136 REV. A. H. COOKE ON THE [Mar. 19, 



1. On the Generic Position of the so-called Physa of Aus- 

 tralia. By the Rev. A. H. Cooke, M.A., F.Z.S. 



[Eeceived 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 JFreshwater 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 others" ; 

 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 Limncea 

 are known, and only about seven of Planorbis. Professor Tate and 

 Mr. Brazier, in their ' Check-list of the Freshwater Shells of 

 Australia ' ^ enumerate 54 species of Pkysa\ " more than half [the 

 number] for the whole world." 



These Australian PhyscB present, as a group, certain well-marked 

 characteristics. They are, as a rule, remarkably large, tliick shells, 

 sometimes gibbous, sometimes much acuminated, sometimes sur- 

 rounded with sharp ridges or keels. The columellar fold is 

 generally strong, and in many cases there is present a stout epi- 

 dermis. 



It does not appear that the animal of many of these species has 

 been examined in order to see whether they had anything in com- 

 mon 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 New Caledonia" (14 species), Tasmania" (12 species), 

 New Zealand'' (8 species), Tonga Islands" (2 species), Viti Islands'* 

 (2 species). New Guinea^" (3 species). This fact confirms the close 



^ Journ. Linn. Soc, Zool. xvi. 1883, pp. 255-317. 



^ I have noted the following as probable: — proteus, SoMvh., =:pi/ramidata, 

 Sowb., -\-dispar, Sowh., +pecforosa, Conr., +hreviculmen, Sm., -\-badia, Ad. and 

 Ang., -\-concinna. Ad. and Ang., -\-tcxturata, Sowb. : gihhos<a, G\(S..=prodiicta, 

 Sm., -\-hcddomei, N. and T., -{-fusiformis, N. and T. : rcevci, Ad. and Ang., =ca- 

 rinata, H. Ad., -\-obesa, H. Ad., -\-trimoata, H. Ad., +bonus henricus. Ad. and 

 Ang., +cumin(/u, H. Ad. 



^ Proc. Linn. Soc. N. S. Wales, vi. 1882, pp. 552-5G9. 



' Including Tasmanian species. 



' Various papers in the ' Journal de Couehyliologie.' 



" E. M. Johnston, Proc. Eoy. Soc. Tasm. 1878, pp. 19-29. 



' Tenison-Woods, Proc. Linn. Soc. N. S. Wales, iii. 1879, p. 139. 



" Mousson, Journ. de Conch. 3rd ser. xi. 1871, pp. 17, 18. 



^ Mousson, Journ. de Conch. 3rd ser. x. 1870, pp. 130, 131. 



^^ Tapparone-Cauefri, Ann. Mus. Gen. six. 1883 (two species common to Aus- 

 tralia). 



