664 



GASTROPODA. 



KBV TO SPECIES. 



A. Shell subperforate, perforation nearly closed ; 8 riblets per 



millimetre . . . . . . , . . . . . chordata. 



B. Shell narrowly perforate, perforation more or less open. 



a. Perforation about one-twelfth of greatest diameter, open ; 



16 riblets per millimetre . . . . . . . . subantarctica. 



aa. Perforation about one-sixth to one-seventh of greatest 



diameter. 



b. Periphery obtusely shouldered ; riblets 6 per milli- 

 metre ; perforation one-sixth of greatest diameter, 

 partly covered . . . . leptalea. 



bb. Periphery rounded. 



c. Riblets 8 per millimetre ; height of spire one-half 

 that of aperture ; perforation 1 mm. ; white 

 within ; diameter of shell 6-8 mm. . . . . perplexa. 



cc. Riblets 9, rarely 8 or 7, per millimetre ; height 

 of spire two-thirds that of aperture ; perfora- 

 tion 0-5 mm. ; diameter of shell 3-5 mm. . . p-ilula. 

 C. Shell moderately umbilicated ; periphery angled above the 



middle. 



a. Riblets 8, rarely 7 or 6, per millimetre ; height of spire a 

 little more than one-third that of aperture ; umbilicus 

 one-fifth of greatest diameter . . . . . . Ponsonbyi. 



aa. Riblets 5 per millimetre, retractive ; whorls slowly in- 

 creasing ; height of spire a little more than half that 

 of aperture: umbilicus one-quarter of greatest diameter Stoke-si. 



1. Phenacohelix chordata, PfeifEer, 1862. Plate 26, fig. 5, a, b. 



Helix chordata, Pfr., Malak. Blatter, viii, 147 ; M.H. Viv., v, 72 ; Hector, 

 Cat. Land Moll. N.Z., 6. Soninu \Th<i~la$sia) chordata, Pfr., Nomencl. 

 Hel. Viv., 46. Patula chordata, Pfr. : Hutton, M.N.Z.M., 5. Fruticicola 

 chordata, Pfr. : Hutton, T.N.Z.I.. xvi, 194. Phenacohelix chordata, Pfr. : 

 Hedley and Suter, P.L.S. N.S. W. (2), vii, 642. Flammvlina (Phenacohelix) 

 chordata, Pfr. : Suter, J. de Conch., xli, 250. 



Shell very small, globosely turbinated, subperforate. thin and 

 fragile, not shining, semitransparent. Sculpture consisting of some- 

 what inequidistant cord-shaped radiate riblets, about 8 per milli- 

 metre ; the interstices with numerous fine microscopic growth-lines, 

 crossed by somewhat indistinct microscopic spiral lines, present also 

 on the protoconch, which otherwise is smooth. Colour light horn 

 marbled with fulvous, base usually tessellated. Epidermis very thin. 

 Spire convexly conical, somewhat sharp, its height the same as that 

 of the aperture. Proioconch arched, of li whorls. Whorls 5. convex, 

 the last slightly inflated at the base, periphery rounded. Suture im- 

 pressed. Aperture a little oblique, lunar. Peristome simple, straight, 

 margins remote. Columella short, vertical, somewhat arcuate. In mi- 

 lip slightly callous, somewhat reflected above over the very narrow 

 perforation. 



Diameter Maj., 3-75 mm. ; min., 3-6 mm. : height, 3 mm. 



Animal unknown. 



Type in the K.K. Hofmuseum, Vienna. 



