A Review of the Tertiary and Recent Neozelanic Pyramidellid Molluscs. No. 7—Further Odostomid Genera.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 70, 1940-41, Page 150

A Review of the Tertiary and Recent Neozelanic Pyramidellid Molluscs. No. 7—Further Odostomid Genera. By C. R. Laws., d.sc, Auckland. [Read before the Auckland Institute, February 19, 1940; received by the Editor, February 26, 1940; issued separately, September, 1940.] Genus Agatha A. Adams. 1860. A. Adams, Ann. Mag. Nat. Hist., 6, p. 422. Type (fide Dall and Bartsch): Pyramidella (Agatha) virgo A. Adams.* See fig. 6. Adams subsequently (1861) changed Agatha to Myonia, but his reason for doing this is unknown, since Dall and Bartsch state that the earlier name is not preoccupied. Myonia, however, is preoccupied, and it was renamed Amathis in the same year, and also Adelactaeon by Cossman, 1895. Agatha covers very well indeed certain large Odostomia from New Zealand, and the figure of A. virgo, the genotype (Proc. U.S. Nat. Mus., vol. 30, p. 335, pl. 18, fig. 2; 1906), shows that species to be remarkably similar to O. alexanderi Marwick, a fossil from the Duntroonian beds at Chatton. The generic features of Agatha are: large size; high body-whorl with elongated, subovate aperture; strong suture, sometimes almost channelled; oblique, arcuate pillar with a strong plait entering aperture spirally at a high angle. The base becomes depressed alongside the pillar to form a furrow which leads towards a very narrow umbilical chink. The subangulation on the periphery of the last whorl, present in the genotype, is also quite typical of the Neozelanic species, and is no doubt also a character of generic significance. The same applies to the effuse nature of the basal lip near its junction with the columella. Key to Neozelanic Species of Agatha. Adult shell large, not less than 9.0 mm. high. Sutures margined. Spire sharpened, its outline faintly concave; whorls closely staged; body-whorl broadly convex, not angled. otaioensis Spire not sharpened by concave outline; whorls not staged; body-whorl sub-angled at periphery. georgiana Sutures not margined. Whorls distinctly though narrowly staged; pillar considerably excavated; plait strong. alexanderi Adult shell smaller, less than 9.0 mm. high. Apex blunter than usual, embryo more convex on summit; growth-plications obvious; suture distinctly closely submargined. pittensis

Agatha georgiana (Hutton). (Fig. 3.) 1885. Odostomia georgiana Hutton, Trans. N.Z. Inst., vol. 17, p. 319, pl. 18, fig. 16. 1893. Odostomia georgiana Hutton, Macleay Mem. Vol., Plioc. Moll., p. 57, pl. 7, fig. 49. * The full synonymy is given in the Manual of N.Z. Mollusca, p. 335.1908. Odostomia bembix Suter, Trans. N.Z. Inst., vol. 40, p. 362, pl. 28, fig. 6. 1908. Odostomia inornata Suter, Trans. N.Z. Inst., vol. 40, p. 364, pl. 28, fig. 8; Man. N.Z. Moll., p. 338, pl. 16, fig. 22 (Atlas), 1913. 1913. Odostomia stygia Suter, Man. N.Z. Moll., p. 339, pl. 16, fig. 23 (Atlas); O. marginata Murdoch and Suter, Trans. N.Z. Inst., vol. 38, p. 296, pl. 25, fig. 37, 1905; not of C. B. Adams, 1852. 1915. Odostomia (Oceanida) georgiana Hutton, Suter, N.Z.G.S. Pal. Bull., no. 3, p. 15. Hutton's drawing is of little use; it shows the spire too attenuate posteriorly, the body-whorl too full over the base, and it does not represent the aperture precisely. His description is meagre, and his statement that the shell lacks spiral sculpture is incorrect; this error Suter rectified (1915) in re-describing the species at greater length. Suter's reference to Oceanida must be negatived. The holotype has several naturally repaired fractures, and these apparently Suter mistook for varices. Further, Oceanida lacks spiral ornamentation. Protoconch small, heterostrophic, coiled in a low helicoid spiral; nucleus small, about two-thirds immersed on an average, but degree of immersion slightly variable. Height, 14·5 mm.; width, 6·0 mm. (holotype). Localities: Castlecliff, Wanganui (Castlecliffian), type; Eskdale, Petane ((Nukumaruan); Nukumaru; junction Ruakakapatuna and Makara Streams, South Wairarapa (Pliocene); Awanui Heads, in 12 fathoms; Dunedin Harbour; Poor Knights, in 60 fathoms (juvenile); Auckland Harbour; Stewart Island; off Otago Heads, in 50 fathoms. Type and four paratypes in Canterbury Museum, Christchurch. Finlay (Trans. N.Z. Inst., vol. 57, p. 405; 1926) has stated that O. bembix Suter is a synonym of O. georgiana Hutton, and comparison of the types confirms this conclusion. The same writer (loc. cit., p. 405) stated his belief that possibly O. stygia Suter is also a synonym of georgiana, but refrained from uniting them as he had not seen the type of stygia. Comparison of the holotypes substantiates Finlay's suspicion that these two forms are conspecific. The holotype of stygia is not adult. O. inornata Suter from Snares Islands must also fall in synonymy to georgiana Hutton. The holotype of inornata is a little more attenuate than typical georgiana and it has a weaker plait on the pillar, but the half-dozen paratypes show these features to be inconstant, and they approach very closely indeed to undoubted specimens of georgiana from off Otago Heads. Suter is incorrect in his statement (key to species, Manual, p. 334) that there is no spiral sculpture. The type has its surface poorly preserved, but good paratypes show fine but distinct microscopic spirals.

Agatha pittensis (Marwick). (Fig. 4.) 1928. Odostomia pittensis Marwick, Trans. N.Z. Inst., vol. 58, p. 484, fig. 126. Marwick compared his species with O. stygia Suter, which herein is united in synonymy with O. georgiana Hutton. It is distinguished from stygia, he states, in having straight sided whorls. The type of stygia, however, also has straight sided whorls, and the error is no doubt to be ascribed to Suter's poor figure in the Atlas. Pittensis is extremely close to the type of stygia, and can be separated from it and from georgiana only by the lack of spiral sculpture (other than the subsutural border), by the presence of very pronounced growth-plications which appear like obsolete axial ribbing, and by its heavier, more swollen embryo. In proportions and build of shell there is no difference. The unique holotype of pittensis is probably not an adult shell. Height, 6 mm.; width, 2·5 mm. Locality: Whenuataru Peninsula, Pitt Island, Chatham Islands. Type in collection of N.Z. Geological Survey, Wellington. Agatha alexanderi (Marwick). (Fig. 1.) 1929. Odostomia alexanderi Marwick, Trans. N.Z. Inst., vol. 59, p. 919, fig. 60. The holotype consists of the last two whorls of a large shell. The species is not uncommon in the sands at Chatton, the type locality. A. alexanderi is one of our large Odostomias, and it is characteried by an obviously elongate-oval body-whorl, very strong pillar-plait, and rather stepped spire. The growth-lines are strong and easily seen by the naked eye. Microscopic, low, wavy spirals are present over the later few whorls; suture not margined below. The protoconch is heterostrophic, the nucleus a little projecting laterally (helicoid) and about one-half immersed. Height, 12·0 mm.; width, 4·5 mm. (a topotype). Locality: Chatton, near Gore, Southland (Duntroonian). Type in collection of New Zealand Geological Survey, Wellington. The strong similarity to the genotype, a Recent species from Japan, has already been commented on in the remarks introducing the genus. Agatha otaioensis n.sp. (Fig. 2.) Shell of moderate size, elevated, conic, height of spire about half that of shell, its outlines faintly concave due to sharpening above (in this respect it is reminiscent of Hutton's bad figure of georgiana). Post-nuclear whorls 7 ½, flat to very faintly convex; suture only a little impressed, sometimes slightly clasping on last whorl. Protoconch small, high, heterostrophic, well tilted, coiled in a low helicoid spiral; nucleus about one-half immersed. Sculpture of fine, dense, wavy, spiral striae seen only on a good surface; suture margined below; periphery sub-angled, and one or two weak, widely spaced spirals on base; growth-lines distinct. Body-whorl high, flattish above, convexly sub-angled at periphery, base fairly full, convex,

spirally furrowed in region of columella; aperture subovate, drawn down and inwards towards axis of shell; columella set vertically, arcuate, its fold below insertion, strong and prominent; basal lip a little expanded; inner lip callused; outer lip broken back. Height, 9·0 mm.; width, 3·5 mm. (holotype). Locality: Blue Cliffs, Otaio River, South Canterbury (Hutchinsonian). Type in writer's collection. A. alexanderi has not the concave outline to spire, which is not so sharpened posteriorly, and possesses whorls rather more convex and narrowly tabulated at summits, so that the spire is somewhat staged and the sutures much more distinct. A. pittensis is a smaller and stouter species with heavy and less exsert protoconch, stronger and more regular growth-lines, and with spire, shape of whorl and suture similar to those of alexanderi. With the exception of the protoconch, similar characters separate georgiana from this Blue Cliffs species. Genus Evelynella nov. Type: Evelynella venustas n.sp. Herein are placed Odostomia-like shells having lirations on the internal side of the outer lip and an embryo of helicoid coiling. In New Zealand the group is not represented in the Recent fauna, but is conspicuous in the Upper Oligocene (Hutchinsonian) and in the Lower Miocene (Awamoan). Two species occur in the Lower Pliocene beds at Kaawa Creek (Waitotaran). There is a peculiar look about these shells due to the form of the body-whorl and aperture (particularly the rather disproportionate width of the former), which frequently enables one to pick this genus before inspecting the lip for lirations. Evelynella venustas n.sp. (Fig. 19.) Shell very small, conic, of about 4 ½ post-nuclear volutions, last whorl disproportionately swollen and less than one-half height of shell; outlines of spire straight to very lightly convex. Whorls very flatly and evenly convex, not or only very slightly shouldered; suture moderately impressed. Protoconch heterostrophic, of about 1 ½ volutions coiled in a helicoid spiral; nucleus one-half immersed. Sculpture of one incised spiral line a little posterior to suture and passing out over periphery of body-whorl and marking a slight angulation on whorls; growth-lines microscopic and densely packed together. Body-whorl of adults disproportionately inflated, the angulation practically absent; periphery broadly and evenly rounded; base convex. Aperture pyriform; columella vertical, arcuate, its plait posterior, pronounced, horizontal; umbilical chink present in some specimens; outer lip thin, straight, with a number of lirations some distance within. Height, 3·1 mm.; width, 1·2 mm. (holotype). Localities:—North Otago Awamoan horizons: shell-bed. Target Gully, Oamaru; Awamoa Creek, Oamaru; Pukeuri, near Oamaru. South Canterbury Awamoan horizons: White Rock River; Sutherlands, Tengawai River; Opihi River, three miles above its confluence with Tengawai River; Holme Station, Pareora Gorge. Also from

Clifden, Southland, in bands 4, 6A, 6C (type), and the new road-cutting behind the racecourse, which is the equivalent of band 7 of the beds along the Waiau River (all these Clifden occurrences are Hutchinsonian). Type in Auckland Museum (ex writer's collection). The shells from Clifden are on the whole somewhat stouter than the North Otago and South Canterbury ones; but some of them grade towards those from the more northern localities. Evelynella sinemacula n.sp. (Fig. 16.) Shell very small, massive for its size, narrowly conic, of 3 ¾ post-nuclear turns, the spire half the height of the shell, its outlines straight. Whorls very flatly and evenly convex, not shouldered; suture not much impressed. Protoconch heterostrophic, of about two volutions coiled in a pronounced helicoid spiral and frequently rather overhanging first adult whorl; nucleus on an average one-half immersed; the embryo as a whole is rather exsert compared with that typical of Odostomia. Sculpture of minutely fine microscopic incised lines (seen only here and there on some specimens) densely packed together. Body-whorl rather long, narrow, its whole outline gently and evenly convex; periphery widely rounded; base long and retreating slowly to axis of shell. The otherwise narrowly pyriform aperture is broken into by a very prominent fold at posterior end of columella, above which there is a wide channel trending obliquely out on to the base of the shell. There is one low, wide denticle near the posterior angle of the aperture. Outer lip (of a paratype) thin, faintly convex. Height, 3·0 mm.; width, 1·0 mm. (holotype). Locality: Chatton, near Gore, Southland (Duntroonian). Type in Auckland Museum (ex writer's collection). The single liration of the outer lip distinguishes this species. Evelynella marginalis n.sp. (Fig. 9.) Shell small, conic, of 5 post-nuclear whorls, spire a little over twice height of aperture, outlines straight. Whorls very flatly convex margined by a narrow, faintly tumid band behind. Protoconch heterostrophic, helicoid; nucleus less than one-half hidden in first adult volution. Sculpture of two microscopic incised spiral lines, one immediately anterior to swollen subsutural margin, the other slightly posterior to suture; growth-striae microscopic, densely packed together. Body-whorl not long, periphery well rounded, base lightly convex; aperture subovate, rounded in front, angled behind; columella set vertically, arcuate; columella-fold posterior, prominent, horizontal; outer lip thick, broken back, a number of lirations some distance within it. Height, 3·2 mm.; width, 1·4 mm. (holotype). Localities:—Kaawa Creek (Waitotaran), type; Clifden, Southland, new road-cutting behind racecourse = band 7 of the beds along the Waiau River; also bands 6A, 6C, 6D, 7A (all Hutchinsonian), and band 8A (Awamoan); Pourakino, Riverton, Southland. Type in writer's collection. The margined suture is distinctive.

Evelynella doliella n.sp. (Fig. 13.) Shell small, conic, of 5 ½ post-nuclear whorls, spire three times height of aperture, its outlines convex. Whorls flat, margined by a swollen band behind, causing spire to appear staged. Protoconch heterostrophic, helicoid; nucleus about one-half hidden in first adult volution. Sculpture of two microscopic incised spiral lines, one immediately anterior to swollen subsutural margin, the other slightly posterior to suture; growth-lines microscopic, densely packed together. Body-whorl not long, sub-angled, flat above periphery; base lightly convex. Aperture rhomboidal, broadly rounded in front, angled behind; columella set vertically, considerably arcuate; columella-fold posterior, prominent, horizontal; outer lip thin, straight, a number of lirations within. Height, 4·0 mm.; width, 1·5 mm. (holotype). Locality:—Clifden, Southland, band 6C and left side of Waiau River, bed C = base of band 7 on right side (type). Hutchinsonian. Type in Auckland Museum (ex writer's collection). Distinct from marginalis in having a higher and staged spire, whorls tumid posteriorly, angulated body-whorl and weaker plait. Evelynella kaawa n.sp. (Fig. 12.) Shell small, stumpy, of 4 ½ post-nuclear whorls, height of spire about 1 ¾ times that of aperture, its outlines straight to lightly convex. Whorls flat; suture narrowly but distinctly cut in. Protoconch of low helicoid coiling, its lateral nucleus a little less than one-half immersed. Subsutural border very lightly swollen; suture margined on each side by an incised spiral line; growth-lines straight, vertical. Height of body-whorl slightly over one-half that of shell; periphery sub-angled; base lightly convex. Aperture pyriform; columella fairly heavy, arcuate, set vertically; plait strong, situated slightly below insertion; inner lip turned in to suture at posterior of aperture; lirations weak, four or five in number, situated some distance in from edge of lip. Height, 2·5 mm.; width, 1·3 mm. Locality: Kaawa Creek (Waitotaran). Type in writer's collection. Nearest to E. doliella, but has border less swollen and is less attenuate. Genus Obex nov. Type: Odostomia denselirata Suter. This name has been provided for Odostomia denselirata Suter and a new species from Kaawa Creek, which are distinct from all other Odostomids in that their spiral sculpture consists of dense, regular, microscopic, distinctly raised threads (not striae) over the whole surface of the shell. The protoconch is heterostrophic and of low helicoid coiling.

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,

visible under hand-lens and of the order of intensity typical of Strioturbonilla amongst Turbonillids. Body-whorl half height of shell, high, evenly convex throughout in one broad sweep, the periphery much more widely rounded than usual in Odostomia, and the base long and slowly retreating to axis of shell; aperture narrowly subovate, sharply angled behind, rounded (not widely) in front; columella set vertically, distinctly arcuate, a broad low swelling just below its insertion; inner lip long, apparently not callused; outer lip thin, straight. Height, 4·5 mm; width, 1·5 mm. (holotype). Localities:—Orewa Beach, 20 miles north of Auckland (type); Takapuna Beach, Auckland; Oneroa, Waiheke Island. Type in writer's collection. The general build of this species, especially its long body-whorl of evenly convex outline, and its channelled suture, and the long narrow aperture with ill-differentiated plait, are important separative features. Striodostomia waikaia n.sp. (Fig. 15.) Shell of moderate size, considerably elevated, narrow. Apex and earlier post-nuclear whorls decollated, only the last three whorls remaining. Height of whorl greater than width, lightly and evenly convex, closely tabulated (almost channelled) at summits; suture distinct and greatly impressed. Spiral sculpture of faint microscopic striae, visible only in a good light here and there. Body-whorl long, flatly convex above; periphery low and bulging; base full, convex; aperture filled with hard matrix, fairly narrowly subovate, angled behind, rounded in front; columella set vertically, arcuate, its fold not in evidence; outer lip broken back; inner lip narrowly and lightly callused. Dimensions of body-whorl: height, 3·1 mm.; width, 2·6 mm. Locality: Waikaia (Ototaran). Type (unique) in Auckland Museum (ex Finlay collection). Waikaia can be distinguished from orewa by its weaker plait, higher and narrower body-whorl, and much fainter spirals. Striodostomia kaawa n.sp. (Fig. 14) Shell quite small, elevated, height of spire over twice that of aperture, outlines of spire lightly convex. Post-nuclear whorls five in number, flattish, cut in to suture; suture distinct, slightly channelled. Protoconch small, heterostrophic, typical of the genus. Spiral sculpture similar to that of the genotype. Height of body-whorl less than one-third that of shell, periphery low down. Aperture rather narrow; columella short, very arcuate, with a strong fold at insertion; inner lip thin, sharp, very faintly convex. Height, 2·8 mm.; width, 0·9 mm. Locality: Kaawa Creek (Waitotaran). Type in writer's collection. Distinguishable by much smaller size and distinct fold on columella. This is the species referred to as “n.gen. B n.sp.” in the list of Pyramidellids from Kaawa Creek (Trans. Roy. Soc. N.Z., vol. 66, p. 112, 1937). Very much better material has since been collected.

Striodostomia locuples n.sp. This species is intermediate between S. orewa and S. kaawa. It is larger than kaawa, but does not quite attain the size of orewa. In shape and outline it approaches kaawa closely, not having the broad spire and convex outline of orewa; but in features of aperture it is very similar to orewa, the plait being weak, not strongly projecting like that of kaawa. Fine microscopic striations present. Height, 4·2 mm,; width, 1·5 mm. Locality: Napier-Wairoa road, near Devil's Elbow. Type and many paratypes in writer's collection. A figure of this species will be given in the next paper of this series. Genus Scalenostoma Deshayes. 1863. Cat. Moll. Ile de la Réunion, pp. 58–60. Type (fide Dall and Bartsch): Scalenostoma carinatum Deshayes. Scalenostoma is for Odostomias lacking axial ornament and having a more or less strongly keeled periphery and flattish whorls. In the New Zealand species referred here the embryo is coiled in a distinct helicoid spiral, but no information relating to the coiling of the apical whorls of the genotype has been available. Scalenostoma southlandica n.sp. (Fig. 5.) Shell small, conic, spire moderately elevated, but degree of elevation rather variable, on an average about 2 to 2 ½ times height of aperture; outlines straight. Post-nuclear whorls 5 to 6 in number, quite flat, the keeled periphery closely overhanging suture. Protoconch small, heterostrophic, considerably sunken, in a pronounced helicoid spiral of about 2 ½ volutions; nucleus small, about one-third immersed. Axial sculpture absent; spiral sculpture of faint, irregular microscopic striations, a low, ill-defined subsutural spiral margination and a strong peripheral keel. Body-whorl short, flat above, the angulated periphery strongly keeled, base short and flattish; aperture quadrate, angled behind, broadly rounded in front; columella thick, set vertically, distinctly arcuate, with a light fold at its insertion; inner lip has a thin, narrow callus; outer lip thin, sharp, straight, descending almost vertically. Height, 3·4 mm.; width, 1·2 mm. (holotype). Localities: Clifden, Southland, bands 6C (type), 6A, and bed A on left side of river = band 6C on right side (Hutchinsonian). Type in Auckland Museum (ex writer's collection). The strength of the peripheral keel shows slight variation. Genus Gumina Finlay. 1928. Trans. N.Z. Inst., vol. 59, p. 260. Type (original designation): Odostomia dolichstoma Suter. In his definition of this genus Finaly (Trans. N.Z. Inst., vol. 59, p. 260; 1928) stated that the distinctive generic characters are “capacious aperture, disproportionate body-whorl, position of plait, and curiously set nucleus,” and that these differentiate this form from all other New Zealand species.

The embryo is planorboid and rather curiously tilted. The general habit of the shell is at once distinctive, and there can be no confusion with other Odostomid groups. Spiral sculpture is present in the form of irregular, weak microscopic striations, but this is not necessarily of more than specific significance. Key to Species of Gumina. Shell large, body-whorl capacious; microscopic spiral striae indistinct; whorls lightly convex; spire slightly staged. dolichostoma Shell small, more slender; body-whorl not so capacious; microscopic spiral striae well developed; whorls more strongly convex; spire not staged, but suture well impressed. minor Gumina dolichostoma (Suter). (Fig. 10.) 1908. Odostomia dolichostoma Suter, Trans. N.Z. Inst., vol. 40, p. 365, pl. 29, fig. 11. 1913. Odostomia dolichostoma Suter, Man. N.Z. Moll., p. 336, pl. 16, fig. 18 (Atlas). 1928. Gumina dolichostoma (Suter). Finlay, Trans. N.Z. Inst., vol. 59, p. 260. Suter's types are but immature shells, for the writer has from Takapuna, which is practically the type locality, an adult specimen of considerably greater size (see dimensions below). Height, 4·0 mm.; width, 2·0 mm. (holotype). Corresponding dimensions of a specimen from Takapuna Beach: 6·6 mm.; 3·3 mm. Localities: Cheltenham Beach, Auckland (type); Takapuna Beach, Auckland; Spit Beach, Otago Harbour; Chatham Islands. Type in Wanganui Museum. Gumina minor Laws. 1940. Gumina minor Laws, Trans. Roy. Soc. N.Z., vol. 70, p. 53. pl. 6, fig. 16. Localities: Mangapani, near Waitotara (Pliocene), type; Nukumaru (Nukumaruan); Awanui Bay, in 12 fathoms; Doubtless Bay, in 12 fathoms. Type in writer's collection. Genus Sinuatodostomia Nomura. 1937. Nomura, Saito Ho-on Kai Mus. Res. Bull., no. 13. p. 23, pl. 6, figs. 24a. 24b. Type (o.d.): Odostomia sinuosa Nomura. Recent, Japan. The definition of this genus (instituted by Nomura as a subgenus of Odostomia) is as follows: “Odostomia having a distinct subsutural sinus at aperture. The surface marked by many very distinct flexuose growth lines, crossed by numerous microscopic spiral striae.” Sinuatodostomia neozelanica n.sp. (Fig. 8.) Shell very small, outlines straight, sutures strongly cut in, whorls lightly convex to flat, height of body-whorl less than half that of shell. Protoconch heterostrophic, large, heavy, its lateral nucleus coiled in a high helicoid spiral and overhanging first adult volution. Surface worn so that minute sculpture, if originally present, has been obliterated. Periphery angulated. Aperture broadly ovate; columella thin, a little arcuate, with a light fold above. Umbilical perforation present. The most interesting feature of this shell is the very distinct subsutural sinus on outer lip. The entire outer lip is well preserved

so that this character shows up extremely well. The growth-lines on the body-whorl also show the presence of a distinct sinus at earlier stages of growth; while those on the penultimate whorl show that the sinus, though present at that stage, was not as deep as that of the adult. Height, 2·25 mm.; width, 1·15 mm. Locality: Kaawa Creek beds (Waitotaran). Type (unique) in writer's collection. This interesting shell turned up unexpectedly in sievings obtained at Kaawa Creek in 1936.