The Molluscan Fauna of the Pahi Greensands, North Auckland
[Read before Wellington Branch. June 10, 1948; received by the Editor, June 16, 1948.]
The relationship between the fossiliferous pebbly greensands and the “hydraulic” limestone (Onerahi Series) at Pahil Peninsula and nearby Kaipara localities has been the subject of accounts by Marshall (1924), Ferrar (1934), Henderson (1936) and Bartrum (1937), and remains one of the controversial topics in the stratigraphy of North Auckland. The present paper is concerned solely with a revision of the fauna of the greensands and the systematic description of new forms.
Material. The collections examined include Geological Survey collections Nos. 544, Pahi, Kaipara Harbour, J. Park, 1885; 732, Pahi township, A. McKay, 1887; some of Dr P. Marshall's collections, and those made by Ferrar during the geological survey of Dargaville-Rodney Subdivision. The above are lumped as Pahi General Collection. Most are undoubtedly from the shores of Pahi Peninsula itself, but Dr Marshall's collections may contain specimens from Coates' Landing, Hukatere Peninsula, and Jackman's Landing, Whakapirau, where similar beds occur (Marshall, 1917, p. 440). Additional collections are available from Pahi (G.S. 3327, H. J. Harrington, Dec., 1942, and 3292, J. Healy and C. A. Fleming, Jan., 1944) and from Coates' Landing (G.S. 3289, C.A.F., Jan., 1944). The lithologies and faunas are the same in all collections and there is nothing to show that the several pebbly greensands are not the same general horizon. So far as is known, all the Pahi collections were made from greensands south of the appearance of the hydraulic limestone on the beach on the west shore of Pahi Peninsula. Fossils have been noted from greensands north of the limestone on the west coast of the peninsula (Ferrar, 1934, p. 42), but none so localized as have been studied.
Age and Correlation of the Pahi Greensands. The present survey has not brought forward any reason to alter the assignment of the Pahi greensands to the Eocene (Marwick, 1931, p. 3; and in Ferrar, 1934, p. 35). Of the Eocene stages represented by mollusean faunas elsewhere in New Zealand the Kaiatan is known from few localities and faeies so that allocation of the Pahi fauna to the Bortonian rather than to the Kaiatan depends to a certain extent on the presence of key species belonging to genera perhaps absent from the Kaiatan only because of facies limitations. Subsequent study of the mollusca has emphasized their affinity with faunas of accepted Bortonian horizons at Hampden, Waihao, Kakahu and elsewhere in the South Island. There are virtually no mollusean faunas from the Lower Eocene and Paleocene stages recently established on microfaunal evidence (Finlay and Marwick, 1947), and few if any of the differences between the
Pahi fauna and standard Bortonian faunas can be interpreted as evidence for older age of the former. Although an age older than Bortonian cannot be ruled out, the Pahi greensand fauna has no clear affinity with the Matau fauna (Finlay and Marwick, 1937) which is believed to be older than Bortonian, but younger than Wangaloan (Danian).
The molluscan evidence for Bortonian age may be summarized: (1) The genera, Monalaria and Speightia and the subgenus Kakahuia are so far known only from Bortonian horizons. In the case of the first, the Pahi shell is specifically very close to the typical Bortonian, M. concinna Suter. (2) The species Limopsis campa Allan, Lopha gudexi Suter, Venericardia bartrumi n.sp., Offadesma marwicki n.sp., Magnatica fons Fin., Waihaoia suteri (Maw.) are elsewhere known only from Bortonian beds, although the identifications are not in all cases positive. The species Notogenota pahiensis Pow. has its nearest relation. N, gonioides Suter, in the Bortonian of the South Island.
The genera Neilo and Sigapatella have not previously been recorded from rocks older than Oligocene, but the extension of their ranges back into the Eocene does not involve any difficulty. Serripecten has not been recorded prior to the Kaiatan in the South Island, but a species [S. tioriensis (Marwick)] has been described form beds at the Chatham Islands with a Paleocene microfauna (Mangaorapan stage, Finlay and Marwick, 1947, p. 231).
Finlay and Marwick (1937, 1940) have given the evidence for a middle Eocene age for the Bortonian. Marwick has subsequently (1942) described Keilostoma malingi, closely related to the European K. minus (Desh.) [Ypresian to Auversian] and to the Californian Keilostoma n.sp. [from the Domingene] (Clark and Vokes, 1936). The Bortonian nautiloids (Fleming, 1945) also point to a Ypresian-Lutetian age. and. in the Pahi fauna, Venericardia healyi n.sp. is allied to V. acuticostata (Lik.) of the Paris Basin (Lutetian-Auversian) and to species in the Ypresian-Lutetian beds of India (Laki and Khirthar Groups). The evidence for the Middle Eocene (approximately Lutetian) age of the Bortonian is thus increasing.
The Fauna of The Pahi Greensands
General collection, including G.S. Localities 544 and 732 and Dr Marshall's collection.
G.S. Localities 3292 and 3327, Pahi Peninsula, West Shore.
G.S. Locality 3289, Coates' Landing, Hukatere Peninsula.
|Nucula cf. sagittata Suter||X||A|
|Nuculana (Saccella) semiteres (Hutton)||X||X||A, B|
|Nuculana (Saccella) pahiensis n.sp.||X||X||A|
|Nuculana (Jupiteria) ferrari n.sp.||X||X||A|
|Neilo cf. sinangula Fin.||X||A|
|Cucullaea cf. waihaoensis Allan||X||X||A, D|
|Limopsis cf. campa Allan||X||X||A. D|
|Serripecte n.sp. aff. tioriensis Marwick||X||C|
|Cubitostrea gudexi (Suter)||X||X||A, B|
|Pinna cf. distans Hutton||X||X||A, B, D|
|Venericardia healyi n.sp||X||X||C|
|Venericardia bartrumi n.sp||X||X||A, D|
|Lucinoma arapaoa n.sp||X||X||A, D|
|Divaricella (Divalucina) notocenica King||X||A|
|“Angulus” pahiensis n.sp||X||X||A|
|Finlayella marshalli n.sp||X||X||X||A, D|
|Dosinia (Kakahuia) n.sp||X||A, D|
|Marama (Hina) sp.||X||X||X||D|
|Hedycardium brunneri (Hector)||X||A|
|Notocorbula aff. humerosa (Hutton)||X||A|
|Offadesma marwicki n.sp||X||A|
|Panope worthingtoni Hutton||X||X||X||A, B, D|
|Zeacolpus n.sp||X||X||X||A, B|
|Monalaria concinna (Suter)||X||X||A, B|
|Sigapatella n.sp. aff. mapalia Marw||X||X||X||A, B|
|Magnatica. cf. fons Finlay||X||X||A, B|
|Cypraea (? Eocypraea) murdochi n.sp.||X||B|
|Cypraea (? Bernayia) n.sp.||X|
|Tatara pahiensis (Marshall)||X||A|
|Falsicolus n.sp. cf. allani Fin||X||X||X||A|
|Falsicolus cf. solidus Suter||X||A|
|Waihaoia suteri Marw||X||X||X||A, B, D|
|Eoturris cf. neglectus (Suter)||X||A.|
|Marshallaria, aff. spiralis (Allan)||X||A|
|Notogenota pahiensis Powell||X||X||A|
|Speightia spinosa (Suter)||X||B|
|Acteon cf. n.sp. B. (Finlay & Marwick, 1937)||X||A|
|Aturia (Brazaturia) n.sp||X||A, D|
|Laevidentalium cf. pareorense (P. and S.)||X||A|
|Carcharodon auriculatus (Blainville)||X||G|
|Odontaspis elegans (Agassiz)||X||C|
Facies and Conditions of Deposition. There are a number of different facies within the Pahi greensands at both localities, and some of the molluscan species are restricted to one or more of such facies. In the faunal list the lithology with which each species was associated is indicated by the following symbols:
Calcareous glauconitic silty sandstone.
Hard calcareous concretionary bands in A.
Coarse conglomerate with pebbles of dark green and black argillite in a gritty calcareous cement.
Shell rock; tightly packed mollusca in moderately hard glauconitic sandy limestone.
Tim fauna of A includes such forms as Nuculana, Divaricella, the Tellinidae, Hedycardium, Offadesma, Sigapatella, Austroassia, Galeodea, Falsicolus, Turridae, Act eon, suggesting sublittoral euraline waters of moderate depth, perhaps about 10 to 25 fathoms.
The concretions (B) have formed around cores of shell material probably in much the same way as noted by Bartrum (1917) in recent sediments at similar depths. Facies C and D represent current-scoured channels at similar depths, such as have been mapped by Powell (1937) in the Waitemata Harbour. Indeed, a shell-rock composed chiefly of Venericardia n.sp. represents conditions closely akin to his Venericardia-Tawera association, while the conglomeratic lenses (C) with a fauna of Serripecten, Venericardia, and pelagic sharks, are more suggestive of benthic conditions with strong bottom currents caused by tidal flow in confined channels (comparable with Powell's bottom formations, 3 to 3c) than of littoral deltaic conditions. Finlay (1939, p. 521, p. 538) has presented micropalaeontological evidence for the upper (= true) Bortonian age of the Pahi white marl, outcropping only half a mile from the greensands and associated rocks. If the greensands and marl are contemporaneous, the latter finegrained calcic facies represents a deeper deposit, below the limit of effective operation of bottom currents and waves, and the presence of such a rock as the lateral equivalent of the nearby sublittoral greensands and conglomerates emphasizes the poverty of terrigenous material supplied to the Bortonian seas. Conditions for the formation of glauconite are also claimed (Galliher, 1935) to occur where the deposition of marine sediments is slow in depths of 10 to 50 fathoms, so that the Pahi greensands may be considered merely a local bathymetric variant of the widespread fine-grained deeper-water sediments comprising part (at least) of Ferrar's Onerahi Series, the distinction being due more to their relations to the wave base than to differences in the supply of sediment.
One further stratigraphical implication may be noted. Ferrar (1934, p. 35) mapped the Pahi greeusands, and other similar rocks (see, for example, a note under Lopha gudexi Suter below) in his Whangarei Series and then used the Pahi fauna as evidence of the Eocene age of part of that series. The Whangarei Series, as typically developed, consists of basal coal-measures unconformably overlying older rocks followed by a marine sequence and, though there is little definite faunal evidence of the age of the Whangarei beds, it is probable that their basal members represent, in North Auckland, the Whaingaroan (mid Oligocene) transgression so widespread in South-West Auckland. The Whangarei beds certainly follow the Onerahi sediments after a period of non-deposition, possible injection of peridotites, and erosion, and the association of the Pahi Eocene green-sands with the Onorahi beds allows such a period (the Kaiatan Stage, Upper Eocene) for elevation prior to the Whaingaroan transgression.
Finlay and Marwick (1940, pp. 109, 110) have noted the rarity of Kaiatan (“Tahuian”) sediments in the North Island, and it is possible, in view of the above considerations, that the early Tertiary orogeny in North Auckland (Bartrum and Turner, 1929) may prove to fill the gap in North Auckland stratigraphy representing the Tahuian and Kaiatan Stages (now considered synonymous) of the Upper Eocene.
Nuculana (Saccella) semiteres (llutton)
Many specimens, somewhat variable in shape, cannot be distinguished on any constant feature from topotypes of belluloides Allan ( = semiteres Hutton). They tend to have about one more concentric ridge per millimeter on the body of the shell than have McCullough's Bridge specimens, which, however, develop coarser sculpture marginally.
Nuculana (Saccella) pahiensis n.sp. (Pl. 24, figs. 2, 3)
Shell small, inflated, with a short, rapidly tapering rostrum. Umbones high, at anterior third. Anterior dorsal margin convex; posterior dorsal margin concave, but flattening to form a slight flange above the rostrum. Posterior area broad, concave, and well defined by a rounded angular ridge descending from umbo and rising to beak. Lunnule indicated only by dying of seulpture anteriorly. Sculpture of coarse, fairly regular, spaced, concentric, rounded ribs, 6 to 7 per mm., with interspaces of equal width, retracted and dying out anteriorly, sharply retracted over the rostral ridge and stopping on the posterior area except for a few (about one in five) which cross the area. Ventral to the beak the ribs are faintly re-entrant. Interior and dentition not seen.
Height, 8 mm.; length, 9·5; inflation (1 valve), 3 mm. (holotype).
Ancestral to the Southland Series N. waikohuensis Marwick and Taranaki Series onairoensis Marw., but with the beak less upturned than in the former, with finer sculpture, and with a narrower and simpler posterior area than in either Miocene species.
The strength of the concentric ribbing varies somewhat, as illustrated, but it would appear that only one species is represented.
Nuculana (Jupiteria) ferrari n.sp. (Pl 24, fig. 1)
Of the specimens available, many have suffered distortion, and the range of shape is considerable. Undistorted shells broadly ovate, bluntly tapered posteriorly, without rostrum. Umbones low to moderately high, slightly in front of middle; anterior end rounded. Dorsal margins gently concave; lunule ill-defined and narrow; posterior area convex, not defined. Sculpture: strong, regular, rounded, concentric ridges, with shallow but well-defined interstices about half as wide, 3–4 per mm., finer on umbones; maintaining their strength anteriorly but weakening abruptly towards the lunule. Hinge fairly narrow and weak; 15–17 teeth behind. 10–14 in front of the resilium pit, towards which they decrease rapidly in size. Chondrophore and pallial sinus not seen. Height, 8·5; length, 12; inflation (1 valve), 3 mm. (holotype, G.S. 3289). Height, 10; length, 17 mm. (largest paratype, 3289).
This large species is probably ancestral to, and certainly congeneric with, Nuculana ellisi Marwick (Upper Miocene), which Finlay (1926, p. 445) placed under Saccella, but which, in view of its ill-defined, bluntish rostrum is best regarded as Jupiteria, as hinted by Marwick (1931, p. 51) in describing N. (Jupiteria) leachi. Further group names are desirable in the somewhat unwieldy genus Nuculana, but this must await a broader survey than is possible at present.
Neilo cf. sinangula Finlay
One imperfect cast is a true Neilo and is of interest in extending back the range of the genus. Finlay and Marwick (1937, p. 17) noted that the genus had not been reported in New Zealand before the “Ototaran” (= Duntroonian) of Wharekuri. The Pahi material does not permit detailed specific comparison, but the specimen is a typical Neilo and in no way intermediate between Neilo and the Wangaloan Spineilo.
Serripecten n.sp. aff. tioriensis Marwick
Shell small for genus, moderately inflated, the left valve slightly less than the right, equilateral. Right valves: 38–40 broad spaced primary radials with interspaces about half their width begin about 10 mm. from apex. In the centre of the shell fine secondary riblets appear between the primaries at 25 mm., but later in front and behind, and do not become more than half as strong as the primaries at the edge of the valve (35 mm.). Scales on primaries distally, and also on distal portions of secondaries. No tertial riblets. Ears subequal; posterior with 5–6 ribs, anterior ear worn. Left valve (incomplete) with similar number of primary ribs; few secondaries even at margin (32 mm.) on one valve, but starting earlier (25 mm.) on another.
Height, 33 mm.; length, 37·5 mm.; inflation, 8 mm. (right valve).
Named species with affinity are tioriensis Marwick, which has less advanced secondary ribs; enfielddenis Marwick, which has fewer primaries, more advanced secondaries, and tertial riblets marginally (in one left valve); and tahuiana Laws, with fewer primaries, and earlier developing (i.e., more advanced) secondaries. As Dr Marwick has a review of this difficult genus in preparation, no name is bestowed, but a description is given for reference. If the sculptural development is any indication of stratigraphical position, the Pahi shells fall between tioriensis Marwick (Mangaorapan) and tahuiana Laws (Kaiatan).
Genus Cubitostrea Sacco
1807. Sacco, in Bellardi and Sacco, Moll. Terr. terz. Piemonte e Liguria, 23, 12. Type (by original designation): Ostrea cubitus Deshayes (Upper Eocene, Auversian, France).
Finlay located the New Zealand Eocene Ostrea gudexi Suter in Lopha Bolten, of which the type, O. cristagalli (Gmel.), is an extreme strongly folded shell. A better location is in Cubitostrea, currently used for early Tertiary oysters with asymmetrical shells, strongly
ribbed left valves and relatively smooth right valves. Complete individuals of gudexi occur at Kakahu, with typical radially sculptured left valves and smooth right valves; no sculptured right valves have been seen.
Cubitostrea gudexi (Suter)
1917. Ostrca (s.str.) gudexi Suter, N.Z.G.S. Pal. Bull. 5, 71, pl. 8. fig. 2 (Kakahn).
1921. Ostrea gudexi Suter: Marshall and Murdoch, T.N.Z.I., 53, 77, pl. 15, fig. 1 (Pahi).
1928. Lopha pahicnsis Finalay, T.N.Z.I., 59, 266.
Finlay proposed the name pahicnsis on the basis of Marshall and Murdoch's comparison of Suter's paratypes, which have “seven to eight” and “fifteen or more” radial ribs, with Pahi specimens with “nineteen to twenty ribs.” Pahi and Kakahu specimens both show much variation, to a certain extent depending on size and shape; specimens with fifteen or fewer ribs are as common at Pahi as at Kakahu and there is little justification for maintaining Finlay's separation; unlocalized specimens could never be identified.
Cubitostrea gudexi appears to be confined to the Bortonian Stage; and is recorded from the following localities:
Kakahu, S. Canterbury, greensands underlying limestone (type locality).
Blands Bluff and Hinds, Mt. Somers District (Speight, 1938, pp. 59, 60).
Pahi Greensands, Kaipara, North Auckland.
Onerahi Pa, Whangarei.
The specimen from Onerahi Pa comes from a calcareous glauconitic sandstone included by Perrar (1925, p. 43) in the Whangarei Formation, but dipping strongly towards rocks mapped as Onerahi Formation which are also mapped along the strike and topographically higher than the patch of “Whangarei” beds. Not far away, on the other coast of Onerahi Peninsula, is the conglomerate in greensands described by Bartrum (1921, p. 128) and included in the Onerahi Formation by Ferrar (op. cit., p. 36). It seems probable that both the fossiliferous and conglomeratic greensands at Onerahi represent the Pahi pebbly greensands of the Kaipara, and like the latter may underlie hydraulic limestone.
Pinna cf. distans Hutton
The Pahi specimens are good casts, showing a diamond-shaped cross-section and a longitudinal groove which are merely generic features, and having the shape and sculpture of Hutton's type from Caversham. In New Zealand the genus first appears in the Piripauan (Pinna sp., Woods, 1917, p. 28) and apparently became extinct after the Awamoan. It is uncertain when Atrina first appeared, but middle Miocene “Tutamoe” specimens (Marwick, 1931, p. 60) are Atrina. Hutton's lata (Cobden, Whaingaroan) is apparently a Pinna, with a suleus, judging from the Awamoan shell figured by Murdoch (1924). Pre-Nukumaruan Atrinas are frequently obtuse and expanded
posteriorly like lata and have coarser concentrie growth folds, extending further ventrally than in the Pliocene-Recent Atrina zelandica (Gray).
Venericardia healyi n.sp. (Pl. 24, fig. 11)
Shell of moderate size, strong, subquadrate, inflated; umbones at anterior quarter. Imnule small, depressed, defined anteriorly by a shallow groove, not retracted below. Escutcheon (left valve) not developed; posterior area gently concave. Sculpture, 30–33 spinous radial ribs, with narrower deep interstices in the adult; regularly increasing in strength from postero-dorsal margin to the eighth, which is strong and defines the posterior area, subequal and spaced on body of shell, finer towards lunule. On the holotype, ribs on the posterior area have a faint secondary riblet clinging to their posterior flanks; on the seventh, eighth, eleventh, and twelfth ribs (from behind) such secondaries are stronger but not spinous; from the seventeenth to twenty-fourth the posterior secondaries are weaker, but anterior secondary riblets have appeared, and, in the anterior half of the shell, the ribbing is tripartite, each strong spinous rib having a lesser beaded riblet on either side. Interspaces with fine growth lines. Hinge plate heavy (paratype, left valve, worn), a slightly arched posterior cardinal, and a knob-like anterior cardinal separated from the lunule by a triangular depression.
Height, 25 mm.; length, 29·5 mm.; inflation (1 valve), 12 mm.
Locality: Pahi, in limy conglomerate bands only.
The New Zealand Eocene Venericardia species do not appear to be derivatives of the Wangaloan (Danian) V. fyfei Finlay and Marwick. The relationship between healyi, acanthodes Suter, and new species from Waihao with the Tethyan V. beaumonti d'Arch stock (Danian) and derivative Eocene forms such as acuticostata Desh. is much closer than is either group to fyfei. There was apparently a renewed invasion of tripartite ribbed stock from the north after the development of fyfei, presumably from an earlier immigrant from the same source (Finlay and Marwick, 1937, p. 27). Triple tuberculate radials have survived to a varying extent in New Zealand Eocene forms which are probably derived from some beaumonti-like stock. In healyi the tripartite ribs are best developed and evenly beaded. V. acanthodes Suter is based on a trigonal heavily hinged shell which may be gerontic and abnormal, since it has not again been collected, but which shows faint secondary riblets bordering some of the 22 primary radials. The common Waihao form (including Suter's paratypes of acanthodes) is closer to healyi in shape, but has 24 narrow radials with wide interspaces and faint margining secondaries more or less confined to young stages. The Oligocene V. benhami Thompson and later spinous ribbed species of Venericardia have lost the secondary riblets, but that the pattern has a persistent structural basis is suggested by the reappearance of faint secondaries on weathering in a senile V. subintermedia Suter from Clifden.
Tripartite ribs suggesting derivation from the widespread Danian V. beaumonti have persisted in numbers of Paleocene and Eocene
Venericardia throughout the world, but the character does not seem to have survived into the Oligocene. Apart from their occurrence in Paleocene species, such ribs are present in acusticostata Lk. (Paris, Lutetian-Bartonian), globosa Sow. (Bartonian), alticostata Harris and fungina Harris (Claiborne, Lutetian-Auversian), funiculosa d'Arch. and Haime and related forms (Laki and Khirthar of India). The genotype of Venericardia, imbricata Gmelin (Paris, Ypresian-Lutetian) lacks all but occasional faint traces of such secondaries. No post-Eocene species have been noted possessing tripartite ribs and the feature was apparently lost by the several Tertiary lineages which developed from common Eocene stock throughout the world. V. healyi is quite close to acuticostata Desh, and the two species may not be far separated in time. Stewart (1930) was inclined to locate acuticostata in his subgenus Glyptoactis, but the writer hesitates to use that subgenus, based on the American Miocene hadra Dall, for the New Zealand Eocene species, since the latter (and acuticostata) are probably as closely related to imbricata as to hadra.
Named after Mr J. Healy, N.Z. Geological Survey, who collected the type specimens with the writer in January, 1944.
Shell similar to V. healyi n.sp., but much smaller, higher, with about 19 tripartite radial ribs, angular, not scaly, the secondary riblets fine and on the flanks of the primaries.
Height, 13 mm; length, 12 mm.; thickness (2 valves), 10 mm.
Certain gritty bands at Pahi are closely packed with badly leached specimens of small Venericardia which are not the young of healyi n.sp. as they occur in large numbers together and have a sculpture which cannot be matched in young stages of that species.
Venericardia (Venericor) bartrumi n.sp. (Pl. 24, fig. 13)
Shell almost round, of medium size, strong. Beaks at anterior third. Lunule apparently smooth, but decorticated, bounded by a groove, not retracted. No escutcheon, nor defined posterior area. Sculpture, 24 flatly rounded broad ribs, strongest on the body of the shell, becoming finer towards lunule, separated by interspaces as wide as ribs in young stages, less than half the width marginally, on all but anterior quarter of disc, where ribs and interspaces are of equal width. Concentric sculpture represented by growth lines causing rounded low folds on ribs. Hinge not seen.
Height, 30 mm.; length, 30 mm.; inflation (1 valve), 9 mm.
Localities. Type and paratype from Pahi (General Collection); also from G.S. 3210, conglomerate band, base of Bortonian, Otaio Gorge (Opihi S.D.), and 2119, Waihemo S.D. (Bortonian).
This species is possibly of the same lineage as V. pseutella Marwick, V. awamoaensis (Harris) and other Oligocene-Miocene forms in which the smooth squarish ribs of bartrumi have become rounded and the lunule retracted accompanying changes in shape. In the Holarctic Eocene the assemblage of species centering around N. planicosta Lk., genotype of Venericor Stewart, 1930, are allied in sculpture, but have the lunule retracted, and the provisional location of bartrumi in Venericor merely serves to emphasize the early divergence of two
groups of Venericardia which were established in New Zealand, as elsewhere, in Eocene times.
Named in recognition of Professor J. A. Bartrum's researches on North Auckland stratigraphy.
Loripinus (? Eophysema) arapaoa n.sp. (Pl. 24, figs. 6, 7)
Shell of moderate size for the genus, strongly inflated, orbicular but somewhat depressed, fairly solid, equilateral. Sculpture of irregular, low, concentric growth folds; faint radials on body of shell, only when weathered. Anterior wing (on right valve) defined by a shallow sulcus running forward from below the beak. Lunule ill-defined, linear. Ligamental groove lanceolate, with inward sloping walls. Interior not seen, but casts show typical lucinid anterior adductor scar, fine radial sculpture, and an ill-defined weak ridge from umbo to posterior ventral margin.
Height, 33 mm; length, 40 mm. (estimated); inflation (2 valves), 25 mm. (holotype). Height, 51 mm.; length, 53 mm. (largest paratype).
This type of lucinid has not previously been recorded from New Zealand, but additional species as yet undescribed occur in the Miocene and reach over twice the size of the present species. The type of shell represented was of wide distribution in the Tertiary, and is still widespread in warmer seas. More precise affinities for arapaoa are difficult to determine without the hinge. The muscle scar is closer to that figured by Chavan (1938, p. 118) for Anadontia (= Loripinus) than for Pegophysema Stewart, but the ligamental arrangement seems closer to that of the latter group. The Eocene Eophysema Stewart (type, L. subvexa Conrod) has similar shape, has radial sculpture which is perhaps (from Harris's figures, 1919, pl. 38, figs. 1–5) due to wearing: one of the Pahi paratypes shows fine radials, so that subgeneric location is tentatively made in Eophysema.
“Angulus” pahiensis n.sp (Pl. 24, fig. 5)
Shell of moderate size, subequi valve, inequilateral, beaks at posterior third; prosogyrate. Anterior end produced, broadly rounded in front, dorsal margin straight near beaks but convex behind. Posterior end with a convex steeply sloping dorsal margin. Rostrum ill-defined, roundly truncated. A weak fold bounds the rostrum below on right valve, but has not been seen on the slightly inflated left valve. Slight escutcheon on left valve. Sculpture: concentric growth lines on proximal two-thirds of shell, marginal sculpture of flat-topped concentric ridges with linear interspaces, about 4 per millimeter, but irregular in width. Pallial lines not preserved. Hinge (right valve, paratype): nymph strong, arched; posterior Iateral absent, cardinal broken, but anterior cardinal apparently weak; anterior lateral strong, lamellar, straight.
Height, 19 mm.; length, 32 mm.; inflation (2 valves), 8 mm. (holotype). Height, 23 mm.; length, 37 mm. (paratype).
This shell is apparently congeneric with Angulus (Peronidia) inflata Laws (Pakaurangi, Miocene), Maoritellina fragosa Marw. (Tutamoe Series, Miocene) and perhaps Macoma hesterna Powell and Bartrum (Waitemata Series, Miocene). In those species the beaks are posterior and in at least the first two are directed forward. In Maoritellina the beaks are opisthogyrate, as in most Tellinids, and the hinge, with the right anterior lateral barely separated from the anterior cardinal, is very different from that of pahiensis, which is quite similar in dentition to Angulus (Peronidia) edgari (Iredale). The distinctive features are worthy of systematic recognition, but this can be postponed until a species with full hinge details is available.
Finlayella marshalli n.sp. (Pl. 24, fig. 4)
Shell large for genus, sub-equilateral, equivalve, beaks median. Anterior and posterior dorsal margins convex, descending with equal rapidity, the latter to a weakly-angled rostrum; poorly defined by low fold on right valve. Sculpture: fine concentric growth lines; on the dorsal and ventral margins stronger concentric linear grooves divide the surface into ribs as in last species. Interior not seen.
Height, 15 mm.; length, 22 mm.; inflation, 3 mm. (holotype, left valve).
As the interior has not been seen, the generic placing is based chiefly on shape and is tentative. The species is named after Dr P. Marshall, whose early collections at Pahi form an important part of the material studied for this paper.
Dosinia (Kakahuia) n.sp.
A single, poorly-preserved left valve is an exact match, in its characteristic roundly trigonal shape, to D. (Kakahuia) suteri Marw., but differs in having a more lightly built and arched hinge plate, with the teeth more divergent, approaching Kereia, and with a sculpture which was apparently of concentric ridges rather than lamellae. Probably a new species of Kakahuia is represented.
Offadesma marwicki n.sp. (Pl. 24, fig. 10)
Specimens of Offadesma in the Geological Survey collections from Awamoan and higher horizons show no recognizable differences from New Zealand shells attributed to O. angasi (Crosse and Fischer), the Recent species,* No Lower Oligocene specimens have been seen, but specimens from G.S. Loc. 176, Black Point, Waitaki Valley (Bortonian), are squatter, less depressed dorsoventrally, and are much more equivalve, the left valve having about three-quarters as much inflation as the right, whereas, in angasi, the left valve is only about half as inflated as the right.
Height, 34 mm.; length, 43 mm.; inflation (2 valves), 20 mm. (holo-type, Black Point, Waitaki Valley).
[Footnote] * The type locality of O. angasi is Spencer Gulf, Australia. Available specimens suggest that New Zealand Offadcsma may be systematically differentiated from at least the Tasmanian form, but fuller series are required.
fig. 1—Nuculana (Jupiteria) ferrari n.sp. Holotype. 12 X 8.5 mm.
Fig. 2—Nuculana (Sacella) pahicnsis n.sp. Holotype. 9.5 X 8 mm.
Fig. 3—Nuculana (Saccclla) pahiensis n.sp. Paratype. 9 X 6.7 mm.
Fig. 4—Finlayella marshalli n.sp. Holotype. 22 X 15 mm.
Fig. 5—“Angulus” pahiensis n.sp. Holotype. 32 X 19 mm.
Figs. 6, 7—Lucinoma arapaoa n.sp. Holotype. 33 X 34 mm.
Figs. 8, 9—Tatara revolutum (Finlay). G.S. 1982, Gees Point. Kakanui. 37 X 19 mm.
Fig. 10—Offadesma marwicki n.sp. 43 X 34 mm.
Fig. 11—Venericardia healyi n.sp. Holotype. 29.5 X 25 mm.
Fig. 12—Tatara pahiensis (Marshall and Murdoch) n.gen. Holotype. 40 X 24 mm.
Fig. 13—Venericardia (Venericor) bartrumi n.sp. 30 X 30 mm.
Height, 35 mm.; length (estimated), 46 mm.; inflation (2 valves), 19·5 mm. (paratype).
Height, 53 mm.; length, 78 mm.; infiation (2 valves), 28 mm. (angasi, Mercury Bay, Recent).
A single crushed Pahi specimen agrees with the types in outline.
A further locality is G.S. 41, black limestone, Tokomairiro, 1863.
The Pahi material is a single shell firmly embedded in matrix and showing only the interior. It represents a species akin in its broadly ovate and highly elevated conic shape to the Kakanui breccia (Whaingaroan, Oligocene) form once listed (in error) as F. wannonensis Harris (see Finlay, T.N.Z.I., vol. 57, p. 342, 1926). The internal anterior rib representing the branchial fissure is clearly visible and the spacing of the marginal crenulations suggests a fairly coarse radial sculpture.
There are no other Eocene records of the group in New Zealand.
Monalaria concinna (Suter)
Pahi specimens are not so strongly tuberculate as the holotype and other South Island examples. The nodules on the two lower keels, in particular, are weak, but the finer spiral sculpture and shape of the shells agree so well with concinna that such differences may be infraspecific. There is no doubt as to the affinity with concinna from the type Bortonian rather than to gracilis Fin. and Marw., from the probably older Matau fauna.
Sigapatella n.sp. aff. mapalia Marw.
The record of a Sigapatella at Pahi (Ferrar, 1935, p. 36) was overlooked by Finlay and Marwick (1937, p. 46) in discussing the earliest New Zealand species of the genus. The record puts back the first appearance of Sigapatella in New Zealand from Whaingaroan to Bortonian, but the Pahi shells, which are too fragmentary and worn to describe, are closer to the Duntroonian S. mapalia Marw. than to the Lorne species, S. rertex Marw., which has a more eccentric, “haliotoid” form.
Genus Tatara* nov.
Shell of moderate size, fusiform, with spire less than aperture in height, sculpture of many strong spirals and weaker axials; aperture sinuous, elongate, armed; lip reflected and denticulate; posterior canal present: columella with callus and plaits.
Type: Cymatium pahiensis Marshall and Murdoch (Trans. N.Z. Inst., vol. 53, p. 81, pl. 18. fig. 5, 1921). Eocene, New Zealand.
In view of the wide distribution of Cymatiid genera, it is possible that this group has been named elsewhere, but search through the
[Footnote] * Tatara (Maori) = a conch shell, one of the Cymatiidae.
available literature has not brought to light any description or figure approaching in apertural features the two species here grouped. Columbraria Schumacher, Plesiotriton Fischer, and Semitriton Cossman seem allied to the present genus in general form, simplicity of sculpture, in columellar plication and low varices. The first two genera have a distinctive varicial arrangement, but Semitriton has varices spaced much as in Tatara; however, the genotype of Semitriton (Plesiotriton dennanti Tate, figured by Cossman, Essais de Pal. Comp., vol. 5. pl. 4, fig. 22, and pl. 5, fig. 11) has different coiling, sculpture and aperture from Tatara and does not seem closely related. Finlay's Cymatium revolutum, from the Kakanui Tuffs (Kaiatan, Upper Eocene) was described from a series in which the outer lip is missing, but an adult specimen with complete outer lip here figured (Pl. 22, figs. 8, 9) from the Kakanui Tuffs at Gee's Point, Kakanui, almost certainly a topotype of revolutum, is clearly congeneric with pahiensis. Unlocalized casts from “Oamaru” collected by A. Hamilton show that the thickened dentate lip is developed at varices in young stages. Tatara has a curious resemblance to the Cretaceous genus Columbellina d'Orb., particularly the Neocomian C. subaloysia Peron (Cossman, op. cit., pl. 7, fig. 8).
The known stratigraphic range of Tatara is Bortonian (mid Eocene) to Kaiatan (Upper Eocene).
Tatara pahiensis (Marshall and Murdoch) (Pl. 24, fig. 12)
The unique holotype, now in the Geological Survey collection, is refigured for comparison with T. revolutum (Fin.), from which it differs in its squatter form, wider aperture, fewer labial denticles (about 12 compared with 18), weaker columellar calus, and coarser spiral sculpture.
The complications of Cypraeid taxonomy make it difficult to deal with the two Pahi species without better comparative material than is available. No other Bortonian (mid Eocene) Cypraeids are known from New Zealand, and their occurrence at Pahi may indicate a more temperate facies of the Bortonian than the standard South Island areas.
Cypraea (? Eocypraea) murdochi n.sp. (Text-fig. 1, a, b, c)
1921. Cypraea, sp. Marshall and Murdoch, Trans. N.Z. Inst., vol. 53, p. 81, pl. 18, fig. 6.
In view of the stratigraphic and systematic interest of Eocene Cypraeidae in New Zealand, the better-preserved of the two Pahi forms is named, on the basis of the incomplete specimen described and figured by Marshall and Murdoch. The species is characterized by its strongly curved aperture and lip, posteriorly; its depressed form and unsculptured dorsum; outer lip narrow and acutely incurved in the middle: armed with three strong and two weaker teeth behind, but smooth further forward. The inner lip has six transverse teeth posteriorly, but is elsewhere missing.
Height (of incomplete holotype), 28·5; greatest diameter, 22 mm.
This species is not unlike such Eocene forms as Eocypraea boadicea Schilder (Lower Bracklesham Beds, Cuisian).
Text-fig. 1—(a–c) Cypraea (? Eocypraca) murdochi n.sp. Holotype. Approx. natural size. (d) Cypraea (? Bernayia) sp. Approx. natural size.
Cypraea (? Bernayia) n.sp. (Text-fig. 1, d)
Shell large, pyriform, expanded posteriorly, spire missing from the specimen. Dorsum evenly arched, dorsoventrally compressed, base flattened. Aperture lateral, relatively wide. Outer lip expanded, broad, dentate; labial teeth present along most of lip, but apparently confined to the inside, strongly declivous. Columella sinuous; anterior terminal ridge, strong, slightly oblique, bordering the outlet, terminating a shallow columella sulcus. Columellar teeth present at least in front. Anterior outlet broken, but wide.
Height, 55; breadth, 39; dorsoventral dimension, 27 mm. This is the species listed in Ferrar (1934, p. 36) as “Cypraea sp., 2 in. long.”
Falscicolus n.sp. ef. allani Finlay
The single contorted fragment from Pahi is closer to the allanikaiparaensis-teuriensis line than to other New Zealand Eocene species (altus Marsh, bensoni Allan, solidus Suter). Compared with topotypes of allani (Kekenodon beds, Wharekuri) the Pahi shell has a blunt peripheral keel crossed by stronger axial ribs and a convex shoulder.
Genus Hemipleurotoma Cossman, 1889
Type (by original designation): Pleurotoma archimedis Bellardi (Miocene, Italy).
Shell of moderate size, turreted, whorls with peripheral nodulous carina below middle; shoulder gently concave, steeply sloping: body whorl below periphery rapidly contracting, beak missing. Ornament: peripheral nodules, about 18 per whorl, elongated axially; spiral sculpture of about 20 fine close-set flattened cords between suture and periphery, undulating over the nodules, where very fine interstitials are developed; three ill-defined spiral cords subdivided into fine riblets of nodules below periphery: three strong spirals on body of whorl below, separated by 4–6 fine spiral cords; base with many
spirals, every fifth or sixth stronger than others. Growth lines sloping straight back from suture to the periphery, where there is a welldefined, moderately deep but open sinus, and broadly convex below.
Height, 26 mm. (incomplete); diameter, 18 mm.
The shell cannot be accommodated in any of the New Zealand genera of the Turrinae, and, in the absence of caual and spire, satisfactory placing in extralimital genera is impossible.
Aturia (Brazaturia) n.sp.
1945. Aturia (Brazaturia) mackayi Fleming. Trans. Roy. Soc. N.Z., vol. 74, p. 413.
Further study has confirmed the writer's opinion (Fleming, 1945, p. 414) that Pahi specimens attributed to A. mackayi represent a different species from the holotype. The Pahi Aturia will be described in a further paper on New Zealand Tertiary Cephalopods at present in preparation.
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