266 Transactions. — Zoology. 



Potamopyrgus spelaeus, Frauenfeld, sp. 

 Hydrobia spelcea, Frauenfeld, Verb-. Zool. Bot. Gesell. Wien, 

 vol. xiii. (1862), p. 1022 ; vol. xv, p. 526, pi. viii. Hydrobia 

 spelcea, v. Martens, Crit. List. N.Z. Moll. (1873), p. 15. By- 

 thinella spelcea, Hutton, Manual N.Z. Moll. (1880), p. 82. 

 This species was found together with P. reevei in moa-bone 

 caves. A translation of the diagnosis is given by Hutton, but 

 the dimensions are not quite those of Frauenfeld ; the type is 

 3 mm. long by l - 6 mm. in breadth. This minute species is nearly 

 allied to pupoides, Hutton, which, however, is mostly, but not 

 always, smaller, and constantly of pupoid form. 



The specimens in my collection I take to be almost typical 

 were collected by Mr. A. Hamilton, now Director of the Colonial 

 Museum, in the salt springs at Te Mahia, Hawke's Bay, and 

 they show the same dimensions as the type specimen. A 

 rather large form comes from the tidal part of the Wanganui 

 River, and its dimensions vary from 3 x If mm. to 3 1 x 2 mm. 

 Very small specimens occur at Nelson, the largest measuring 

 2J x 1J mm., the smallest 2x1 mm. The latter is the usual 

 size of P. pupoides, but the Nelson examples are distinguished 

 by much more convex whorls, deeper suture in consequence, 

 and a more conoidal spire. Forms with ventricose body-whorl 

 were collected by Mr. Chadwick on the upper Wanganui River, 

 and in a cold mineral pool at Rotorua by Lady Frances Brown, 

 a most enthusiastic collector. What I consider to be the same 

 species are examples collected by Mr. Charles Cooper, of Auck- 

 land, in hot-spring water at Te Aroha. These specimens are 

 very variable in shape, some approaching the type and measur- 

 ing 3 x \\ mm., others with a more inflated body-whorl show 

 I mm. greater breadth ; they all have only four whorls. This 

 is the only instance known to me of a mollusc living in hot water 

 in New Zealand, while it is well known that Neritina and Bi- 

 ihynia have been found in France living in water from 68° to 

 122° Fahr. 



Type in the K.K. Hofmuseum, Vienna. 



Potamopyrgus spelaeus, Frfld., subsp. pupoides, Hutton. 

 Potamopyrgus pupoides, Hutton, Trans. N.Z. Inst., vol. xiv. 

 (1882), p. 146, pi. i., figs. D-H. Potamopyrqus pupoides, 

 Hedley and Suter, P.L.S. N.S.W. (2), vol. vii. (1893), p. 620. 

 Potamopyrgus pupoides, Suter, Journ. de Conch., vol. xli. 

 (1893), p. 222. 



I have typical specimens from brackish water in the Heath- 

 cote Estuary, near Christchurchj and they are so nearly allied 

 i o Frauenfeld's spelaeus that I find it advisable to give P. pupoides 

 only subspecific rank. It is distinguished from the species 



