334 



GASTROPODA. 



[Pectinibranchia . 



Subgen. 1. ODOSTOMIA, s. str. 



Shell without axial sculpture, spiral sculpture absent, or, if present, 

 microscopical, polished ; whorls not tabulated, not inflated ; peri- 

 treme discontinuous. Type : 0. plicata. Mont. 



KEY TO SPECIES. 



A. Spire of about the same height as the aperture. 



a. With distinct dense microscopic spiral striae . . . . denselirata. 



aa. With a few indistinct microscopic spirals on the body- 

 whorl, spire scalar, last whorl very high . . . . dolichostoma. 

 aaa. Without spiral sculpture, spire not scalar . . . . cryptodon. 



B. Spire about H times the height of the aperture, with indistinct 



spiral microscopic striae, suture margined. 

 . Adult with 6 to 8 whorls, body-whorl angled, suture 



narrowly margined. 

 b. Adult with 6 whorls ; height. 4'5 mm. . . . . stygia. 



bb. Adult with 8 whorls ; height, 7'5 mm. ; spire 



broadly conical . . . . . . . . bembix. 



mi. Adult with 5 whorls, bodj'-whorl rounded, suture broadly 



margined . . . . . . . . . . taumakiensis. 



C. Spire about twice the height of the aperture. 



a. Without any spiral sculpture. 

 b. Spire subulate. 



c. Suture impressed, narrowly margined . . inornntn. 



cc. Suture channelled, whorls angular above the 



suture . . . . . . . . pudica. 



bb. Spire conical. 



c. Spire lightly scalar, umbilicus closed . . . . hyphala. 



cc. Spire not scalar, last whorl subangular, um- 

 bilicus narrow but distinctly open . . takapunaensis. 

 <in. With a few irregular microscopic spiral striae. 



b. Spire subulate, suture shallow . . . . . . vestalis. 



bb. Spire conical. 



c. Body-whorl rounded . . . . . . Murdochi. 



cc. Body-whorl acutely angled .. .. .. acutangula. 



D. Spire about 2^ times the height of the aperture, with a fine 



groove on periphery of body-whorl . . . . . . incidata. 



E. Spire more than three times the height of the aperture, sub- 



cylindrical, without sculpture . . . . . . fastigiata. 



1. Odostomia acutangula, Suter, 1908. Plate 16, fig. 14. 



Odostomia actuangula, Suter, T.N.Z.I., xl, 1907 (1908), 366, pi. 29, f. 13. 



Shell minute, elevated conic, rimate, solid, polished. Sculpture 

 consisting of a few microscopic spiral stripe, crossed by vertical flexuous 

 fine growth-lines. Colour white. Spire elevated conic, about twice 

 the height of the aperture ; outlines straight. Protoconch hetero- 

 strophe, oblique, small and rounded, of 1 whorl. Whorls 5, regu- 

 larly increasing, flatly convex, the last acutely angled at the periphery ; 

 base flat. Suture impressed between the upper whorls, channelled 

 further down. Aperture subvertical. broadly oval, angled above and 

 effuse below. Outer lip nearly straight, acutely rounded on meeting 

 the basal lip, which is straight. Columella vertical, very little arcuate. 



