The Molluscan Faunule at Pakaurangi Point, Kaipara. No. 2.
[Read before the Auckland Institute, October 9, 1940; received by the Editor, February 4, 1941; issued separately, September, 1941.]
This paper, which is purely systematic, includes description of new species and genera, many of which have been collected at Pakaurangi Point since paper No. 1 of this series (Trans. Roy. Soc. N.Z., vol. 68, p. 466, 1939) was published. The present paper does not exhaust the record of new forms found at Pakaurangi. In a paper now being prepared further new species will be described and the faunule discussed.
The writer gratefully acknowledges his indebtedness to Professor Bartrum. who has been almost entirely responsible for the photography. Many of the species illustrated are very small, some of them minute. Figures 26 and 47 are enlargements made by Professor Bartrum from his original photographs of very minute shells.
Unless otherwise stated, the types are located in the writer's collection.
Nucula (Linucula) waiaotea n.sp. (Fig. 2).
Shell small, its outline closely similar to that of N. tutamoensis. Beak strong, at about posterior fourth. Sculpture scarcely evident under hand-lens; microscope shows weak concentric corrugations here and there and fine radial lines apparently in the substance of the shell; lunule with diverging sculpture well shown under microscope, this scarcely discernible on escutcheon. Valve margins crenulated. Hinge largely covered with matrix that cannot be removed; teeth 7 or 8 in number in front of beak, spaced.
Height, 2·2 mm.; length, 2·7 mm.; inflation, 1·5 mm.
Differs from tutamoensis in the less pouting posterior slope, much weaker radial sculpture and presence of weak concentric folds. The divergent ribbing on lunule seems to be better defined. Three individuals were collected.
Ledella pakaurangiensis n.sp. (Fig. 12).
Similar to clifdenensis, with which it occurs in the same bed, but higher in relation to length than clifdenensis, the shell being drawn down more ventrally. The rostrum is not so pointed, nor is it directed so much downwards distally; the postero-dorsal slope does not descend as rapidly as that of clifdenensis; the beak is fuller and is directed more inwards. Posterior area along dorsal margin narrower than that of clifdenensis. Hinge and teeth heavier, the hinge-plate not narrowing as much below beak.
Height, 2·0 mm.; length, 3·0 mm.; inflation, 1·2 mm.
Three specimens collected.
Hochstetteria dupliradiata n.sp. (Fig. 6).
This is a very distinct species on account of the unusual disposition of its radial threads. The major radials are closely paired threads separated by very wide interspaces in which are set finer radial threads. A secondary (unpaired) rib runs down the middle of each primary interspace; in the interspaces between these secondary riblets several tertiary radials develop towards ventral margin. Close-set concentric threads are developed over the entire surface of valve; these are of much the same strength as the radial elements of sculpture. The anterior slope just below prodissoconch, which is terminal, is excavated. Ventral margin crenate. Taxodont teeth developed both in front of and behind prodissoconch.
Height, 1·75 mm.; length, 1·6 mm. (estimated).
A single valve collected. The posterior end is broken off, but the sculpture is so unlike that of other local species that a name has been assigned to the species.
Hochstetteria zearanea n.sp. (Figs. 1, 3).
Shell very small, nearest in shape and sculpture to H. awamoana (described in Appendix), but differing in smaller size, terminal prodissoconch, lack of crenulations on margin, and better differentiated teeth. The sculpture consists of fine, threadlike radials and very indistinct concentric threads, much as in awamoana. There is a small pad of taxodont teeth in front of the prodissoconch and a long one behind, below which extends a long narrow ridge-like tooth, not present in the Awamoan form, though the taxodont teeth are similar in both species.
Height, 1·6 mm.; length, 1·4 mm.
The type material consists of odd right and left valves. Twenty-two valves collected. H. tela, though similar in sculpture, is narrower in relation to height than either awamoana or zearanea. This is the form listed by the writer (Trans. Roy. Soc. N.Z., vol. 68, p. 466, 1939) as “Hochstetteria n.sp.”
Pitar (Hyphantosoma) sculpturatus (Marshall).
1918. Macrocallista soulpturata Marshall, Trans. N.Z. Inst., vol. 50, p. 272, pl. 21, figs. 6, a.
1927. Pitar (Hyphantosoma) sculpturatus (Marshall); Marwick, Trans. N.Z. Inst., vol. 57, p. 594, figs. 74–70.
1939. Pitar (Hyphantosoma) sculpturatus (Marshall); Marwick, Trans. Roy. Soc. N.Z., vol. 68, p. 79, pl. 10, figs. 8, 11.
Up to the present no left valves of this species have been available for description, but recently several have been obtained from the beds at Pakaurangi, the type locality. The left hinge (individual 23 mm. long) proves to be very similar indeed to that of carbaseus, the genotype. The posterior cardinal tooth is long and is separated from the nymph by a deep depression of moderate width, though not, perhaps, as wide as that of carbaseus, judging by Woodring's figure (Miocene Mollusks from Bowden, Jamaica. Pelecypods and Scaphopods. Carnegie Inst. of Washington, Publication No. 366, pl. 20, fig. 18, 1925). The left valve of an individual 12 mm. long shows the posterior cardinal relatively shorter and closely situated against nymph, from which it is separated by an almost linear, though deep,
distinct groove; there seems to be no connection between nymph and cardinal comparable with that of Fossacallista. As with carbaseus, so apparently with sculpturatus, the left posterior cardinal diverges more from nymph with age. The left anterior lateral of both sculpturatus and carbaseus is oblique to lunular margin, that of Fossacallista parallel with it; further, the posterior end of this tooth in both these species extends as a very low spur along edge of hinge towards ventral end of anterior cardinal, whereas in Fossacallista the spur extends dorsally, and the anterior lateral, if produced posteriorly, would intersect the anterior cardinal at or near its dorsal extremity. In Fossacallista from Clifden, however, the main part of the lateral intersects the cardinal at about its middle, but the spur descending from its posterior end bends around dorsally towards the upper end of the cardinal. Hyphantosoma shows no trace whatsoever of an extension towards the upper limit of the anterior cardinal, but instead an uninterrupted broad, triangular pit.
In spite of the similarity between Fossacallista and Hyphantosoma in hinge characters it seems on the evidence that sculpturatus must be regarded as a true Hyphantosoma. As Marwick has pointed out (Trans. Roy. Soc. N.Z., vol. 68, p. 80, 1939) New Zealand has in Austrovenus and Tuangia other Venerid faunal contacts with the southern part of North America. The style of the present shell and its unusual sculpture, together with the features of the hinge, produce a combination that is too close to that of carbaseus to satisfy belief that it is a product simply of parallel development. *
Notocorbula innerans n.sp. (Figs. 4, 5).
Shell small, resembling pumila in convexity and sculpture. The concentric ribs of right valve are finer and narrower than those of illecta n.sp., in fact very similar to those on topotypes of pumila. Pumila has postero-dorsal margin rising more steeply, the beak more prominent, the posterior end not truncated, and the shell larger. The sculpture of left valve of innerans resembles that of pumila, consisting of thin, distinct, evenly spaced concentric threads. Several specimens from this bed appear to be hybrids. In these the upper half of each valve shows the characters of innerans, then there is a
[Footnote] * Since the above observations were made the left valve of sculpturatus has been inspected by Dr. Marwick, who has written as follows: “As regards the resemblance of the hinge, it agrees closely with that of the genotype. The thick posterior cardinal of ther right valve and the somewhat narrower space behind it led me to suppose that the left valve might show further differences from the genotype. But this is not so. The left anterior and median cardinal unit has the same set, the anterior cardinal sloping slightly backwards and downwards. The anterior denticle, like that of the genotype, is distant from the cardinal and placed near and parallel to the ventral margin of the hinge plate. It thus differs from the Notocallista and Fossacallista groups in which the lateral diverges from the margin and is buttressed towards the umbo. The left posterior lateral is straighter than in the genotype, but the difference is not great. It is separated from the nymph throughout. The ventral margin of the hinge-plate has the same sinuosity as has carbaseus, also the very large lunule of sculpturatus agrees with that of the genotype.”
sudden discontinuity involving change to the sculpture of illecta. This is particularly clearly shown on the left valve of such individuals.
Height, 3·0 mm.; length, 3·35 mm.; inflation, 2·5 mm.
Localities: Pakaurangi Point (type); Clifden, Southland, bands 4, 6A, 6B, 6C, 7, 8.
Notocorbula illecta n.sp. (Figs. 7, 11).
Shell of moderate size for the genus, at first sight very like N. humerosa in appearance. Readily distinguished, however, in having the beak much narrower, rising more above dorsal margin; valve drawn out more posteriorly, so that postero-dorsal slope is not so rapid; the interstices between concentric ribs relatively wider, the ribs appearing more sharply elevated, thinner and more distant; the surface of valve between the two posteriorly trending carinae is concave, that of humerosa flat. Left valves have finer though less regular concentric threads, are consistently marked by strong, distant growth-stages that step the surface, and have the hinge broader and heavier. The posterior end is truncated more sharply than that of humerosa.
Height, 8·5 mm.; length, 10·1 mm.; inflation (right valve), 5·0 mm.
Localities: Pakaurangi Point (type); Clifden, Southland, bands 4, 6B, 6C.
Many specimens of illecta have been collected. The above comparison with humerosa has been made using topotypes of that species. This is the “Corbula humerosa” of earlier lists of the Pakaurangi Point faunule.
Schismope kaiparaensis n.sp. (Fig. 9).
Shell very small, spire stepped; periphery bearing a pronounced double keel whose sharp lamellar ridges border the slit fasciole. Fasciole crossed by sharply elevated arched ridges, concave towards aperture. Whorl flattish above keels and ornamented on this portion with four sub-equidistant fine spiral threads, which are crossed by spaced axial threadlets, recurved and dying out downwards towards keels. Below fasciolar keels whorl is concave and here carries several thin spiral threads and numerous weak hairlike axials, antecurrent above. Along the anterior border of concave zone there extends a sharp, strongly raised spiral keel, emerging from suture not far behind posterior angle of aperture. On the base there are four weaker though quite distinct spiral threads, and a fifth entering the moderately wide umbilical hollow. In addition to spirals the base carries numerous fine distant axial threadlets, weaker than the spirals, which they surmount. These axials converge on to and enter the depression of the umbilicus. The lowest spiral on the base forms a heavy cord bordering the depression.
Height, 1·0 mm.; width, 1·3 mm.
Nearest to S. ngatutura, which has more numerous concentric threads above fasciole; stronger ones in concave zone below fasciole, the axials here being almost obsolete in kaiparaensis. In both species there are three spiral cords (excluding that at edge of umbilicus) below the heavy subfasciolar keel; in ngatutura the middle one of these is the strongest, whilst kaiparaensis has them becoming progressively weaker towards umbilicus.
Zeminolia ordo n.sp. (Fig. 46).
Shell small, spire staged, its height very little more than that of body-whorl. Embryo large, bulbous, smooth. First 1½ post-embryonic volutions evenly convex and carrying 5 or 6 spiral cords. Later whorls develop a strong keel close below suture, the zone between suture and keel being practically horizontal and marked by very fine microscopic spiral striae. The keel carries weak nodules spaced about own diameter apart and axially produced downwards as weakening folds, retrocurrent to suture. Below keel on penultimate whorl there are about 6 weak narrow spirals separated by wide interspaces. Periphery sharply angulated. Base lightly convex; umbilicus wide, its diameter one-third that of base. Base largely decorticated, but there is one place where trace of the moniliform cord around umbilicus can be detected.
Height, 2·2 mm.; width, 3·5 mm.
This species is closer to lenis Marwick than to any other described species, but the dimensions are notably different (lenis more elevated), and also lenis has fewer whorls. They appear to be close to one another in sculpture.
Z. ordo has certain features in common with Z. fossa Laws, a fossil from the greensands at Wharekuri, Waitaka Valley. At the time of description of fossa the writer stated that the sculpture of the fossil could reasonably be expected to be bridged by connecting links with that of the Recent genotype. The new species provides one of these links. Ordo resembles fossa in general form and in the nature of its posterior keel with development of axials. In ordo the deep channelling of suture has been lost and the doubly keeled periphery of fossa has given place to one that is sharply angulated, thus carrying the general facies of the species a step nearer to that of Recent forms. Z. carinata Laws (Awamoan), a species described subsequent to fossa, carries the evolution of Zeminolia a step further, for it grades towards plicatula, while ordo is intermediate between it and fossa.
Conominolia aflexura n.sp. (Fig. 22).
Shell small, elevated, conic, whorls (5 in number) regularly and lightly convex, sutures distinct. Protoconch small, smooth, convex; early post-nuclear volutions with faint spirals evenly spaced on whorl; penultimate whorl with 4 spiral threads, the posterior one very weak, the others distinct, equidistant and of equal strength. Body-whorl with periphery angled; above angulation there are 4 coarse, spaced spirals, and a much weaker one nearer posterior suture; base convex and ornamented with numerous fine, close spiral threads. A coarse, nodulated spiral rib borders edge of umbilical hollow, within which there are several penetrating spirals of rather coarse texture. Inner lip scarcely notched where met by circum-umbilical rib, and therefore not so sinuous as those of vixincisa and woodsi.
Height, 3·4 mm.; width (greatest), 3·15 mm.
Separable at a glance from vixincisa, which has flat whorls. Woodsi has spirals very much more strongly developed. Sulcatina is a much larger species, though somewhat similar in general form, and has the spirals more numerous and stronger above periphery
but not so numerous on the base. This is the “Conominolia n.sp.” of the writer's former list (Trans. Roy. Soc. N.Z., vol. 68, p. 467, 1939.)
In instituting Conominolia and Antisolarium Finlay (Trans. N.Z. Inst., vol. 57, p. 360, 1927) stated that Antisolarium seems to be a late development of Conominolia. Although several species of Conominolia have since been recorded, none are known in post-Tertiary faunas. Antisolarium, however, at the time of its inception known only as a Pliocene and Recent genus, has been found to date back much earlier than supposed, for the record of A. castigatum (Hutchinsonian and Awamoan of Gisborne district) and A. tricarinatum (Hutchinsonian at Pakaurangi Point) indicates that after all this genus is not to be regarded as a late derivative of Conominolia. Tricarinatum shows considerable divergence from Pliocene and Recent species of the genus, but, as pointed out at the time of description (Trans. Roy. Soc. N.Z., vol. 68, p. 478, 1939), it is to be expected that the discovery of ancestral species will help to connect tricarinatum with Pliocene and Recent forms. Notwithstanding its divergence from the Recent A. egenum, the genotype, this ancestral species from Pakaurangi Point possesses the essential characters of the genus as defined by its author.
It is interesting to note that the four genera proposed by Finlay to cover the Neozelanie Minolioids are represented in the beds at Pakaurangi Point—Antisolarium, Conominolia and Zeminolia by one species each, and Zetela by several distinct forms.
Lodderia supralevis n.sp. (Fig. 18).
This is the shell identified in the writer's former list (Trans. Roy. Soc. N.Z., vol. 68, p. 467, 1939) as Crosseola tenuisculpta Laws, a Waitotaran fossil from Kaawa Creek. Three good specimens now to hand make it necessary to distinguish the Pakaurangi shells as a separate species. They differ from tenuisculpta in taller habit and obsolescence of cancellate sculpture over the posterior half of the body-whorl. The penultimate whorl is heavily cancellate and similar sculpture is present below periphery of body. The aperture is circular with no canaliculation in front, and a broad rather smooth rib encircles left side of the narrow umbilical chink. The body carries seven heavy spirals.
Height, 1·0 mm.; width, 1·0 mm.
Conjectura congrua n.sp. (Fig. 48).
Akin to C. proava, a fossil from the Ihungia Series (Hutchinsonian) of Gisborne district. The spire is very low, though rather more elevated than that of proava. Otherwise the general outline and build is very similar in both species. The number and arrangement of umbilical cords offers ready means of distinguishing them, however. The present species has 4 cords, which are thin and sharply elevated. Outside the fourth, which forms a distinct ridge around edge of umbilical hollow, the base carries a few weak spiral threads, diminishing in strength towards periphery.
Height, 1·3 mm.; width, 1·5 mm. These are the dimensions of a paratype. The holotype is rather smaller.
Two specimens collected.
Argalista aequor n.sp. (Figs. 27, 29).
Distinguished from all other Neozelanic Argalista by the perfectly plane posterior surface. Otherwise the shell resembles A. umbilicata very closely indeed, particularly in features of aperture and development of umbilicus. The upper flat surface lacks sculpture, but the base is spirally lirate, the spiral around umbilicus being the coarsest, those further away becoming progressively finer; towards periphery they are fine and crowded together. The last half of base is ornamented in addition with about 15 broad, low, slightly sinuous radials, separated by very narrow almost linear grooves. Spiral, threads are also present within umbilicus. The apertural features (shape, pillar with its pad) are almost a replica of those of umbilicata, to which the species is obviously directly ancestral.
Height, 1·0 mm.; diameter (greatest), 1·8 mm.
Lodderena anceps n.sp, (Fig 43).
Shell very small, spire low, distinctly stepped, its height about ¼ that of body-whorl. Whorls of spire angulated at about 90 degrees halfway between sutures, thus causing the spire to appear as a series of terraces. The angulation carries a spiral cord. Embryo smooth, rounded. The flat upper surface of body-whorl has thin, spaced threads (mostly worn away) crossing it, and these are slightly retracted from suture. The body carries two strong keels, one at edge of flat upper surface, the other at about periphery. Between these the surface descends vertically and is unsculptured save for a weak fold encircling it at about its middle; here and there on this zone, however, there is indication of weak spiral threads. The base has 4 low, weak, concentric folds, the outer two of which are thin raised threads, the next inwards being a very broad low swelling, the innermost constituting the keel around depression of umbilicus. The umbilicus contains a good deal of matrix that cannot be cleared away without risk of damaging the shell, but it is deep and is seen to descend steeply from edge of base; its diameter is about one-third that of base. Base in addition has very thin radial threadlets. Aperture quadrate, outer lip broken back.
Height, 1·25 mm.; width (greatest), 1·65 mm.
This species is not confidently referred to Lodderena, but is located here on account of its superficial resemblance to L. nana Powell. Otherwise it does not fit into any genus known to the writer.
Estea asymmetrica n.sp. (Fig. 28).
Shell very small, heavily axially costate, spirals absent. Axials strongly pinched up, separated by wide grooves. Submargining of suture is indicated by nodulation of axials at their posterior extremities; there is also faint nodulation at anterior ends of axials; axials straight, almost vertical. Outline of left side of shell much more convex than that of right side. The axials die out early on base.
Height, 2·0 mm.; width, 1·0 mm.
E. impressa (Hutton) has axials finer, more numerous and closer together. E. rugosa (Hutton) has spirals developed. E. verticostata Powell and Bartrum has whorls lightly convex (not flat as in the n.sp.), the sutures better defined and no submargin to suture. E. semiplicata Powell is bigger and of different build.
Scalaronoba pristina n.sp. (Fig. 26).
Shell minute, height of spire about 1½ times that of aperture. Protoconch sculptured with several coarse spiral threads. Adult whorls with numerous prominent, vertical, narrow axial ribs; interspaces deep, rather wider than the ribs. Ribs present on base, converging into narrow umbilical hollow. Peristome continuous, roundly oval, its longer axis approximately vertical.
Height, 0·7 mm.; width, 0·5 mm.
Pristina has the body-whorl wider in relation to height of shell than that of costata, the genotype (Recent), and hitherto the only recorded species of the genus. Costata has recently been found in sievings from the Pliocene beds at Kaawa Creek.
Ihungia aequalis n.sp. (Fig. 25).
Shell very small, height of spire about 1½ times that of aperture. Protoconch typical of genus. Build and sculpture of adult whorls close to that of luteophila, the genotype. This species possesses characters intermediate between those of luteophila and amberleya. Unlike the former its axials persist across entire whorl on the body; there is a spiral cord connecting tubercles on periphery of all whorls. The third spiral on the base is better developed, while a fourth very weak one can be observed in favourable light. The suture is margined above by a distinct but narrow smooth cord, not present in any of the Gisborne species. There is no spiral above periphery, as in amberleya; like amberleya, aequalis has a cord connecting the tubercles, but this is not present in luteophila.
Height, 2·25 mm.; width, 1·3 mm.
Two specimens collected. True Merelina is present also in the beds at Pakaurangi, so that Ihungia can hardly be regarded as an ancestral form of Merelina.
Notosetia epulata n.sp. (Fig. 40).
Shell very small, of stumpy habit, height of spire a little greater than that of aperture. Whorls strongly convex, sutures very well marked. Body-whorl considerably swollen. Aperture rounded, peristome continuous, outer lip with a broad varix externally. Umbilical chink well marked. Ornamentation absent.
Height, 1·3 mm.; width, 1·1 mm.
Six specimens collected. Close to N. prisca Finlay, a fossil from Pourakino, Southland, but distinct in its squat shape and very full body-whorl. Also the umbilical perforation is better differentiated.
Notosetia bucina n.sp. (Fig. 31).
Shell very small, solid, body large, height of spire equal to that of aperture. Embryo small, exsert, smooth, ending in a varix. Whorls convex, sutures distinct. Unsculptured, growth-lines antecurrent to suture above; outer lip oblique in conformity with trend of growth-lines. Aperture roundly oval, angled behind, lips thick. Columella fairly solid, arcuate, set vertically. Umbilical chink present near insertion of columella.
Height, 1·5 mm.; width, 1·1 mm.
Two specimens collected. Not particularly close to any described form.
Scrobs praeco n.sp. (Fig. 32).
Shell minute, whorls convex, sutures distinct; height of spire about one-third that of shell, and equal to that of aperture. Protoconch with its nucleus small, smooth, depressed. Adult whorls ornamented with fine microscopic spiral threads. Suture descending whorl towards aperture, thus being well below periphery. Aperture roundly oval; outer and basal lips broadly convex; inner lip separated from body by a deep narrow channel, except at its posterior where it meets posterior of outer lip to connect with parietal wall.
Height, 1·35 mm.; width, 0·85 mm.
Resembles S. crassiconus Powell somewhat in form, but crassiconus has the aperture spreading more laterally. It is abundantly distinct from other Neozelanic species. This record, a new one for the locality, is the first record of Neozelanic Scrobs in rocks of earlier age than the Pliocene.
Dardanula subexcavata n.sp. (Fig. 39).
This species is obviously closely allied to D. rivertonensis Finlay, a fossil from Pourakino, Southland. It differs in being wider across the body, and in having the whorls wider in relation to height than are those of the South Island species. Also the apical whorls are more convex. The base adjacent to posterior part of inner lip and just below the periphery is excavated like that of rivertonensis, perhaps rather more so. The two species agree in all other shell characters.
Height, 2·2 mm.; width, 1·35 mm.
Dardanula sedicula n.sp. (Fig 10).
Shell minute, solidly built, outlines straight; whorls lightly convex, sutures moderately distinct. Height of spire 1½ times that of aperture. Aperture roundly oval, rim thick; peristome continuous, but callus of inner lip thin on parietal wall. There is a small but very distinct umbilical perforation present.
Height, 1·0 mm.; width, 0·7 mm.
Three specimens collected. Roseocincta (Suter) and minutula Powell are also small species, from which sedicula may be distinguished at a glance by the umbilical perforation.
Rissoina heterolira n.sp. (Fig. 35).
Shell of moderate size, axially costate and spirally lirate; height of spire about twice that of aperture, its outlines lightly convex. Upper whorls of spire flattish; the last two whorls bulging anteriorly. Suture moderately distinct; last whorl clasping. Aperture angled behind, strongly notched below columella, spreading laterally below; basal lip long and lightly convex. Axials of upper half of spire sharp, pinched up, distant; about 16 axials per whorl; on penultimate whorl axial sculpture changes with little transition into very numerous thin, little elevated and closely spaced ribs, which persist on to body-whorl. Interspaces of the coarsely costate whorls carry spiral lirae densely packed together; on the body-whorl the posterior few spirals are coarse threads; over rest of surface above periphery fine dense spiral lirae are developed; from periphery down on to base coarse spiral threads again appear. The axial ribs are straight and vertical.
Height, 5·1 mm.; width, 2·0 mm.
This is a very delightfully sculptured shell, not unlike R. achatina Odhner in many respects, though the form is different. It is remarkably like R. ame Woodring, from Jamaica, and possibly should be located in Zebinella Morch, which Woodring uses as a subgenus of Rissoina.
Caecum pertenuis n.sp. (Fig. 13).
Shell very small, narrow, curved, not tapering. Septum lightly convex, not pouting so much as that of digitulum Hedley. Aperture circular, its rim considerably swollen, much more so than that of digitulum. Growth-striae scarcely visible.
Length, 1·7 mm.; width, 0·3 mm.
Pareora pinguis n.sp. (Fig. 33).
This is the previous record of P. striolata from these beds. A larger series and the acquisition of better specimens shows that there are constant differences from striolata. The Pakaurangi shells are all notably broader in relation to height. The protoconch differs from that of striolata also. Though it consists of the same number of volutions it has the tip sharper, is more prominently elevated, and not so wide spreading across the last volution; striolata has the embryonic whorls increasing regularly, the increase of post-nuclear whorls being uniform with that of embryonic ones. In pinguis the last embryonic turn is constricted, so that the previous volution overhangs it and the embryo has a different aspect, that of striolata being regularly conic. As regards sculpture it is difficult to make comparisons. In both species the first post-nuclear whorl develops two strong spirals anteriorly and a very weak one above. Later whorls show very considerable variation in strength of spirals amongst different individuals, some being nearly smooth, some with moderately distinct spirals, and others with pronounced cords. This observation applies to both species. In convexity of whorl and development of sutures pinguis agrees with striolata, therein differing from incincta Marwick.
Height, 3·1 mm.; width; 1·5 mm.
Localities: Pakaurangi Point (type); Clifden, Southland, band 6C.
The Pareora in band 8 at Clifden is intermediate between pinguis and striolata. It has the build and proportions of striolata, but the embryo of pinguis. Shells from Mahoenui beds, Awakino Gorge, are practically identical with the Pakaurangi species.
Mathilda kaiparaensis n.sp. (Fig. 36).
Shell small, height of spire about 1½ times that of body, outlines straight, whorls strongly and heavily keeled at anterior third, the keel nodulous. Protoconch heterostrophous, large, coiled in a low helicoid spiral, slightly tilted, the nucleus small and about one-half immersed. There are 2 to 3 spiral cords above keel and another below, close to suture, all surmounting the axials. Axials numerous, not as strong as spirals, about 18 on penultimate whorl, their intersection with spirals nodulous. Base flat, two spiral threads around its periphery, within that radiating growth-striae; a thread arising at base of columella sweeps around to end at insertion of columella.
Aperture quadrangular; columella straight, vertical, basal lip wide. Body-whorl bulging at periphery.
Height, 4·0 mm.; width, 2·0 mm.
This is the “Mathilda n.sp” of the writer's former list.
Trivia aequiflora n.sp. (Figs. 44, 49).
Shell quite small, ovate, inflated. Dorsum smooth, ribs reaching a little over halfway from lips. Ribs very thin, sharp, spaced widely, 15 in number from outer lip, 11 in number reaching inner lip; between second and third from anterior on inner lip there is a rib that fails to reach the lip; similarly a rib situated between fourth and fifth from posterior on inner lip also fails to enter. Only tip of spire visible as a low broad swelling defined by a circular depression separating it from surface of body.
Height, 3 7 mm.; diameters: left to right, 3·0 mm.; front to back, 2·5 mm.
Nearly related to T. flora Marwick, a fossil from Chatham Islands. Flora has the ribs more numerous and not ascending so far; and the dorsum conoid, that of aequiflora being evenly convex throughout.
Finlay (Trans. N.Z. Inst., vol. 57, p. 396, 1927) has advocated reference of T. pinguior Marwick, T. zelandica Kirk, and shells like them to Trivia for the present.
Eratopsis erro n.sp. (Fig. 24).
Shell small, elongate, slowly contracting towards anterior. Apex decollated. Dorsum smooth above, but marked by irregular elongate granules below. Aperture broadening in front. Outer lip heavily thickened, finely granulated externally, bearing about 12 elevated denticles along internal edge. Fossula very broad, smooth. Base of columella with two pronounced radially disposed ridges of sub-equal strength. Above these inner lip is excavated, reminding one somewhat of Willungia. Denticles along entire length of inner lip, sharp and distinct in front, weakening towards posterior.
Height (estimated), 5·9 mm.; width, 3·3 mm.
Hespererato zevitellina n.sp. (Fig. 37).
Simulates Marginella in form and has the apertural shape of Proterato tenuilabrum (Laws); but there is only a single terminal ridge at anterior outlet, which it borders, not several parallel ones as in Proterato. Behind terminal ridge there are three or four denticles spaced over anterior third of columella, obsolete behind that. In order to determine whether these were denticles or the ends of weak pillar-plaits, it was necessary to pierce the dorsal surface of the body. The fossula is scarcely defined.
Height, 5·1 mm.; width, 3·1 mm.
The reference to Hespererato is perhaps rather doubtful, but the fossula is definitely obsolete, and this precludes locating the shell in Archierato.
Genus Kaiparathina nov.
Type: Kaiparathina praecellens n.sp.
Shell very small, regularly conic; aperture circular, columella heavy, flattened and expanded below, bordered on left by a fasciolar ridge; whorls strongly angulated; sinus broad and shallow, situated on base, rather nearer periphery than columella. Whole surface smooth except for weak growth-lines which are slightly curved and strongly antecurrent to posterior suture. Sutures distinct, whorls abutting. Embryo few-whorled, projecting, bulbous.
Ianthina has the sinus on periphery, whilst Heligmope has it located close in against columella on the last spiral.
Kaiparathina praecellens n.sp. (Fig. 38).
Essential features given in generic diagnosis above. The angulation at periphery bears a light but distinct keel. Base lightly convex, in some specimens showing about five dark spiral bands that seem to be in the substance of the shell and may represent original colour-markings. Inner lip with a very light parietal callus; columella heavy, arcuate, set vertically, flattened, expanded below. Spire of about same height as aperture.
Height, 2·5 mm.; width, 2·2 mm. Corresponding dimensions of largest of the thirty odd paratypes; 3·2, 3·0.
Architectonica spinogula n.sp. (Figs. 41, 42).
Not unlike A. aucklandica from the same beds, but has the base more convex; the peripheral keel not so sharp, and smooth instead of beaded; the umbilicus a little narrower; the summit more convex. Aucklandica has spirals on upper surface bearing small but distinctly elevated granules; on the new species the granules are much less in evidence, being flattened and closely packed together. The base has one distinct spiral near periphery, then 3 or 4 weaker ones inside that; the remainder of base without spiral sculpture. Strong irregular axial folds develop approximately along inner boundary of spirals and project as prominent, heavy teeth overhanging edge of umbilical hollow, about 16 of these on last volution. Aucklandica has the base smooth except for microscopic spiral striae.
Height, 4·0 mm.; diameter (greatest), 6·5 mm.
Five specimens collected. There is an allied though distinct form in the beds at Clifden, Southland.
The following Pyramidellids have been found in the Pakaurangi beds.
Turbonilla komitica Laws.
Turbonilla duplicaria Marwick.
Turbonilla cf. bexleyana Laws.
Turbonilla cf. natales Laws.
Turbonilla cf. awamoana Laws.
? Turbonilla n.sp.
Chemnitzia granti Laws.
Chemnitzia brevisutura Laws.
Pyrgolampros pakaurangiensis Laws
Mormula locuples Laws.
Mormula tutamoensis Laws.
Finlayola angulifera Laws.
? Terelimella pravitas n.sp.
Eulimella waihoraensis (Marwick).
Eulimella parlimbata Laws.
Eulimella imitator Laws.
Eulimella komitica Laws.
Pyrgulina n.sp. A.
Pyrgulina n.sp. B.
N.gen. n.sp. aff. Pyrgulina.
Turbonilla cf. natales Laws.
One juvenile shell having the characteristic posterior nodulation of axials, but the sculpture rather finer. T. natales is a species occurring at Clifden.
? Turbonilla n.sp.
A puzzling shell, having the characters of Turbonilla Group B (i.e. Turbonillas with paucispiral, planispiral embryos) except that the shell is minute and of stumpy habit. It resembles certain Pyrgulinid genera, but there is no plait. A single specimen collected.
Chemnitzia granti Laws.
Three shells. They match well the Clifden ones, except that the axials are slightly more oblique.
Eulimella komitica Laws.
Although not a few specimens were available for the original description, it turns out that none of them was full grown. A larger specimen, 4·1 mm. high, is now to hand.
There is a single specimen. The sharpened apex is reminiscent of that of E. levilirata. The embryo is coiled in a moderate helicoid spiral, its lateral nucleus tangent to suture of first adult volution. Whorls flat, sutures not very distinct. Columella arcuate, set vertically. Outer lip broken.
? Terelimella pravitas n.sp. (Fig. 47).
Shell minute, needle-like, unsculptured, height of body equal to half that of shell, the height of aperture about half that of body-whorl. Whorls higher than wide, lightly convex, strongly shouldered above; suture below periphery, well cut in. Protoconch exsert, coiled like that of Terelimella. Body-whorl full over base, angulated very low down; aperture peculiar, somewhat triangular, narrow behind, basal lip wide and rather straight, its junction with the vertically descending and straight outer lip angulated. Inner lip long and straight, lightly and narrowly callused. Growth-lines curved, convex towards outer lip.
Height, 1·15 mm.; width, 0·3 mm.
Two specimens collected. Not a typical Terelimella. It agrees with Terelimella in features of embryo and in having sutures low down; but the peculiarly shaped body and aperture are distinctive.
The unusual number of species of Eulimidae, all found in the same bed at Pakaurangi Point, is striking. The conditions of habitat during deposition of this particular stratum seem to have favoured the existence of many small molluscs. Though larger forms are present, yet the variety of small species of many families is an outstanding feature. The following Eulimidae have been collected:—
Balcis badenia Laws.
Balcis kaiparaensis Laws.
Balcis lentocontracta n.sp.
Balcis cf. christyi (Marwick).
Balcis (Vitreolina) waikomitica Laws.
Balcis (Vitreolina) waiaotea n.sp.
Balcis (Vitreolina) cf. patutuensis (Marwick).
Eulima aoteaensis Marsh. & Murd.
Balcis lentocontracta n.sp. (Fig. 34).
Shell small, outlines of spire straight, apex sharp; whorls practically flat; suture indistinct. Body-whorl long, its height a little over one-half that of shell; flattish above, broadly convex over periphery, drawn out notably and contracting slowly below. Aperture long, narrowly ovate, angled behind and narrowly rounded in front; columella arcuate, set vertically; parietal wall callused; outer lip thin, slowly retracted to suture, broadly convex below (lateral view).
Height, 5·0 mm.; width, 1·5 mm.
Three specimens. Distinct on account of long body with produced anterior.
Balcis (Vitreolina) waiaotea n.sp. (Fig. 8).
Shell very small, slender, axis curved; whorls flat, sutures very indistinct. Embryo narrowly rounded over summit. Height of body-whorl greater than one-third that of shell; base long, very lightly convex; periphery high up and marked by a very faint angulation. Aperture narrowly ovate, narrowly rounded in front, sharply angled behind; columella slightly arcuate; parietal wall with distinct callus, but not extending much outside aperture; outer lip thin, retracted to suture, convex below.
Height, 2·6 mm.; width, 0·7 mm.
Twelve specimens collected.
Verconella bartrumi n.sp. (Fig. 19).
This is the form discussed by Finlay (Trans. N.Z. Inst., vol. 61, p. 70, 1934) when describing V. parans, a fossil from Clifden. Finlay drew attention to the small embryo of the Pakaurangi shell, but made no mention of other divergent characters, provisionally identifying the Pakaurangi specimen he examined as V. parans. Additional shells from Pakaurangi Point show that the tiny embryo is a constant feature, but that there are several other characters by which they can be distinguished from parans. The protoconch, besides being smaller, consists of 2 as against 2½ volutions in parans; the canal is more twisted in all specimens and the fasciolar ridge much better defined and sweeping more to the left. The beak is then bent in towards axis of shell and not so straight as that of parans. The spire of parans is a little higher in relation to height of body, and its outlines tend to be very lightly concave posteriorly, those of bartrumi straight. Also the early spire-whorls of bartrumi have greater width relative to height than those of parans. Bartrumi has the spiral sculpture on shoulder finer and denser; and the species grows to a larger size. The above distinguishing characters have been drawn by comparing a number of individuals of each species.
Height, 57·0 mm.; width, 30·0 mm.
The small embryo of this species approaches somewhat that of the Australian Austrosiphos, roblini Tennison-Woods, longirostris Tate, and concinna Tate, which have been examined; but the whole facies of the New Zealand shell, apart from the protoconch, is distinctly that of our Verconellas.
Xymenella protocarinata n.sp. (Fig. 45).
Shell very small, spire stepped, its outlines straight. Axials prominent, sharply elevated, numerous (about 12 on body), spaced a little more than own width apart, not developed on base. Spirals less heavy than axials, two evenly spaced on spire-whorls; body-whorl with two prominent spirals, one at edge of shoulder, the other a little below periphery; a weak interstitial spiral between these; base with four much weaker but distinct, nodulated spirals. Aperture typical, outer lip with heavy varix, contracting rapidly below to form narrow canal, dentate within. Protoconch polygyrate, conic, symmetrical, its volutions strongly carinated at or a little below middle, nucleus minute.
Height, 3·2 mm.; width, 2·0 mm.
Localities: Pakaurangi Point (type); Clifden, Southland, band 7C.
The distinguishing feature of this species is the carinated whorling of embryo. Typically the embryonic whorls of Xymenella are convex, though some individuals (e.g. of minutissima) show tendency to sharpen the curvature around middle of whorls.
Zaclys propria n.sp. (Fig. 17).
Shell small, outlines straight, whorls well rounded, sutures very distinct. Top part of embryo decollated, lower turns with Daphnellid reticulation. Upper post-nuclear whorls with two conspicuous, sharply elevated spirals, one at middle, the other anterior to it; above and close to suture there is one very much weaker spiral thread. On later whorls the posterior thread becomes better defined, though not as strong as the other spirals. Axials are developed across whorls from suture to suture, and are thin, vertical, straight, spaced about twice own width apart, about 18 in number on later whorls. Intersections of spiral and axial sculpture sharply nodulated. Periphery of body-whorl sharply angled and keeled, the keel issuing from suture and constituting the fourth spiral on the body; base flattish, with a light thread concentric with and near to keel. Aperture quadrate, broken anteriorly.
Height (estimated), 4·2 mm.; width, 1·8 mm.
Zebittium vicinum n.sp. (Fig. 15).
Shell small, axially ribbed and spirally lirate; spire elevated, its height about 3½ times that of aperture. Protoconch decollated. Whorls convex; suture distinct. All adult whorls carry low, rounded, vertical, straight axial ribs, spaced at intervals twice their own width on upper whorls; but becoming weaker, less regular in size and spacing on later whorls, and almost obsolete towards close of body-whorl. The last two whorls bear several broad, swollen axials resembling varices. Spiral threads present on all adult whorls, and on base. These surmount axials which they nodulate. Whorls of upper spire with two strong threads and finer interstitial ones; whorls of mid-spire with three strong spirals on anterior half and three weak ones behind; on body-whorl there are eight spirals above periphery, some of them with an interstitial threadlet. The base has the outer zone carrying several very fine threads; there are three coarser spirals
adjacent to pillar. Aperture oval (outer lip broken), with a light anterior noteh.
Height, 4·2 mm.; width, 1·4 mm.
Not as slender as Z. editum Powell, but more so than Z. exile (Hutton). Z. marshalli (Cossman) has the whorls higher.
Notoseila kaiparaensis n.sp. (Fig. 23a).
Shell small, outlines straight, whorls strongly spirally keeled, sutures not distinctly marked. Each whorl has two strong spiral keels, one anterior and the other posterior. These are separated by a wide concave space along the bottom of which there is a much weaker spiral. The sutures are located between two close keels of adjacent whorls, and are defined as a linear groove. Axial sculpture consists of ill-defined threads and growth-lines. Base flattish; aperture quadrangular, lips broken. A distinct spiral thread is developed near periphery of base, which elsewhere is radially striated by growth-lines.
Height (estimated), 4·4 mm.; width, 1·3 mm.
N. terebelloides (Hutton) has three equal spiral keels. N. attenuissima (M. and M.) is more tapering and has the three spirals sub-equal in strength. There is a new species of Notoseila (described in the Appendix) in the beds at Clifden, which has the spiral keels different again, the anterior two being strong and sub-equal in prominence, the posterior one much weaker. Also the axials are much better developed.
Triphora zecollata n.sp. (Fig. 21).
Shell small, elevated, outlines straight below (upper part of spire decollated). Whorls concave medially, heavily sculptured with two spiral rows of tubercles, one row along each of the sutures. Tubercles set about half their own diameter apart and corresponding ones faintly connecting axially across sulcus. Sulcus ornamented with several usually ill-defined spiral lines. There is a spiral thread connecting tubercles of anterior series. Axials about 16 on body-whorl. Periphery very sharply angled, there being one spiral thread on angle and another close above it. Base almost flat. Aperture with lips broken back; anterior canal well twisted and apparently originally tubular.
Height (estimated), 6·0 mm.; width, 1·5 mm.
Though this species is not confidently referred to Triphora, it bears a good deal of resemblance to T. neozelanica from the same beds, and the canal seems to have been closed. Its sculpture is distinctive.
Zeacuminia fluctuosa n.sp. (Fig. 19).
Of already described species fluctuosa comes closest to pareoraensis (Suter); but the spire is rather less tapering, the early whorls not so convex and the axial sculpture ruder. The body-whorl has 18 to 20 low thin curved axials which are continued weakly over the base. On periphery each axial develops a small but distinct nodule. The anterior part of whorls is marked by a subsutural tumid border, on which the axials are developed. Below the tumid border there is a narrow, faintly sulcate zone. Whorls flat. Sutures not strongly
marked. Whole surface with fine slightly wavy spiral lirae. Fasciole and bordering ridge well developed. Protoconch worn, but apparently typical.
Height, 17·0 mm.; width, 5·0 mm.
The nodules on axials are much less prominent than those of biplex (Hutton) and planitas Laws. Three specimens collected.
Coralliophila kaiparaensis (Marshall).
1918. Phos kaiparaensis Marshall, Trans. N.Z. Inst., vol. 50, p. 265, pl. 18, figs. 4, 4a.
The writer has never been able to reconcile Marshall's figures of this species with his description; nor have his figures of Phos spiralis (loc. cit., pl. 18, figs. 5, 5a) been made to tally with the description. Examination of Marshall's types, however, explains this difficulty, for the description he has given under “Phos kaiparaensis” (p. 265) is that of Phos spiralis, and that given under “Phos spiralis” (p. 265) applies to Phos kaiparaensis. The following changes should therefore be made on p. 265: The line “Phos kaiparaensis n.sp. (Plate XVIII, figs. 4, 4a)” should read “Phos spiralis n.sp. (Plate XVIII, figs. 5, 5a)”; and the line “Phos spiralis n.sp. (Plate XVIII, figs. 5, 5a)” should read “Phos kaiparaensis n.sp. (Plate XVIII, figs. 4, 4a)”.
Marshall's statement that the type is in a good state of preservation is not accurate, for most of the surface is decorticated, the scaly character of the spirals being in evidence only near the outer lip.
Coralliophila turneri n.sp. (Fig. 16).
This shell is in the Auckland Museum (Finlay collection). Finlay identified it as Phos kaiparaensis Marshall, but notes on the back of Finlay's tablet show that he too found difficulty in reconciling description and figure. From kaiparaensis it differs notably in shape, the beak being much more drawn out, the fasciole long, narrow, and set nearly vertically and scarcely twisting round on to upper surface. The fasciolar ridge borders a narrow but deeply penetrating umbilical hollow covered over above by the reflected callus of inner lip. The spire is regularly conic, not stepped, its whorls flat (convex in kaiparaensis), angled immediately above suture, the angle bearing a strong spiral cord, the heaviest of the five on whorl. Kaiparaensis has the height of aperture a little over one-half that of shell; turneri has the height of aperture about two-thirds that of shell. The body-whorl of turneri is heaped up more posteriorly than that of kaiparaensis, the periphery bearing a strong spiral cord, forming a weak keel. Kaiparaensis has the whorl evenly rounded and no keel. Protoconch missing.
Height, 12·0 mm.; width, 6·95 mm.
Type in Auckland Museum (ex Finlay collection).
Collected by Dr. F. J. Turner. The whole facies of the shell is closely similar to that of C. miocenica (Guppy), figured by Wood-ring (Miocene Mollusks from Bowden, Jamaica, Part 2, Carnegie Institute of Washington, Publication 385, pl. 18, figs. 5, 6).
Fig. 1—Hochstetteria zearanea n.sp.; holotype, X 21.1. Fig. 2—Nucula (Linucula) waiaotea n.sp.; holotype, X 19.5. Fig. 3—Hochstetteria zearanea n.sp.; holotype, X 21.1. Fig. 4—Notocorbula innerans n.sp.; holotype, X 9.5. Fig. 5—Notocorbula innerans n.sp.; holotype, X 9.5. Fig. 6—Hochstetteria duplnadiata n.sp.; holotype, X 21.1. Fig. 7—Notocorbula illecta n.sp.; holotype, X 6.0. Fig. 8—Balcis (Vitreolina) waiaotea n.sp.; holotype, X 21.1. Fig. 9—Schismope kaiparaensis n.sp.; holotype, X 21.1. Fig. 10—Dardanula sedicula n.sp.; holotype, X 21.1. Fig. 11—Notocorbula illecta n.sp.; holotype, X 6.0. Fig. 12—Ledella pahaurangiensis n.sp.; holotype, X 17.0. Fig. 13—Caecum pertenuis n.sp.; holotype, X 21.1. Fig. 14—Hochstetteria awamoana n.sp.; holotype, X 17.3.
Fig. 15—Zebittium [ unclear: ] cinum n.sp.; holotype, X 9.5. Fig. 16—Coralliophila turneri n.sp.; holotype, X 4.4. Fig. 17—Zaclys propria n.sp.; holotype, X 9.5. Fig. 18—Lodderia supralevis n.sp.; holotype, X 21.1. Fig. 19—Zeacuminia fluctuosa n.sp.; holotype, X 3.1. Fig. 20—Verconella bartrumi n.sp.; holotype, X 1.0. Fig. 21—Triphora zecollata n.sp.; holotype, X 10.6. Fig. 22—Notoseila clifdenensis n.sp.; holotype, X 8.0. Fig. 23—Conominolia aflea [ unclear: ] n.sp.; holotype, X 9.0. Fig. 23a—Notoscila kaiparaensis n.sp.; holotype, X 7.2.
Fig. 24—Eratopsis erro n.sp.; holotype, X 9.3. Fig. 25—Thungia aequalis n.sp.; holotype, X 21.1. Fig. 26—Scalaronoba pristina n.sp.; holotype, X 74.2. Fig. 27—Argalista aequor n.sp.; holotype, X 25.0. Fig. 28—Estea asymmetrica n.sp.; holotype, X 22.0. Fig. 29—Argalista aequor n.sp.; holotype, X 23.0. Fig. 30—Acteon otamatcaensis n.sp.; holotype, X 10.0. Fig. 31—Notosetia bucina n.sp.; holotype, X 21.1. Fig. 32—Scrobs praeco n.sp.; holotype, X 21.1. Fig. 33—Pareora pinguis n.sp.; holotype, X 10.3. Fig. 34—Balcis lentocontracta n.sp.; holotype, X 9.4. Fig. 35—Rissoina heterolina n.sp.; holotype, X 9.4. Fig. 36—Mathilda kaiparaensis n.sp.; holotype, X 9.5.
Fig. 37—Hespererato ze [ unclear: ] tellina n.sp.; holotype, X 10.1. Fig. 38—Kaiparathina Praecellens n.gen. n.sp.; holotype, X 18.0. Fig. 39—Dardanula subercarata n.sp.; holotype, X 21.1. Fig. 40—Notosetia epulata n.sp.; holotype, X 21.1. Fig. 41—Architectonica spinogula n.sp.; holotype, X 5.7. Fig. 42—Architectonica spinogula n.sp.; holotype, X 5.7. Fig. 43—Lodderena anceps n.sp.; holotype, X 21.1. Fig. 44—Trivia aequiflora n.sp.; holotype, X 9.7. Fig. 45—Xymenella protocarinata n.sp.; holotype, X 17.7. Fig. 46—Zeminolia ordo n.sp.; holotype, X 9.4. Fig. 47—Terelimella pravitas n.sp.; holotype, X 53.0. Fig. 48—Conjectura congrua n.sp.; holotype, X 21.1. Fig. 49—Trivia aequiflora n.sp.; holotype, X 9.7.
Acteon otamateaensis n.sp. (Fig. 30).
Shell small, spire low, apex truncated; embryo low, nucleus turned inwards and downwards on flat summit of shell. Plait distinct, situated a little below insertion of columella. Narrow almost linear spaced spiral grooves universally developed, the posterior one strongest. Spiral grooves crossed by microscopic axial threadlets. A. wangaloa Finlay and Marwick has the shoulder more sloping and suture not so much cut in; A. oneroaensis Powell and Bartrum likewise has a considerably sloping shoulder with tangential suture, and the spirals less numerous and widely spaced. A. chattonensis Marwick is closely similar to otamateaensis, but has the apical truncation not so marked, and the base not so full; further, chattonensis has spire-whorls smooth and a smooth zone over curve of shoulder on body-whorl.
Height, 4·0 mm.; width, 2·4 mm.
Five specimens collected.
Notoseila clifdenensis n.sp. (Fig. 22).
More attenuate than kaiparaensis, and with the spiral keels different. The two anterior spirals are strong and sub-equal in prominence, the posterior one much weaker. The axials are much better developed, and easily visible under the hand-lens. They are seen crossing spiral interstices as fine threads. Aperture quadrangular, narrowly and obliquely notched anteriorly. Embryo of six smooth whorls, the last two of which are more convex than the earlier ones.
Height, 7·0 mm.; width, 1·2 mm.
Locality: Clifden, Southland, band 6A.
Hochstetteria awamoana n.sp. (Fig. 14).
Shell small, quadrate in outline. The beaks are not terminal, and the shape is different from that of any other described Neozelanic species. The anterior end descends vertically from dorsal margin and is straight, not excavated below. In this respect it rather approaches H. acutangula. Ventral margin broadly and evenly convex; dorsal margin straight, long; posterior one almost straight, obliquely ascending to angulated junction with dorsal. Sculpture of about 14 very thin, threadlike widely spaced radials, and closely spaced, coarser concentric threads, the radials surmounting them. Hinge with a vertically striated area extending along and below anterior half of prodissoconch; behind this begins the ligamental groove which extends posteriorly along hinge; beginning at posterior end of prodissoconch and extending along hinge above groove is another vertically striated area. In adult valves the margin is strongly dentate, and this character along with the outline provides ready separation from other local forms. In the early juvenile shell the margin is entire; as growth proceeds low internal corrugations appear on posterior end immediately below its junction with the dorsal margin; at a still later stage similar corrugations begin to form where the anterior margin merges into the ventral; finally the whole intervening margin of valve comes to be crenated, the first formed corrugations now becoming very strong and dentate.
Height, 3·0 mm.; length, 3·0 mm.
Locality: shell-bed, Target Gully, Oamaru (Awamoan).