Art. XXV.—Some New Fossil Species of Mollusca.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 51, 1919, Page 253

Art. XXV.—Some New Fossil Species of Mollusca. By P. Marshall, M.A., D.Sc., F.G.S., and R. Murdoch. [Read before the Wanganui Philosophical Society, 20th December, 1918; received by Editor, 31st December, 1918; issued separately, 16th July, 1919.] Plates XIX-XXI. The species of fossil Mollusca which are described in the following pages have been collected from Tertiary beds in several different localities. Some of the specimens were submitted to the late Mr. Suter, but he had no time to describe them. The following species were found at Wharekuri, on the Waitaki River, a few miles above Kurow: Fusinus maorium, Leucosyrinx subaltus, and Crassatellites subobesus. The material from which they were taken is argillaceous greensand, which in this locality rests upon quartz sands, which contain coal-seams. Altogether seventy-five species of Mollusca have been found in these beds, and 24 per cent. of these are Recent species. We regard this bed as a stratigraphical series in the Oamaru system, lying below the Ototara limestone. Ficus imperfectus was found at Target Gully, as well as Venericardia bollonsi Suter and Drillia laevis (Hutton), two species which have not previously been recorded from that locality. These species raise the total number collected at Target Gully to 223. Some 34 per cent. of these are Recent. The horizon is 40 ft. above that of the Ototara stone. It has been placed by Marshall in the Awamoa series of the Oamaru system. Lima waipipiensis was found at the Waipipi Beach, five miles from Waverley. The horizon is probably some 1,500-2,500 ft. below the highest

part of the Castlecliff beds at Wanganui. Such well-known fossil species as Lutraria solida, Cardium spatiosum, Ostrea ingens, and Pecten triphooki have been found in the same bed. In a collection which is quite incomplete some 70 per cent. of the species are Recent. I propose to call this bed, from which more complete collections will shortly be made, the Waipipi series, in the upper part of the Oamaru system. Lucinida levifoliata occurs in the same bed, and also at Nukumaru, where it is associated with Melina zealandica, Lutraria solida, and Struthiolaria frazeri. The whole molluscan fauna so far collected at Nukumaru contains about 80 per cent. of Recent species. This horizon also offers good material for collecting, and will be called the Nukumaru series of the upper part of the Oamaru system. The series is perhaps 500 ft. above the Waipipi series. The two remaining species, Thracia vegrandis and Surcula castlecliffensis, came from the Castlecliff Beach, near Wanganui. The percentage of Recent species in this fauna approximates to 90. It is the highest described series of the Wanganui system. A list of the Mollusca found in it will shortly be published. Ataxocerithium perplexum n. sp. (Plate XX, figs. 5, 6.) Material, two examples, much rolled and having the sculpture almost erased except on a small area near to the aperture, which is spirally ribbed; interspaces and ribs about equal, the latter cut into small gemmules by the varying development of the growth-striae. Shell elongated, turreted, body-whorl exceeding one-third of the total length, base rounded and with an ill-defined spiral ridge, anterior to which it is rather more abruptly contracted. Sutures well marked, apparently not channelled. Apex imperfect. Aperture ovate, produced in a very short open canal; outer lip more or less channelled above; body-wall with a well-marked callus which unites with the columella and forms a distinct ridge; the columella is slightly arched and twisted to the left at the anterior end Length, 34 mm.; breadth, 11 mm.; length of aperture with canal, 10 mm. Locality, Nukumaru, in blue sandy clay. Collector, P Marshall. Type to be presented to the Wanganui Museum. The examples are much worn, the only area with sculpture being near to the outer lip. Sculpture on approaching the aperture in many genera is more or less suppressed; we may therefore reasonably expect a bolder sculpture on the spire-whorls of better-preserved examples. Fusinus maorium n. sp. (Plate XXI, figs. 1, 2.) Material, two fragments; the larger consists of the penultimate and body whorls, with a small part of the canal; the other, the complete canal and greater part of body-whorl. Shell fairly large, fusiform, penultimate whorl subangular at the periphery, body-whorl rounded or slightly angular, rather abruptly contracted at the base; longitudinally and spirally ribbed; canal long, slender, and almost straight; sutures deeply impressed, slightly undulating, margined above and below by a small riblet. The longitudinal ribs are broad and flexuous, about fourteen on a whorl, most prominent on the periphery, obsolete on the lower portion of the base as it unites with the canal; interspaces narrower than the ribs, crossed by undulating spiral cords. On the penultimate whorl there are seven of these, excluding the

small marginals at the sutures; they are widely spaced, much narrower than the interspaces, strengthening on the periphery and forming angular nodules; on the body-whorl there are ten or eleven spirals similar to the whorl above except that the basal are less nodular, thence more closely spaced, smaller and approximating the spirals on the canal, of which there are eighteen or more; in addition there are in the interspaces a few minute spiral lineations. Strong, irregular growth-lines cut the spirals and nodules into minute secondary sculpture. Aperture ovate, narrowed into a long canal; outer lip sharp, slightly crenulated by the sculpture; inner lip with a narrow callus continuous with the margin of the canal. Dimensions (largest fragment): Length, 38 mm.; breadth, 24 mm.; aperture, greatest length (excluding canal), 18 mm. The smaller example has a length of aperture and canal of 30 mm.; breadth of body-whorl, 19 mm. The largest fragment is somewhat compressed and distorted. Locality, Wharekuri, in brown sand. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The species is perhaps nearest to F. solidus Suter, recorded from South Canterbury and North Otago. Ficus imperfectus n. sp. (Plate XXI, fig. 4.) The material comprises a single example only, of which a considerable portion of the outer lip is broken away, also some small part of the columella. The example gives the impression that it is not adult. Shell small, fragile, pyriform, spire slightly elevated, last whorl rounded, the area between the suture and a line with the outer lip very slightly convex, and giving it a slightly shouldered appearance; canal fairly long, anteriorly somewhat curved and twisted to the left. Whorls about four, those of the spire sloping-convex; protoconch small, slightly rounded; the first two volutions smooth, thence minute irregular growth-striae, followed by delicate but well-marked transverse riblets, which as the whorl progresses assume a slightly backward slope; fine spiral threadlets make their appearance. The shell is slightly rubbed, and it is quite probable that the sculpture may extend to all the whorls. On the last whorl the sculpture is more strongly developed, the longitudinals somewhat irregularly disposed, narrower than the interspaces, slightly flexuous on the shoulder, and becoming obsolete on the canal; a secondary sculpture of minute threadlets adorns both riblets and interspaces; spirals on the area between suture and shoulder minute, on the shoulder and anteriorly strengthening and forming small nodules on the axial sculpture, the interspaces wider than the cords and with one or more minute threadlets; on the canal the spirals smaller and more closely spaced. Sutures narrow and slightly impressed. Columella smooth, slightly curved, and thinly calloused. Aperture imperfect. Length, 10 mm.; breadth, 5.5 mm. Locality, Target Gully. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The species is perhaps nearest to F. parvus Suter, from which it may be distinguished by the axial riblets and the small but well-marked nodules on the last whorl. Surcula castlecliffensis n. sp. (Plate XXI, fig. 3.) Shell small, fusiform, spire turreted, aperture and canal about equal to half the total length. Whorls seven; protoconch about one and a half volutions, smooth and with an angular ridge; succeeding whorls strongly

angled slightly below the middle; the angle or keel with oblique longitudinal short nodular ribs, directed backwards, about eighteen on the penultimate whorl; as the whorls progress there are one, two, and three fine undulating spiral grooves which cut the axial ribs into fine gemmules; the shoulder slightly concave, with two or three fine spiral lines; below the angle straight or slightly concave, and with two ill-defined low spirals on the penultimate whorl. Body-whorl below the angular shoulder slightly contracted, more pronounced on approaching the canal; the latter long, tapering, and somewhat twisted to the left; below the nodular area there are three or four rather widely spaced small grooves and a number of very minute threadlets on the canal. Sutures well margined above by a small rounded riblet; aperture ovate narrowed below into a fairly long open canal; columella and inner lip with a thin callus; outer lip with a fairly deep rounded sinus situate between the angle and suture, its position on the lower whorls marked by the growth-lines. Length, 12 mm.; breadth, 4.5 mm. Locality, Castlecliff, in blue sandy clay. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The species is perhaps nearest to S. obliquecostata Suter, from which it may be distinguished by the position of the sutural rib. Leucosyrinx subaltus n. sp. (Plate XX, fig. 7.) Shell elongate-fusiform; spire-whorls with a strong acute keel a little below the middle, absent on the protoconch; the apical whorl is lost, but the adjoining portion is smooth and rounded; body-whorl strongly and sharply keeled, a second low blunt angulation below it, the area between them slightly concave; the spire-whorls above the keel sloping and slightly concave, below sharply contracted and somewhat concave. Sculpture (except the protoconch): All whorls with closely spaced small spiral riblets, which the irregular growth-striae cut into minute gemmules. Whorls about eight, regularly increasing, the last (with the canal) exceeds the spire in length. Sutures linear. Aperture: The outer lip imperfect, certainly strongly angular above, contracted anteriorly, and terminates in a fairly long canal; columella nearly straight. Sinus between the keel and suture not well marked. Length, 30 mm.; breadth, 11 mm. Locality, Wharekuri. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The species is perhaps nearest to L. alta (Harris) var. transenna Suter, from which it may be distinguished by the uniform spiral sculpture on all whorls except the protoconch, and by its more robust form. Lima waipipiensis n. sp. (Plate XIX, fig. 1.) Shell large, irregularly ovate, inequilateral, sculptured with fourteen strong radiating ribs, narrower than the interspaces; these are crossed by irregularly developed growth-striae, which form frequent but irregularly disposed hollow scales on the ribs. Beak curved forward, “imperfect.” Ears—anterior very small, irregularly ribbed; posterior larger, obtusely angular, sculptured with a few small riblets and numerous growth-striae. The anterior end short, the margin descending abruptly and distinctly concave in the dorsal third, thence straight, inclining outwards until coalescing in the basal curve; submargin straight and forming a slight angle on meeting the lower curve of the valve; the submarginal area bent

inwards, long, narrow, and concave above, sculptured with rough irregular lines of growth; the posterior margin forms a broad uniform curve from the ear to the centre of base, thence the curve gradually becomes steeper. Interior with shallow radiating grooves corresponding with the external ribs; adductor impression large, indistinct; hinge broken; margin of the valve sharp and undulating. Dimensions (right valve): Height, 76 mm.; length, 60 mm.; diameter, 13 mm. Locality, Waipipi, in a fine bluish-grey sand. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The description is derived from a right valve. The species belongs to the L. lima group, and may be distinguished from other of our fossil forms by being shorter comparative to its height, and by the fewer and more distinct ribs. Crassatellites subobesus n. sp. (Plate XIX, figs. 2, 3.) Shell elongately ovate, inequilateral; anterior area short and convex; posterior attenuated, the end obliquely truncated; continuous with the curve of the umbo, and extending to the lower margin of the truncation is a broadly rounded ridge, the area above being flattened or slightly concave towards the posterior end, giving the dorsal area a winged appearance. Beaks less than one-third from the anterior end, incurved, and directed forward. Lunule deeply impressed, oval; escutcheon long, narrow, and concave. Sculpture consists of small, rounded, concentric riblets, rather less than two per millimetre, and about the same width as the interspaces, on the posterior dorsal area irregular, mostly coarse striations; towards the base the ribs are more or less irregularly developed and spaced, with a number of growth-striae in the interspaces. Marginal contour: The anterior end from the beak steeply declining, straight, thence broadly rounded; the base a wide sweeping curve, becoming flattened as it approaches the posterior end; posterior dorsal margin sloping downwards, straight or slightly concave, the end obliquely truncated. Interior of left valve-margin smooth; adductor impressions and pallial lines impressed. Hinge with three diverging cardinals, united above, the posterior slender, the lower limbs of the two anterior narrowly separate; posterior lateral forms a long rounded rib with a deep groove above; anterior area a broad shallow groove, above which is a stout rib ending abruptly at the anterior end of the umbonal margin. Dimensions: Height, 32 mm.; length, 54 mm.; diameter of perfect specimen, 20 mm. Locality, Wharekuri. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The species is perhaps nearest to C. obesus (A. Adams) = trailli Hutton; the latter is distinctly triangular, and has a less winged appearance posterio-dorsally. The material consists of one perfect specimen and a left valve; the former is filled with matrix, and it appears too risky to attempt to separate the valves. Lucinida levifoliata n. sp. (Plate XX, figs. 1, 2, 3, 4.) Shell orbicular, subglobose, nearly equilateral, juvenile examples more lenticular; beaks contiguous, directed forward, sharply incurved, and terminating

in a small point; the lunule deeply impressed, ovate. Sculpture consists of irregularly spaced, small, sharp concentric lamellations with fine growth-striae in the interspaces, the lamellae as a rule become more irregular as the base is approached, usually crowded in places marking periods of rest; radiate sculpture is very minute, almost absent in some examples. On the posterior area of the shell is a feeble radiating flexure; the anterior dorsal area is defined by a distinct flexure, excavate above, and the margin expanded. Marginal contour: The posterior dorsal margin declining, slightly curved, distinctly angular on meeting the broad almost uniform curve which extends around the base and terminates at the anterior flexure; anterior dorsal margin immediately in front of the umbo distinctly concave, thence a well-marked rounded projection followed by a shallow concavity. Interior of valves with distinct radiations; anterior adductorscar elongated; the posterior irregularly ovate. Hinge: Right valve with two cardinals, the posterior strongest, usually bifid and a distinct pit on either side; anterior lateral, a stout rib with a small tubercule towards the end; posterior lateral simple: left valve with two diverging cardinals, the anterior usually bifid; anterior lateral distant, the posterior long and well developed. Dimensions: Height, 20 mm.; length, 22 mm.; diameter, 13 mm. Locality, Nukumaru, in blue sandy clay (type); also Waipipi, near Waverley. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The Waipipi example is imperfect: its dimensions (approximate)—height, 24 mm.; length, 25 mm. A smaller but perfect example from Nukumaru is chosen as type. Thracia vegrandis n. sp. (Plate XXI, figs. 5, 6, 7.) Shell small, fragile, oblong, inequilateral, equivalve, truncated posteriorly. Beaks within the posterior third slightly curving backwards, not prominent. A blunt angular ridge extends from the beak to the basal margin of the truncation; in some examples there is a very small ridge which unites with the dorsal margin of the truncation, the area thus defined is flattened and somewhat excavate. Contour: Anterior dorsal margin long with a slightly downward slope, almost straight, the end rounded, the curve rather narrower above; base slightly curved, almost straight, posterior dorsal margin short, slightly excavate below the beak, declining more rapidly than the anterior margin; the end truncated and slightly oblique. Sculpture consists of very fine concentric growth-striae, with usually a few feebly marked restperiods. The valves are slightly rubbed, and there is no indication of radiate sculpture. Interior margins smooth, adductor-scars and pallial line indistinct, the anterior scar the smaller, the pallial sinus apparently not large. Hinge without teeth, deeply cleft under the apex, a comparatively strong oblique and inward-projecting lithodesma posterior to the beak. Dimensions: Height, 8 mm.; length, 14 mm.; diameter (single valve), 2.5 mm. Locality, Castlecliff, blue sandy clay. Collector, P. Marshall. Type to be presented to the Wanganui Museum. The material consists of several valves. It is distinguished from T. vitrea (Hutton) by its smaller size, more oblong form, the truncation comparatively broader, and the less curved basal margin.

Fig. 1.—Lima waipipiensis n. sp. Natural size. Figs. 2, 3.—Crassatellites subobesus n. sp. Natural size.

Figs. 1, 2, 3, 4.—Lucinida levifoliata n. sp. × 1½. Figs. 5, 6.—Ataxocerithium perplexum n. sp. × 1½. Fig. 7.—Leucosyrinx subaltus n. sp. × 1½.

Figs. 1, 2.—Fusinus maorium n. sp. × 1½ Fig. 3.—Surcula castlecliffensis n. sp. × 2½. Fig. 4.—Ficus imperfectus n. sp. × 2½. Figs. 5, 6, 7.—Thracia vegrandis n. sp. × 2½.