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Three New Tertiary Gastropods.
[Read before Wellington Philosophical Society, 13th August, 1930; received by Editor, 7th August, 1930; issued separately, 30th September. 1931.]
Of the three new gastropods described below, two from Callaghan's, Greymouth, were discovered in the Victoria College Collection, and were probably collected by the late Mr. P. G. Morgan during his study of the Greymouth Subdivision. The remaining species from Hurupi Creek, Palliser Bay, was sent to the writer in a large collection of fossils from that locality for which he is indebted to Mr. Colin Campbell, after whom the new species is named. The writer's thanks are also tendered to Mr. W. H. A. Penseler for the care he took in photographing the specimens.
Bolma colini, n. sp. Figs. 1–3.
Shell large, turbinate, solid, imperforate. Protoconch broken in the type specimens. Whorls four, angulate, with a gently sloping shoulder surmounted by strong tubercles. Sculpture consisting of strong tubercles on the shoulder angle, 9 to 11 on the spire-whorls, 8 on the body-whorl. Below the suture is a row of oblique, strong rounded tubercles, becoming weaker and finally dying out on the body-whorl. Between this and the shoulder-angle are two weak nodular cords, the nodules on later whorls becoming detached and finally obsolete. On the side of the spire-whorls are two weakly nodular spiral cords, the lower one much the stronger. A third weak spiral appears from the suture on the body-whorl. Following the line of suture on the body-whorl is a line of strong rounded tubercles forming a well defined keel. On the base are eight irregular nodular cords. The inner margin of the base bounding the aperture has three very strong round tuberculate knobs. The surface is covered with fine spiral threads crossed by well-marked, regular growth-ridges. Aperture circular, interior nacreous. Outer lip probably sharp. Columella concave, with a shallow groove developing towards its anterior end. Inner lip spreading well over the umbilical area.
Locality.—Hurupi Creek, Palliser Bay.
Height, 80 mm.; diameter, 84 mm.
Holotype presented to the Collection of the New Zealand Geological Survey.
This species is a close relative of Turbo superbus Zittel, but it has additional spirals, and the tubercles on the sides and shoulderangle are not so strongly marked. There are also three very strong tubercles on the basal margin of the aperture.
Bolma was proposed by Risso in 1826, with Turbo rugosus Linné as monotype. Chenu, Manuel de Conchyliologie, Vol. 1, p. 351, figured this and also Turbo gibberosus Gmelin. Unfortunately, his figures are reversed, as shown by specimens of T. rugosus in the collection of the New Zealand Geological Survey, and the figures of Cossmann and Zittel. T. gibberosus in any case seems to have lapsed into synonymy or have been originally a nomen nudum. The New
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Figs. 1 and 2.—Bolma colini n. sp. Holotype.
Fig. 3.—Bolma colini n. sp. Paratype.
Figs. 4 and 5.—Pachymelon callaghani n. sp. Holotype.
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Figs. 6 and 7—Alcithoe gravicostata n. sp Holotype
Figs. 8 and 9.—Alcithoe gravicostata n. sp. Paratype.
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Zealand shell may prove to be generically separable from true Bolma, but until specimens showing protoconch and complete aperture are available it is left in the European genus.
Pachymelon callaghani, n. sp. Figs. 4, 5.
Shell of moderate size, thick, fusiform. Spire about two-thirds the height of the aperture. Post-embryonic whorls 5, slightly convex with a lightly developed shoulder; body-whorl somewhat inflated. Sculpture of axial ribs, with about equal concave interspaces, 14 on the pen ultimate whorl, but quickly becoming obsolete on the body-whorl. Fasciole concave, plainly marked but not sharply defined from the base of the body-whorl. Aperture narrow, lightly channelled above, and slightly sinused below. Outer lip convex, thick, somewhat reflexed. Columella with three strong plaits and one weaker anterior plait. Inner lip thick, with a sharply defined arcuate outer edge, spreading well across the body-whorl.
Height, 60 mm.; diameter, 26 mm.
Locality.—Callaghan's, Stafford Town, Greymouth.
Holotype presented to the Collection of the New Zealand Geological Survey.
This species resembles P. renwicki Marwick, from the Chathams, but differs in the more convex spire-whorls and the better developed shoulder.
Since the above description was written, twelve specimens very closely resembling the type were obtained from the cliffs east of Lake Ferry, Wairarapa. They were all rather frailer shells, and exhibited a somewhat lower spire and slightly deeper anterior notch than the type.
Alcithoe gravicostata, n. sp. Figs. 6–9.
Shell of medium size, thick, strong. Spire turreted, slightly shorter than the aperture; spire-whorls with a sloping, strongly angled shoulder. Sculpture of heavy axial ribs, with about equal concave interspaces, persisting on the body-whorl to the last quarter turn and running into a well-marked fasciole. Aperture narrow, channelled above, with a strong anterior sinus. Outer lip convex, reflexed. Columella with four primary and three secondary plaits, differing on paratypes. Inner lip spreading thinly over the ribs above, thick below.
Height, 70 mm.; diameter, 27 mm.
Locality.—Callaghan's, Stafford Town, Greymouth.
Holotype presented to the Collection of the New Zealand Geological Survey.
The number of ribs varies on different specimens. Holotype: 13 on the penultimate whorl, 16 on the body-whorl; paratype: 16 and 16. Resembles most A. gatesi Marwick, from which it differs in the larger size and heavier build, and also in the angle on the shoulder and the number of plaits on the columella. From A. haweraensis Marwick, it may be distinguished by the relatively higher spire, slightly less concave shoulder, different shape of the body, and the smaller aperture.