The -isia. } 



GASTROPODA. 



655 



KEY TO SPECIES. 



A. Greatest diameter of shell not or not much more than 4 mm. ; shell 



with membranous plaits 



a. Shell subperforate, with microscopic spiral striae, peripheral 

 processes sharply pointed . . . . . . 



aa. Shell with a narrow open perforation, no microscopic spiral 

 stria?, peripheral processes rounded . . . . , . 



I'.. Greatest diameter of shell considerably more than 4 mm. 

 a. Periphery of shell sharply keeled. 



b. Microscopic spiral sculpture indistinct, height of spire equal 



to that of the aperture. Dimensions, 7 mm. by 4 mm. 



Mi. Microscopic spiral sculpture prominent, height of spire 



two-thirds that of aperture. Dimensions, 1H mm. by 



7i mm. . . . . . . . . . . 



an. Periphery of shell angled or subangled. 

 b. Shell radially ribbed. 



c. Shell with fine sharp riblets, 15 per millimetre. 



mensions, 6| mm. by 3 mm. . . 



cc. Shell with membranous deciduous riblets, 3-4 

 millimetre, sometimes only growth-stria tion, 



.Di- 



per 



dis- 



Celindt. 

 Tamora. 



antipoda. 

 Traversi. 



Valeria. 

 decidna. 



Ophelia.. 



tinctly microscopically reticulated. Dimensions, 

 9 mm. by 7 mm. . . . . . . . . 



'''. Shell not ribbed, but more or less distinctly obliquely 

 striated. 



c. Microscopic spiral sculpture indistinct, outlines of 

 spire convex, periphery but little angled. Dimen- 

 sions, 8 mm. by 4 mm. . . . . . . 



cc. Microscopic spiral lines exceedingly tine and dense, 

 strongly and irregularly striated, outlines of spire 

 nearly straight, periphery angled. Dimensions, 

 10} mm. by 7-8 mm. . . . . . . 



1. Therasia (?) antipoda, Hombron and Jacquinot, 1854. Plate 26, 

 fig. 2, a, b. 



Helix antipoda, H. \- J., Voy. P.S., v, 18, pi. 6, f. 13-16: Pfeiffer, M.H. 

 Viv., iv, 111; Hector, Cat. Land Moll. N.Z., 15; Button, M.N.Z.M.. 

 19. Nanina (Thalassia) antipoda, H. & J., Nomencl. Hel. Viv., 47. 

 Ckaropa (Thalassia) .dandice antipoda, H. & J. : Tryon, Man. Concb,, 

 (2), ii, 214, pi. 03, f. 65-67. Thalassia neozelanica antipoda, H. & J. : 

 Hutton, T.N.Z.I., xvi, 204; HedJey and Suter, P.L.S. N.S.W. (2), vii,. 

 637. Flammnlinn (Thalassia) zelandice antipoda, H. & J. : Suter, 

 .1. de Conch., xli, 255. Helix aucklandica, Le Guillou, Revue Zool., v, 

 1842, 140; Pfeiffer, M.H. Viv., i, 119. H. (Thalassia) aucklandica, 

 Le Guill. : Hector, Cat. Land Moll. N.Z., 15. Nanina (Thalassia) auck- 

 landica, Le Guill., Nomrncl. Hoi. Viv., 47. Helix aucklandica, Le Guill. : 

 Hutton, M.N.Z.M., 19. Thalassia neozelanica aucklandica, Le Guill. : 

 Hutton, T.N.Z.I., xvi, 204. Charopa (Thalassia) zelandice aucklandica, 

 Le Guill. : Tryon, Man. Conch. (2), ii, 214. Thalassohelix (?) auck- 

 landica, Le Gniil. : Hodley and Suter, P.L.S. N.S.W. (2), vii, 637. Flam- 

 iiiiilinn (ThtiliixxniK'il.i-) aucklandica, Le Guill. : Suter, J. de Conch., xli. 

 255. 



Shell small, orbicularly conoidal. umbilicated, striated, shining, 

 thin and semitransparent, periphery keeled. Sculpture : Protoconch 

 indistinctly microscopically spirally striate ; the following whorls with 

 inequidistant and very unequal oblique radial stria 1 and plaits ; the 



