.ttiliscus.'] GASTROPODA. 643 



Whorls 5-5|, regularly increasing, rather convex, the last not descend- 

 ing, rounded ; base convex, depressed in the centre. Suture well im- 

 pressed. Aperture oblique, lunate. Peristome thin, straight, the 

 margins slightly approaching. Colwnella short, oblique, slightly 

 arcuate. Inner lip lightly callous and reflected above, extending 

 broadly as a thin white and smooth callus over the convex parietal 

 wall. Umbilicus deep, narrow, about | mrn. in diameter. 



Diameter Maj., 5 mm. ; min., 4-25 mm. : height. 2-8 mm. 



Dentition is that characteristic of the genus. 



Type, in Mr. R. Murdoch's collection, unfortunately destroyed by 

 fir i . Co-types in my collection. 



Hob. North Island : Wanganui ; Cape Egmont ; Toko, near 

 Stratford ; Manawatu (R. Murdoch) ; near Auckland (Captain 

 Hutton) ; Mount Pirongia (T. Urquhart) ; Heretaunga ; Dannevirke 

 ( Brooks) ; Otaki Gorge (H. B. Preston) ; Midhirst (Young) ; Forty- 

 mile Bush (H. S.) ; Wellington. South Island : Kenepuru (Mc- 

 Ma.hon) ; Dyer's Pass ; Riccarton Bush (H. S.) ; Owaka. Clutha. 

 (Bryant). 



Remark. -The shell resembles that of Phenacohelix Ponsonbyi, 

 Suter. 



9. Allodiscus planuiatus, Hutton, 1883. Plate 25, fig. 14, a, b. 



Charopa planulata, Hutt., N.Z.J.S., i, 1883, 477 ; T.N.Z.I., xvi, 181. Psyra 

 planulaia, Hutt., i.e., 202. Gerontia (Allodiscus) planulata, Hutt. : 

 Pilsbry, Man. Conch. (2), viii, 67. Allodiscus planuiatus, Hutt. : Heclley 

 and Suter, P.L.S. N.S.W. (2), vii, 638. Flammulina (Allodiscus) planu- 

 lata, Hutt. : Man. Conch. (2), ix, 15, pi. 3, f. 4r-6 ; Suter, J. de Conch., 

 xli, 252. 



Shell small, depressed, subperforate or imperforate, very closely 

 ribbed, rather shining, thin, translucent. Sculpture : Protoconch 

 microscopically distinctly spirally striate ; the following whorls with 

 fine slightly undulating radial riblets, 20 to 25 per millimetre ; in- 

 terstices with fine growth-lines, reticulated by microscopic spiral 

 striae. Colour horny-brown, sometimes streaked and clouded with 

 rufous. Epidermis thin, membranous, but lightly shining. Spire 

 flatly convex, about one-fourth the height of the aperture. Proto- 

 conch of 1| lightly convex whorls, flattish. Whorls 4| to 5, slowly 

 increasing, convex, periphery and base rounded, the latter impressed 

 in the middle. Suture impressed. Aperture subvertical, broadly 

 rotundly lunar. Peristome thin, simple, sharp. Columella very short. 

 Inner lip lightly callous and reflexed above, extending broadly as a 

 very thin white glaze over the convex parietal wall. Umbilical per- 

 f< tration very narrow, partly open or covered over by the reflected 

 inner lip. 



Diameter Maj., 3-75 mm. ; min., 3 mm. : height, 2 mm. ; 



Dentition. Hutton, T.N.Z.I., xvi, 181, pi. 9, f. J. 



Radula having the formula 11 + 1 + 11 ; laterals 4. One speci- 

 men had only 9+1 + 9 teeth. Central tooth with a short tricuspid 

 21* 



