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Volume 76, 1946-47
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Tertiary Mollusca from Hokianga District, North Auckland.

[Read before the Auckland Institute, October 29, 1946; received by the Editor, November 6, 1946; issued separately, September, 1947.]

Part I.

The fossils recorded in Part I of this paper were collected several years ago by Professor J. A. Bartrum and Mr. H. J. Harrington during examination of the area lying approximately east of the entrance to Hokianga Harbour. The writer is indebted to Professor Bartrum for his permission to record these fossils and to describe certain species that have been found to be new. Professor Bartrum has again kindly been responsible for the photography.

They come from various localities in the viomity of Waimamaku, the most fruitful of which is located twenty chains above the junction of Taita Stream with Oraora Stream.

Consideration of the list indicates that the beds that have yielded these fossils belong to an horizon that is the equivalent of that developed at Pakaurangi Point, Kaipara Harbour.

The presence of the Turrid genus Awateria in these beds serves to prolong its ancestry, for, the genus is typically a Lower Pliocene one, there being but one species earlier than that, A. defossa Powell, from Upper Miocene rocks in northern Hawkes Bay.

Unless otherwise stated, the holotypes of species described herein are located in the collection of Auckland University College.

List of Fossils.

“P” indicates present also in the faunule at Pakaurangi Point. Kaipara Harbour.

Nucula n.sp.
Nucula sp.
Nuculana (Saccella) aff. arowhana Marwick
Nuculana (Saccella) duplicarina Laws P
Nunculana (Jupiteria) parleachi Laws P
Ledella parkaurangiensis Laws P
Notolepton sp. juvenile
Pleuromeris sp. juvenile
Merelina saginata Laws P
Pareora pinguis Laws P
Pareora cf. pinguis Laws
Sigapatella otamatea Laws P
Polinella cf. scalptus (Marwick) P
Architectonica aucklandica (Marshall) P
Balcis kaiparaensis Laws P
Falsicolus kaiparaensis (Suter) P
Gemmula kaiparaensis (Marshall) P
Bathytoma hokianga n.sp.
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Comitas kaipara Laws P
Zemacies climacota (Suter) P
? Mauidrillia sp.
Mauidrillia fimbriata n.sp.
Inquisitor komiticus Laws P
Awateria expalliata n.sp.
Awateria experta n.sp.
Awateria n.sp.
“Guraleus” sp.
Puha pusula n.sp.
Hokianga nodulata n.gen. n.sp.
Ringicula zecorpulenta Laws P
Cylichnania n.sp.
Vaginella torpedo Marshall P
Dentalium mantelli Zittel P

New Species.

Bathytoma hokianga n.sp. (Plate 55, Fig. 3.)

An elongate biconic shell with sloping, little-excavated shoulders and rather long tapering spire. Of described species it is nearest to B. haasti in sculpture, though not so stout; it lacks the prickly nodules of bartrumi and finlayi. It resembles in form certain Australian species of Micantapex, and when the apex is known it may prove referable to that genus. Shoulder with about 12 primary spirals becoming progressively finer from posterior suture to angulation. Angulation, which is one-third distance from anterior suture, bears three spirals, these closely axially beaded; below angulation there are two or three coarse spirals. Anterior to angulation on body-whorl there are 11 to 12 primary spirals with two or three intervening secondaries. Fasciole strongly developed; beak rather long.

Height: 43mm.; width: 18mm.

There is a closely similar form in Mahoenui beds in the Awakino district, the interstices of the basal spirals of which, however, have 1 to 2 threadlets.

Mauidrillia fimbriata n.sp. (Plate 55, Fig. 6.)

Somewhat similar to M. supralaevis Powell (Awamoan), but with narrower spire, less prickly sculpture, thin sharply elevated spirals and more pronounced marginal spiral. Similar in build to M. clavicula Powell (Awamoan), but with fewer, more widely spaced, and thinner spirals. The swollen subsutural margin carries a sharp, thin spiral thread, and on the penultimate whorl there are two fine threads between this and the angulation, which is tuberculate and situated slightly anterior of mid-whorl. Body-whorl with several spirals on swollen subsutural border, three on shoulder below that and 12 to 14 below angle. Embryonic whorls decollated.

Height: 8.0 mm.; width: 3.0 mm.

Awateria expalliata n.sp. (Plate 55, Fig. 2.)

Shell small, biconic, rather broad in relation to height; spire staged, its height about one-half that of body-whorl. Whorls angled at middle, the angle tuberculate, there being 16 tubereles on body-whorl. Shoulder not steeply rising, faintly concave, weak axials

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crossing it, and with two weak spiral threads close above angle. Suture margined below by moniliform swollen band. Below angle there are two incised spiral lines situated nearer to the angle than to the suture. Below these on the body-whorl there is a broad, unsculptured zone. reaching anteriorly to below level of posterior of outer lip. Anterior to this zone spirals begin to develop again at first as incised lines, later, as the grooves open out, assuming the form of broad ribs. Sinus on shoulder, not deep.

Height: 7.0 mm.; width: 4.0 mm.

Nearest to A. personata Powell (Opoitian), but with fewer axials, which are not crisp as in personata, and though slightly oblique, cannot, be described as arcuate.

Awateria experta n.sp. (Plate 55, Fig. 8.)

Shell small, narrowly biconic, height of spire about, one-half that of aperture. Distinguished from the foregoing species, which it closely resembles in sculpture, by slenderer habit, possession of 5 or 6 distinct spiral threads on shoulder, absence of smooth zone on body, and fewer (only 13) tubercles on body-whorl. There are about 15 distinct primary spiral cords on body-whorl, separated by broad flat-floored grooves, except on neck, where they become crowded. Axials practically obsolete on shoulder; weakly developed and faintly arcuate below (on body).

Height: 9.0 mm.; width: 3.2 mm.

Locality: Waimamaku River, sandstone with lenses of fine conglomerate and shell grit, ¼ mile below junction of Taita Stream with Waimamaku River.

Awateria n.sp. (Plate 55, Fig. 5.)

Close to experta n.sp., but with whorls higher in relation to width, and shoulder more sloping. The spiral sculpture is coarser and consists of distinct, spaced cords below angle of whorls and on body. Spirals on shoulder almost obsolete and sinus deeper than that of expalliata and experta. Axials on body 14 in number, practically obsolete on shoulder of whorls, existing as weak undulations on body-whorl, where they evanesce earl3* on base. Spirals on body-whorl 14 in number, distinctly raised, separated by flat interspaces whose width is greater than that of the ridges.

Height: 8.0 mm.; width: 3.6 mm.

Puha pusula n.sp. (Plate 55, Fig. 7.)

Shell small, biconic, height of spire a little less than that of aperture; outlines straight, sutures indistinct. Periphery of whorls of spire situated low down close to suture, that of penultimate whorl a little anterior of middle. The peripheral spiral is tuberculate, there being 14 tubercles on penultimate whorl. There is a weaker subsutural spiral which is cut into beads, these corresponding axially with the tubercles of the periphery. Between these two spirals there is a broad, excavated, unsculptured zone on which is situated the sinus. Body-whorl with 8 to 10 thin, low, primary spirals below periphery, weaker interstitial secondaries usually present. Protoconch typical, similar to that of Puha sinusigera Powell. Pillar plications not in evidence.

Height: 8.5 mm.; width: 4.0 mm.

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Locality: Sandstone with lenses of fine conglomerate and shell grit about ¼ mile below junction of Taita Stream and Waimamaku River.

Of described species hebes (Hutton) is closest to this new species in general form, but is readily separable in that the angle is near mid-whorl on the spire and not low down like that of pusula. Other differenced are not wanting.

Genus Hokianga nov.

This new name is provided to accommodate a small shell whose relationships are obviously with the Daphnellinae. The protoconch, which is a daphnellid one, is conical and consists of 3 to 4 lightly convex whorls with typical reticulation. The sinus also is daphnellid, located at the suture, and crossed by close hair-like, curved axials. The sculpture, however, is outstanding in that the biangulate whorls are crossed by sharply nodulated axials giving a notably prickly effect, much as in Echinoturris finlayi (Powell).

Certain Recent Australian species (e.g. Daphnella aculeola Hedley) seem referable to this group on the basis of general build, apex, and suture.

Genotype: Hokianga nodulata n.sp.

Hokianga nodulata n.sp. (Plate 55, Fig. 1.)

Shell small, elevated, height of spire equal to that of body-whorl. Whorls convexly biangled, crossed by axial ribs separated by grooves of about the same width as the ribs. Axials end abruptly at margin in sinus area. Whorls of spire with two heavy and with much weaker alternating spirals (three), the strong spirals sharply nodulating the axials in prickly fashion. Axials (18 on body-whorl) die out low down on base, where they are crossed by numerous fine close spiral threads, which are developed right ont on to beak. Anterior canal short. Other characters are included in the generic description.

Height: 9.3 mm.; width: 3.0 mm.

Part II.

The mollusca recorded below were collected recently at Mitimiti, north of Hokianga Harbour, by Mr. H. J. Harrington, to whom the writer is thankful.

The locality is more richly fossiliferous than the Subjoined list shows, for the friable nature of the sandy and gritty matrix has permitted considerable decalcification of much of the shelly material.

The beds, as the list of fossils indicates, are referable to the same horizon as that of the fossiliferous strata to the south of Hokianga Harbour (Part I of this paper), and thus correlate with the sandstones at Pakaurangi Point, Kaipara Harbour.

Record of Fossil Mollusos from Mitimiti.

“P” indicates found also at Pakaurangi Point.

Nucula otamatea Laws P
Nuculana (Saccella) duplicarina Laws P
Nuculana (Jupiteria) parleachi Laws P
Acar harringtoni n.sp. P
Monia kaiparaensis Laws P
Picture icon

Fig. 1.—Hokianga nodulata n gen n sp. × 6.8
Fig. 2.—Awateria eapalliata n.sp. Holotype, × 6.8.
Fig. 3.—Bathytoma hokianga n.sp. Holotype, × 1.1.
Fig. 4, 9.—Acar harringtoni n.sp. Holotype, × 6.9.
Fig. 5.—Awateria n.sp. × 6.8.
Fig. 6.—Mauidrillia fimbriata n.sp. Holotype, × 6.8.
Fig. 7.—Puha pusula n.sp. Holotype, × 6.8.
Fig. 8.—Awateria eaperta n.sp. Holotype, × 6.8.

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Modiolus n. sp
Lima n.sp.
Ostrea sp.
Myrtea valdesculpta Marwick ?P
Pteromyrtea auriculata (Bartrum) P
Notocorbula innerans Laws P
Maurea sp.
Fautor cf. marwicki (Finlay) P
Zeminolia cf. ordo Laws
Rissoina (Zebinella) heterolira Laws P
Ataxocerithium cf. simplex Marwick P
Opimilda kaiparaensis (Laws) P
Taniella notocenica (Finlay) P
Agathirses sp.
Paracominia macphersoni Marwick
Cylichnania bartrumi Marwick P
Vaginella torpedo Marshall P
Dentalium mantelli Zittel P
New Species.

Acar harringtoni n.sp. (Plate 55, Figs. 4, 9.)

This species is closely related to A. sandersonae Powell (Recent). In general outline, position and fullness of beaks there is little difference, except that the ratio height: length is somewhat the greater in the Recent species. The hinge and teeth of harringtoni are slightly heavier. Certain sculptural difference, however, allows ready separation. The radials of the fossil are thin and are spaced at intervals that are greater than their own width, whereas the radial ribs of sandersonae are coarse and spaced less than their own width apart. Sandersonae has the scales or beads at intersections of the two elements of sculpture much coarser than those of harringtoni.

Height: 5.6 cm.; length: 9.0 mm.; inflation (1 valve): 3.0 mm.

Holotype in writer's collection.

Occurs also in the beds at Pakaurangi Pomt.

Modiolus n.sp.

This record is based on what is practically a cast of a considerably decorticated specimen. The form, however, is preserved, and it is seen to be distinct from species so far described.

Lima n.sp.

This shell is characterised by numerous (28) close-set radial ribs, their flanks convex, as are those of L. waipipiensis Marshall and Murdoch, those of L. colorata Hutton being vertical. The specimen is small and larger shells may yet be found.

New Locality.

Myrtea valdesculpta Marwick.

1944. Myrtea valdesculpta Marwick, Trans. Roy. Soc. N.Z., Vol. 73, p. 185, Pl. 26, Figs. 16, 22; Pl. 27, Fig. 29.

There are several shells that provide no satisfactory means of separation from this common South Island Awamoan species. Two small specimens, probably of this species, have been obtained at Pakaurangi Point, Kaipara.