six, including a dome-shaped 

 protoconch of two smooth whorls. Outlines slightly convex. Spire tall, about z\ times 

 height of aperture. Aperture small, oblique, ovate, angled above and channelled at base 

 of columella. Outer lip thickened, convex. Colour very pale rose pink with an indistinct 

 narrow white spiral zone just above the lower suture. 

 Height 3-7 mm.; diameter 1-4 mm. (Holotype). 

 Habitat: Off Three Kings Islands, St. 934, 92 m. 



This species is close to Finlay's fictor, from 38 fathoms off Cuvier Island, but differs 

 in the practically obsolete spiral sculpture and smaller size. The colour differs also, but 

 in this genus the coloration is so variable that it cannot be taken into account. 



The New Zealand Recent species of Rissoina are now as follows: (1) chathamensis 

 (Hutton, 1873) (= rngidosa, Hutton, 1873), (2) zonata, Suter, 1909, (3) rufolactea, Suter, 

 1908, (4) achatina, Odhner, 1924, (5) afignina, Finlay, 1926, (6) powelli, Finlay, 1930, 

 (7) fictor, Finlay, 1930, (S)fucosa, Finlay, 1930, (9) larochei, Finlay, 1930, (10) aupouria, 

 Powell, 1936, (11) manawatawhia, Powell, 1936, (12) achatinoides, Powell, 1936. 



