Art. XXIII.—On the Occurrence of Fredericella sultana in New Zealand.
Communicated by Dr. Chilton.
[Read before the Philosophical Institute of Canterbury, 6th June, 1906.]
The specimen upon which the identification of this New Zealand fresh-water polyzoon with the well - known and widely distributed Fredericella sultana is based was found growing on a dead leaf in a pond in the Acclimatisation Society's Gardens at Christchurch, on the 13th September, 1898. I made a sketch of the fully extended zooid in the living condition, and satisfied myself that the lophophore was not hippocrepian, but that the tentacles (about twenty-two in number) were arranged in the manner figured and described by Allman* for Fredericella sultana. The much-branched tubular cœnœcium is of a pale-
[Footnote] * “Monograph of the Fresh-water Polyzoa,” London, Royal Society, 1856.
brown colour, and incrusted with diatoms. It differs from that figured by Allman for the British form in being more slender, and in the suppression (complete or partial?) of the ridge-like keel—which, however, does not appear to be very prominent even in British specimens.
The only difference which I could detect in the zooid itself was in the form of the epistome, which in the New Zealand specimen was bluntly rounded at the apex, while Allman's figure (pl. ix, fig. 7) shows it as being gradually sharp-pointed. This may be due to difference in the state of contraction, and in any case can hardly be regarded as of specific importance. The specimen contains no statoblasts; and, pending the examination of these in the New Zealand form, the specific identification may be considered as somewhat doubtful.
Fredericella sultana has been recorded from various parts of Europe and from Australia,* while Kræpelin† regards the three American species‡ of Leidy and Hyatt as doubtfully identical with this species.
It is interesting to note that Jullien§ regarded Fredericella sultana as being a monstrous form of Plumatella lucifuga, but Kræpelin does not agree with this view, and maintains the genus.
Hutton, in his “Catalogue of the Marine Mollusca of New Zealand,”∥ records the occurrence of Plumatella aplinii, Mac-gillivray, in the Malvern Hills. As he states that he only examined dried specimens, however, this identification must be regarded as doubtful. Hamilton, in 1879,¶ described a form from near Napier, which he identified (somewhat doubtfully) with Plumatella repens. He examined the living animal and the statoblasts, so that it seems tolerably certain that the genera Plumatella and Fredericella both occur in New Zealand, as they do also in Europe and Australia (Whitelegge). Hamilton has also recorded** the occurrence near Dunedin of Paludicella ehrenbergi; so that we have in New Zealand at least three of the common genera of fresh-water Polyzoa, while none of the species, can, in the present state of our knowledge, be regarded as endemic.
[Footnote] * Whitelegge, Proc. Linn. Soc. N.S.W., viii (1883), pp. 297, 416.
[Footnote] † Kræpelin, “Die Deutschen Suswasser - Bryozoen,” Festchrift des Naturwissenschaftlichen Vereins, Hamburg, 1887.
[Footnote] ‡ F. regina, Leidy (Proc. Acad. Nat. Sci. Philadelphia, vol. v, 1851) F. walkottii and F. pulcherrina, Hyatt (Communications Essex Institute, vols. iv and v, 1865-6).
[Footnote] § Jullien, “Monographie dos Bryozoaires d'Eau douce”: “Bulletin de la Société Zoologique de France,” vol. x, 1885.
[Footnote] ∥ Wellington, 1873, p. 104.
[Footnote] ¶ Trans. and Proc. N.Z. Inst., vol. xii, 1879, p. 302.
[Footnote] ** Trans. N.Z. Inst, vol. xxxv, 1902, p 263.