Obex denselirata (Suter). (Fig. 17.) 1907. Odostomia denselirata Suter, Trans. N.Z. Inst., vol. 40, p. 364, pl. 28, fig. 9. 1913. Odostomia denselirata Suter, Manual N.Z. Moll., p. 336, pl. 16, fig. 17 (Atlas). Suter gives a good description, but his rather distorted figure in the Atlas does not show the whorls sufficiently shouldered, and inaccurately represents the base as excavated towards the columella. The spirals can just be picked up in a good light by means of a hand-lens. Height, 2·1 mm.; width, 1·2 mm. (holotype). Locality: off Little Barrier Island, in 20 fathoms. Type and a paratype in Wanganui Museum. Obex granum n.sp. (Fig. 18.) Shell very small, outlines a little convex; body-whorl long, its height two-thirds to three-quarters that of shell. Spire-whorls lightly convex, body-whorl flattish above periphery; sutures distinctly cut in. Protoconch considerably depressed, no lateral nucleus evident. Base long, lightly convex; aperture long, narrowly pyriform; basal lip narrowly rounded; outer lip long, straight when viewed laterally; columella not heavy, arcuate, a horizontal plait at insertion. Surface rubbed, but microscopic spiral threads can be seen in several places. Height, 1·8 mm.; width, 0·95 mm. Locality: Kaawa Creek (Waitotaran). Type (unique) in writer's collection. Genus Striodostomia nov. Type: Striodostomia orewa n.sp. Typical Striodostomia has an embryo of helicoid coiling and universal Strioturbonilla-like striations. There is no axial sculpture. It is a different build of shell from other Neozelanic Odostomia, and a search through literature has failed to yield an already existing group for it. It has a long, narrow body-whorl with long base, narrowly elongated aperture, convex outline with sharp tip to spire, and channelled suture. Key to Species of Striodostomia. Striations seen under hand-lens; body-whorl moderately high in relation to width; growth-lines inconspicuous. Columella-fold low, wide, weak; shell of moderate size. Outline distinctly convex; spire broad; suture well channelled. orewa Outline convex above, straighter below; spire more attenuate; suture not so distinctly channelled. locuples Columella-fold distinct, sharply elevated; shell small. kaawa Striations much fainter, not well developed; plait hardly differentiated externally; body-whorl much narrower and higher; growth-lines conspicuous, irregular. waikaia Striodostomia orewa n.sp. (Fig. 11.) Shell of moderate size, bi-conic, height of spire half that of shell, outlines of spire convex. Post-nuclear whorls 4 in number, convex, closely tabulated at summits; suture very distinct, channelled. Protoconch small, heterostrophic, in a low helicoid spiral; nucleus about one-half immersed. Sculpture of numerous fine, wavy spiral striations,