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Show 136 REV. A. H. COOKE ON T H E [Mar. 19, 1. O n the Generic Position of the so-called Physa? of Australia. By the Rev. A. H . C O O K E , M.A., F.Z.S. [Received February 25, 1889.] The freshwater Mollusca of Australia, regarded as a whole, present only one feature which can be considered at all remarkable, namely the extraordinary development of the genus Physa. In a valuable paper " On the Freshwater Shells of Australia " \ Mr. E. A. Smith enumerates no less than 52 species of this genus. It is true he admits that some of these are undoubtedly synonymous with others2; but even if we were bold enough to reduce the number by half, 26 would still remain a large proportion. This is especially evident when we recollect that only eight or nine species of Australian Limneea are known, and only about seven of Planorbis. Professor Tate and Mr. Brazier, in their ' Check-list of the Freshwater Shells of Australia '3, enumerate 54 species of Physa4; " more than half [the number] for the whole world." These Australian Physee present, as a group, certain well-marked characteristics. They are, as a rule, remarkably large, thick shells, sometimes gibbous, sometimes much acuminated, sometimes surrounded with sharp ridges or keels. The columellar fold is generally strong, and in many cases there is present a stout epidermis. It does not appear that the animal of many of these species has been examined in order to see whether they had anything in common with Physa besides the possession of a sinistral shell. One would have thought that the presence or absence of the tongued mantle, reflected over the shell, would have been noticed whenever the animal had been examined. This group of Physa is not peculiar to Australia, though it finds its most extensive development there. Shells of exactly the same facies occur in N e w Caledonia5 (14 species), Tasmania6 (12 species), New Zealand7 (8 species), Tonga Islands8 (2 species), Viti Islands9 (2 species), N e w Guinea10 (3 species). This fact confirms the close 1 Journ. Linn. Soc, Zool. xvi. 1883, pp. 255-317. 2 I have noted the following as probable:-proteus, Sowb., =pyramidata, Sowb., +dispar, Sowb., -\-pcctorosa, Conr., +breviculmcn, Sm., -\-badia, Ad. and Ang., -{-concinna, Ad. and Ang., -\-texturata, Sowb.: gibbosa, Gld.=producta, Sm., -\-beddomei, N. and T., -{-fusiformis, N. and T.: reevei, Ad. and Ang.,=ca-rinata, H. Ad., +obesa, H. Ad., -\-truncata, H. Ad., +bonus henricus, Ad. and Ang., -{-cumingii, H. Ad. 8 Proc. Linn. Soc. N. S. Wales, vi. 1882, pp. 552-569. 4 Including Tasmanian species. 6 Various papers in the ' Journal de Conchyliologie.' 0 R. M . Johnston, Proc. Roy. Soc. Tasm. 1878, pp. 19-29. 7 Tenison-Woods, Proc. Linn. Soc. N. S. Wales, iii. 1879, p. 139. 8 Mousson, Journ. de Conch. 3rd ser. xi. 1871, pp. 17, 18. 9 Mousson, Journ. de Conch. 3rd ser. x. 1870, pp. 130,131. 10 Tapparone-Canefri, Ann. Mus. Gen. xix. 1883 (two species common to Australia). |
