Risellopsis.} GASTROPODA. 191 



Shell trochiform or depressed turbinate, solid, periphery ungulate 

 or carinate, base more or less concave, perforate or imperforate. Aper- 

 ture broadly oval or rhomboidal. Peristome sharp, porcellanous in- 

 side. Operculum oval, corneous, subspiral, nucleus excentric. 



This family includes the genera Risella, Gray, and Risellopsis, 

 Kesteven. 



Distribution. Australasia. 



Genus 1. RISELLOPSIS, Kesteven, 1902. 



Risellopsis, Kes., Rec. A.M., iv, No. 7 (25, viii), 1002, 319. Type : Fos- 

 sarina varia. Hutton. 



Shell comparatively small, stomatiform or depressed trochoid, per- 

 forate, rather solid, spirally ribbed or carinated, growth striate ; 

 aperture oval, oblique, interior porcellanous ; outer lip sinuated ac 

 cording to sculpture ; columella short, curved ; operculum corneous, 

 subspiral. 



Distribution. New Zealand, Tasmania, and Australia. 



1. Risellopsis varia, Button, 1873. Plate 35, fig. 13. 



Adeorbis varius, Hutt., C.M.M., 35. Risella (?) varia. Hutt., J. de Conch., 

 1878, 27. Fossarina varius, Hutt., M.N.Z.M., 79. Risellopsis varia, 

 Hutt. : Kesteven, Rec. A.M., iv, 320, f. 30-32 in text. 



Shell rather solid, small, opaque with translucent spaces, turbinate, 

 perforate. Sculpture : Superiorly there are 2 spiral riblets, the first 

 and smaller at a short distance from the suture, the other median ; 

 there are 2 equal-sized riblets on the periphery, the lower of which 

 is seen just above the suture, on the whorls of the spire ; upon the 

 base there are 3 equal ribs, and a smaller one around the umbilical 

 tract ; oblique dense growth-lines cross the riblets and interstices, 

 more distinct on the base. Colour brown, irregularly varied with 

 yellow and grey ; umbilical tract white. Epidermis solid, not shining. 

 Spire conoidal, about the same height as the aperture, outlines slightly 

 convex. Protoconch of 2 whorls, smooth, flatly convex. Whorls 4J, 

 first slowly, then more rapidly increasing, rounded ; base flatly con- 

 vex, with concave umbilical area. Suture impressed. Aperture slightly 

 oblique, broadly oval, interior dark purple with a few white lines. 

 Peristome sharp, sinuated by the spiral riblets, margins approximating. 

 Columella short, arcuate, white. Inner lip reflexed over the narrow 

 perforation, and spreading as a very thin glaze over the parietal wall. 

 Operculum horny, oval, subspiral. 



Diameter Maj., 8-5 mm. ; min., 7 mm. : height, 4-7 mm. 



Dentition. The central tooth is bluntly unicuspid. base broad. 

 The first lateral with 3 blunt cusps, the middle one broadest ; the 

 second has an outer cusp, and ends in a long curved and pointed 



