PLATE XXIX. 11. Odostomia dolichostoma, Suter. 2.1 mm. by 4.2 mm. 2.4 mm. by 5.6 mm. (Menestho) sabulosa, Suter. 1.8 mm. by 4.2 mm. 17. Eulima truncata, Suter. 1 mm. by 3 mm. 12. Fig. 13. Fig. 14. Fig. 15. Fig. 16. Fig. Fig. Fig. 18. Fig. Fig. Fig. Fig. titahica, Suter. 1-4 mm. by 4 mm. 19. Cuspidaria fairchildi, Suter. 13 mm. by 6 mm. PLATE XXX. 3. Latirus huttoni, Suter. 10.5 mm. by 18 mm. 14 mm. by 26 mm. ART. XXXVI.—Notes on some New Zealand Marine Molluscs. BY TOM IREDALE. [Read before the Philosophical Institute of Canterbury, 6th November, 1907.] Plate XXXI. THESE unconnected notes are presented in their present unfinished state for the sole reason that I will be, myself, unable to further my studies in connection with them in the near future. They relate chiefly to Chitons, limpets, and Acmas, which have been my favourites whilst collecting. Notes referring to other species are here incorporated on account of interest attaching to them. I hope by publishing these fragmentary articles to draw attention to the molluscs noticed, and thereby get the problems propounded solved. I intend further investigating some of the South Island queries, but would like to see those which also relate to the North Island taken up by the conchologists resident in the North Island. Ischnochiton fulvus, Suter. Ischnochiton fulvus, Suter, Journ. Malac., vol. xii, p. 66, 1905. That the Ischnochitons of the South Island of New Zealand have been neglected by collectors this species would apparently prove that this is due to the variation in colour of I. longicymba, Q. and G., is certain. I first met with this species as a red-brown shell dredged in shallow water in Purau Bay, Lyttelton Harbour. I then found a pure-white shell at Sandfly Bay, Otago Peninsula. The small size and constant coloration induced me to separate these shells from I. longicymba, Q. and G. At that time I did not know of the existence of I. fulvus, Suter, and consequently these specimens remained unnamed in my collection. At Shag Point, Otago, and all round the Otago Peninsula this species is abundant. It usually lives on clean smooth stones, unassociated with I. longicymba, Q. and G. When the two occur on the same stone, I. fulvus, Suter, is on the clean edge, whilst I. longicymba, Q. and G., is on the muddy side underneath. I. fulvus, Suter, is as variable as regards colour as almost any other Chiton, but is almost always unicoloured; it runs through all the shades from pure-white through pale-yellow to fulvous and red-brown. The most striking shell, however, is a deep-green, with a green-and-white girdle. I might here point out that very probably two or three species are doing duty in New Zealand collections for I. longicymba, Q. and G. Whilst closely searching for Chiton stangeri, Reeve, I obtained a small-keeled Ischnochiton which I have not again found. I have, however, found another species of Ischnochiton which I have not been able to identify with any Australian species. This is a low-keeled species, with the lateral areas sculptured like I. divergens, Reeve, and a peculiar pattern of coloration. Callochiton platessa (Gould). Callochiton platessa (Gould), Suter, Proc. Mal. Soc., vol. ii, p. 184, 1897. This quotation gives full references, and is the only record of this Australian species in New Zealand. The specimen there referred to is of unknown habitat, and was obtained prior to 1872. The refinding of this species is, therefore, worthy of record. Collecting at Shag Point, Otago, with Mr. W. R. Brook Oliver, he found one specimen, and afterwards I obtained two more. These were obtained from under stones at the bottom of a deep rock-pool. I identified these from specimens from Port Jackson, New South Wales. This makes the third species of Callochiton I have obtained whilst littoral collecting-a curious circumstance when it is remembered that all the previous records of this restricted genus in New Zealand refer to dredged specimens. In the same pool that contained the C. platessa was found a single specimen of a new species of Acanthochites. This species is too well characterized to be the second species of Acanthochites mentioned by Pilsbry (Man. Conch., ser. i, vol. xv, p. 16). Plaxiphora ovata (Hutton). Plaxiphora ovata (Hutton), Suter, Proc. Mal. Soc., vol. ii, p. 191, 1897. References are given in this paper, where Suter writes, "This handsome but rare mollusc is found mostly in roots of D'Urvillea." I have never yet found it on any other station, and, searching for specimens at Sandfly Bay, Otago Peninsula, my friend Mr. W. R. Brook Oliver obtained a lovely specimen with six valves only. In the succeeding note, written previously to this find, the rarity of this find is shown. As this is the first occurrence in New Zealand of such an abnormal specimen, I am giving an illustration of it (Plate XXXI, fig. 1). In this specimen it will be noticed that the last valve is of unusual size for this species, the shape of the last valve in normal specimens being one of the chief characters of the subgenus Fremblya, which includes only one other species, P. egregia, H. Adams, of New South Wales. Chiton pellis-serpentis, Quoy and Gaimard. Chiton pellis-serpentis, Q. and G., Suter, Proc. Mal. Soc., vol. ii, p. 195, 1897. In the paper quoted, Suter gives full references. I have to record the occurrence of a specimen of this species having five valves only, and herewith give an illustration from a photograph (Plate XXXI, fig. 2). This specimen is, as far as I can trace, unique. Pilsbry wrote (Man. Conch., vol. xiv, p. xiii, 1894), “The occurrence of 6- and 7-valved Chitons has been noted as early as the time of Linnæus. It is likely that the 6-valved were artificial fabrications, although a certain number may perhaps be traced to incorrect drawings." Since the publication of Pilsbry's monograph increased interest in the collecting of Chitons has caused undoubted instances to be put on record. In the Proc. Mal. Soc, vol. ii, p. 154, 1897, Bednall records the occurrence of a 6-valved specimen of Plaxiphora conspersa (Ad. and Ang.). Sykes, in his presidential address on "Variation in Recent Mollusca" (Proc. Mal. Soc., vol. vi, p. 268, 1905), mentioned that 6-valved specimens of Trachydermon ruber, Linné, and Ischnochiton conspicuus, Cpr., had recently been noted elsewhere, and that he himself had met with a 3-valved specimen of Ischnochiton contractus, Reeve, which is preserved in the British Museum. Chiton æreus, Reeve. Chiton æreus, Reeve, Suter, Proc. Mal. Soc., vol. ii, p. 195, 1897. Suter's references refer to this species, though his letterpress does not, as has since been pointed out by himself. The following year Suter queried New Zealand as the habitat of this species (Trans. N.Z. Inst., vol. xxxi, p. 63, 1898 [1899]), yet on the east coast of the South Island this species cannot be considered rare. I can get specimens any day I wish in Lyttelton Harbour, and have obtained specimens at every other locality I have visited on Banks Peninsula. It is common at Shag Point, Otago, and all round the Otago Peninsula. The normal colouring of this Chiton is a bluish-green, sometimes with the girdle marked with white. Yellow-green occurs in some localities; pure-lemon-yellow, yellowish-white, purewhite, puce-coloured, and bright-red-brown specimens are also rarely met with. In Otago, however,, shells occur which I call albinos. So far I have obtained five distinct types. The general appearance of the shell is white: first, in which the whole is splashed with greenish-black; then, the valves are pure-white, with the girdle blackish-brown; next, the shell is pure-white with a greenish tinge, the girdle green-and-white; a fourth has the valves speckled with green and suffused with yellow, the girdle green-and-white; lastly, the valves suffused with greenish and the girdle pink. Acmæa rubiginosa (Hutton). Acmaa rubiginosa (Hutton), Suter, Proc. Mal. Soc., vol. vii, p. 315, 1907. Upon shells of Haliotis iris, Martyn, at Lyttelton occur Acmaas. I separated them as lacunosa (= rubiginosa) and cingulata. Upon reading Suter's paper I re-examined my specimens, comparing them with undoubted specimens of A. rubiginosa, Hutton, from the Chathams, with the result that I consider my shells identical. At Shag Point, Otago, I first found dead shells and then live ones on Haliotis iris again. The dead shells are inseparable from the dead shells from the Chathams. Acmæa cantharus (Reeve). Acmaa cantharus (Reeve), Suter, Proc. Mal. Soc., vol. vii, p. 320, 1907. In the paper quoted Suter restricts A. cantharus, Reeve, to New Zealand. As in that paper he does not discuss the relationships of the shells listed in Australia under that name, I here do so. That this is necessary for the understanding of this species is shown by the following: Pritchard and Gatliff (Proc. Roy. Soc., vol. xv (n.s.), p. 195, 1903), in their list of Victorian shells, believed A. cantharus, Reeve, was a Victorian shell, but could not give it specific rank, citing it as a synonym of A. septiformis, Q. and G. I have examined shells sent by Mr. Gatliff in support of this classification, and I quite agree that the shell so classed is a variant of A. septiformis, Q. and G., but it is certainly not the New Zealand shell called A. cantharus, Reeve. Tate and May, in the "Revised Census of the Marine Mollusca of Tasmania" (Proc. Linn. Soc. N.S.W., vol. xxvi, p. 412, 1901), consider A. cantharus, Reeve, as a distinct Tasmanian species. Mr. May sent me shells identified as above, but they are not A. cantharus, Reeve. They may be an extreme form of A. septiformis, Q. and G., but that point must be settled by a study of the shells in their environment. In the Trans. Roy. Soc. S. Aust., vol. xxx, p. 215, 1906 (1907), Dr. Verco identifies a South Australian shell as A. cantharus, Reeve. He treats fully of the shell so named, and has since expressed the opinion that the South Australian shell is identical with the New Zealand shell. The specimens he sent me, though very similar, I do not consider conspecific with ours. They are much eroded, whereas the New Zealand shell is very rarely so; the general coloration, as shown by the literature and these specimens, is the exception among New Zealand shells. I, however, think the South Australian shells worthy of a name, but they should not be called A. cantharus, Reeve. I therefore conclude, as Suter already has done, that A. cantharus, Reeve, does not occur in Australia. Let us now consider the specific rank of A. cantharus, Reeve, in New Zealand. Suter gives it full specific rank, but the study of South Island shells does not warrant this. The characters Suter uses for separating the two I have found to be of very little value. The size of the shells depends a great deal upon their station. A shell living in a secluded cavity, free from the action of rain, may attain a large size, and does not suffer from erosion. In the same locality shells living on boulders exposed to rain are small and much eroded. These exposed shells never attain a large size. I have cantharus much larger than Suter's measurements-viz., 26 by 20 by 9 mm., 25 by 19 by 9 mm., and 24 by 18 by 10 mm. The prominence of the radial striation is an inconstant character, undoubted pileopsis having radial sculpture almost microscopic. As eroded shells occur, this character could only be used in conjunction with others. |