Art. XVI.—Additions to the New Zealand Molluscan Fauna.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 40, 1907, Page 254

Art. XVI.—Additions to the New Zealand Molluscan Fauna. By W. H. Webster, B.A., Waiuku. [Read before the Auckland Institute, 12th December, 1907.] Plates XX and XXI. Acanthochites (Loboplax) mariae, n. sp. Plate XX, figs. 1–11. Shell elongated, elevated, dorsal angle about 110. Colour greenish-grey, minutely freckled with dark. Latero-pleural areas crowded with flattened granules, strap-shaped or oval, as in A. zelandicus, all the valves being bordered with irregular, raised, white, pebble-like granules of the same type as those in A. violaceus, with which this species also agrees in having 5 prominent lobes on the anterior valve, the ribs being of white raised elongated granules, the ribs of all valves similarly marked; another characteristic feature is the presence of three almondshaped white granules just within the posterior edge of each median valve. Dorsal areas wedge-shaped, the edges being serrated, sculptured with cuneiform lyrulæ. The posterior

valve has the tegmentum longer than the breadth, the hooked mucro being slightly post-median; the area behind it is concave, white, composed of oblong granules, bordered on either side by others of longer form, but the same colour. Anterior valve with 5 slits corresponding to the ribs; median valves with 1 slit; posterior with many slits, the denticles being mostly bifid. In the type these denticles are perpendicular, and not visible from above; in other specimens they extend outwards, and may be seen beyond the tegmentum; in such specimens the mucro is not so prominent, the white area narrower, and composed of long granules like those bordering the oblong granules of the type, these latter being altogether absent, as also are the raised white borders of the valves. It may be that these specimens have not attained their full development, as none of them approach the type in size. Interior blue-green, white towards the edges. Girdle grey-green, leathery, a minute pore at each suture, 4 on anterior valve. The dotted lines on figs. 5 and 7 show the limit of the white granular patch. Figs. 6 and 7 represent the posterior valve of a second specimen. Length of dried specimen, 35mm.; width, 18mm. Hab.—Orua Bay, Manukau Harbour; on rocks at low tide. Type in my collection. The type is unique; seven of the less-developed specimens were found. The apparent hybridism is striking, especially as I have never found A. violaceus on the west coast, though a very small form of A. zelandicus is fairly common. Professor Pilsbry remarks (Man., vol. xv, p. 17) that another species of Acanthochites will probably be found. I have not given the dentition, as it is of little value in determining the position of species or genera of the Placophora. Named after my wife, who is an enthusiastic collector. Tornatina oruaensis, n. sp. Plate XX, figs. 12–15. Shell cylindrical, white, of 3 ½ whorls, slightly concave in the crown, above the centre of which projects the smooth protoconch, tilted at an angle of somewhat less than 900. Sculpture: Faint growth-lines, prominent posteriorly, following the curve of the outer lip, the surface scored with fine wavy spiral furrows. Suture deep. Type I: Crown hollow, the tilted apex visible above it. Outer lip longer than the shell, advancing in the centre and rounded anteriorly; columella arcuate, with a thin but distinct labial pad and a very strong fold, which is thickened anteriorly. Type II: Apex subscalar; aperture shorter than the shell; columella with a much slighter fold than the last.

These shells (about 50), obtained by dredging, show many variations of apex between these types; the protoconch is never sunk below the crown, as in Cylichna. In the Manual no similar shell appears. Height, 3 mm.; breadth, 1.25 mm. Hab.—Orua Bay, Manukau Harbour; in 3 fathoms. Types in my collection. Trochus carmesinus, n. sp. Plate XX, figs. 16–18. Shell broadly conical, with 4 ½ slightly triangulate whorls and flattened base. Colour pale-pink, speckled and marbled with bright crimson. Sculpture: The entire shell finely spirally striated, about 21 on body-whorl and the same on base; a smooth band round periphery. Protoconch very small, of 1 ½ whorls. Suture distinct, not deep. Aperture quadrate. Columella very sloping, with a large denticle near its junction with the body. Umbilicus: A pervious funnel, in which the spiral is faintly visible. Animal and operculum unknown. Height: Major diameter, 8 mm.; minor diameter, 6.25 mm. Type in my collection. One beach specimen from Russell has been in my possession for some years. Confirmation has now arrived in the form of two specimens from Cape Palliser, found in shell sand. Trochus oppressus, Hutton, is dark-green in its normal condition, and has a band of sharp radiate wrinkles beneath the sutures, the plain band round the periphery alone being polished. It is possible that this is the shell referred to by Suter (P.M.S., vol. ii, pt. 6, p. 261) as having been reported by T. W. Kirk from Wellington. Thaumatodon iredalia, n. sp. Plate XXI, figs. 19–22. Whorls 4, last descending. Colour horny, irregularly blotched with dark-brown. Protoconch 1 ¼ whorls, striated. Sculpture: Body-whorl with growth-lines, spiral striations, and 13 strong ribs, which slope backwards from the suture, and extend, sloping forwards, into the umbilicus, which is previous, and occupies ¼ of the major diameter. Aperture advancing slightly above. The body has 1 simple lamella within the aperture; it is hardly visible until the shell is revolved so as to see well into the opening (fig. 21). Major diameter, 3.25 mm.; minor diameter, 3 mm.; height, 1.5 mm. Hab.—Two specimens, both dead, but in perfect condition, from Ashley Gorge, Canterbury. (Bush since burnt.) Type to be presented to the Christchurch Museum.

Sent to me by Mr. T. Iredale, a painstaking and enthusiastic conchologist, who seems to be doing good service in the difficult branch comprising our marine minutiæ. I have much pleasure in calling this pretty shell after the discoverer. Thaumatodon mira, n. sp. Plate XXI, fig. 23. Whorls 4, the last descending more than that of Th. tau. Colour horny, banded with chestnut. Protoconch 1 ¼ whorls, finely malleated. Sculpture: Body-whorl with 40 varicosely angled sinuous ribs, also growth-lines and fine spiral striations. Umbilicus pervious, occupying ⅓ of the major diameter. Aperture advancing slightly above. The apex is more deeply sunk than that of Th. tau, the crown being quite hollow. The body has a lamella within the aperture, not easily recognised as bifid in the position in which the shell is drawn (fig. 23), but its character is clearly seen by revolving the shell slightly. In the illustration the lower flange is seen somewhat sideways, the upper flange appearing edgeways above it; the latter is more prominent than the former. A second short lamella is seen on the outer lip near the columella. Some specimens have a callous white patch inside the aperture on the periphery, thus almost linking them with Th. tau, which usually, however, has a third lamella without a white patch. The exterior of the shell bears no resemblance to Th. tau. Major diameter, 3 mm.; minor diameter, 2.75 mm.; height, 1.5 mm. Hab.—Waiuku; not common. Type in my collection. In vol. xxxvii of these Transactions I mentioned that specimens of Th. varicosa found in this neighbourhood had 2 lamellæ in the aperture instead of 1, as recorded by Suter fide Mr. E. A. Smith. A closer examination reveals the division of the body lamella into 2 flanges, which seems to remove this shell from Th. varicosa: it is still further separated by the fact that Pfeiffer describes Th. varicosa as moderately umbilicated and Th. tau as widely so, while my new shell is more widely umbilicated than Th. tau. The latter is one of our commonest shells, and is very variable in the number of ribs; but their character is constant. These shells also vary in height. I have one specimen almost the same height as Charopa egesta, which it greatly resembles in outline. Kellia bifurca, n. sp. Plate XXI, figs. 24–29. Shell somewhat quadrate, pale-grey; at first glance somewhat resembling K. parva in sculpture, but a closer examination

reveals the linear markings, which, though irregular, have one general direction. The concentric growth-lines are very marked, dividing the entire shell into bands, in each of which the sculpture varies somewhat. Prodisoconch and first ⅓ of the shell white, translucent, and devoid of sculpture; it follows that all young shells are likewise colourless when alive and white when dead. Umbones directed forwards, pointed, shining. Hinge: a large posterior resilium, but no visible external ligament, and no lunule; 1 cardinal tooth in each valve, sometimes accompanied by a small point under the umbo in the right valve and a clumsy thickening of the margin in the left valve, as at fig. 29; an anterior and a posterior lateral in each valve; in some specimens a second posterior in each valve. Pallial line entire. The shell is characterized by two clumsy internal patches of varying shape in different specimens, extending downwards and outwards from behind the hinge; in young shells these are milky, and may be seen through the shell, reminding one of the description of Thyasira albigena, Hedley; in mature shells these patches spread and thicken clumsily in such a manner as to seriously diminish the capacity of the shell. Height, 3.25 mm.; breadth, 4 mm.; depth from valve to valve, 2 mm. Hab.—Orua Bay, Manukau Harbour; plentiful in 3 fathoms. Type in my collection. Rissoina coulthardi, n. sp. Plate XXI, figs. 30–32. Shell imperforate, milk-white, loosely coiled, especially the last whorl, the aperture and its posterior callosity occupying exactly one-half the entire length of the shell. Protoconch minute, shining, colourless. Whorls 5, somewhat flat, extremely glossy, the body-whorl with a few longitudinal markings of pale-brown; in some specimens these stripes are transparent. Suture shallow. Base of one specimen (not the type) with 4 spiral lines. Aperture pear-shaped; a heavy callous at the juncture with the body, and a partly concealed arch in the angle. Columella nearly upright, with a wrinkled twist on the outside of the pillar. Animal and operculum unknown. Height, 3 mm.; width, 1 ½ mm. Hab.—Orua Bay, Manukau Harbour; fifty specimens in 3 fathoms. Type in my collection. Mr. Suter, who has seen this shell, says that it resembles his R. parvilirata. Named after the well-known family of Coulthard, in Orua Bay, a member of which kindly assisted me in my dredging.

Explanation of Plates XX and XXI. Plate XX. Figs. 1–4. Acanthochites mariae, n. sp.; valves 1, 2, 4, 8. Fig. 5. " valve 8, profile. Figs. 6, 7. " valve 8, another specimen. Figs. 9–11. " interior of valves 1, 4, 8. Figs. 12–14. Tornatina oruaensis, n. sp. Fig. 15. " another specimen. Figs. 16–18. Trochus carmesinus, n. sp. Plate XXI. Figs. 19–22. Thaumatodon iredalia, n. sp. Fig. 23. " mira, n. sp. Figs. 24, 25. Kellia bifurca, n. sp.; right valve. Figs. 26, 27. " left valve. Fig. 28. " sculpture. Fig. 29. " hinge of another specimen. Figs. 30–32. Rissoina coulthardi, n. sp.