Thii-asia.] GASTROPODA. f6o 



Epidermis thin, not shining. Spire conoidal. obtuse, its height about 

 two-thirds that of the aperture ; outlines almost straight. Protoconch 

 of 1| shining convex whorls. Whorls 5, convex, gradually increasing, 

 the last not descending, lightly angled at the periphery ; base convex. 

 Suture scarcely impressed. Aperture oblique, rotundly lunate. The 

 outer lip sometimes lightly angled. Peristome simple, acute, thin. 

 Columella short. Inner Up oblique, arcuate, slightly callous, reflexed 

 above, and spreading as an extremely thin whitish glaze over the 

 convex parietal wall. Perforation narrow, deep, about one-twelfth 

 of the minor diameter, sometimes partly hidden by the reflection of 

 the inner lip. 



Diameter Maj., 6-25 mm. ; min., 5 mm. : height, 3-75 mm. (type). 



Dentition. Hutton, T. N.Z.I., xiv, 151, pi. 3. f. B (erroneously 

 P. hypopolia) ; xvi. pi. ix, f. N. 



Jaw arcuate, rounded at the ends, vertically finely plaited. 



Raclula with the formula 26 +1 + 26; laterals 10 to 11. Central 

 tooth tricuspidate, with a prominent mesocone and 2 minute ecto- 

 cones. Laterals bicuspid, the inner cutting-point piomincnt and 

 long. Marginals broad, with 4 cutting-points, the inner two strongest 

 and sometimes coalesced. Last marginals bidentate. 



Type in the Canterbury Museum, Christchurch. 



// ab. Dunedin, type (Captain Hutton) ; Riccarton Bush, near 

 Christchurch ; Dyer's' Pass ; Little River (H. S.) ; Akarou (F. Suter) ; 

 Bealey. 



This species is confined to the South Island, and it is not common. 



Genus 8. PBENACOHELIX, Sutcr, 1892. 



rhenacohelix, Suter, T.N.Z.I., xxiv, 1891 (1892), 270. Type : P. Ponsonbyi, 

 Suter. Fruticicola, Hutton, 1884 ; not of Held. 



Animal elongate, the foot narrow, projecting behind the shell ; 

 mantle subcentral, rather anterior, included; eye - peduncles long, 

 rather clavate ; tentacles moderate, f'audal gland present. 



Jaw arcuate, with numeroiis fiat plaits indenting the concave 



margin. 



Radula with the central tooth small, with or without side cusps ; 

 laterals similar, lacking entocones ; marginals nnilti cuspid, the inni'r 

 cusp much larger. 



Shell depressed, namtwlv umbiiicated, the spire slightly convex 

 or c.onoidal. periphery broadly rounded ; whorls finely ribbed, the 

 protoconch smooth except for microscopic spiral stria 1 : aperture 

 lunate ; lip simple. 



Distribution. New Zealand. 



Remarks. The genus Rhytidopsis, Ancey, 1882. from New Caic 

 donia, seems to be nearly allied, perhaps identical, but it is not known 

 whether the animal has a caudal gland or not. The dentition seems 

 to be similar. 



