1889.] SO-CALLED PHYSiE OF AUSTRALIA. 13/ 



relationship between these groups of the South Pacific, which is 

 already indicated by the distribution of Rhytida, Janella, and 

 Placostylus. 



The object of this paper is to show that these so-called ' Phijsce' 

 the sole claim of which to the title is that they are sinistral fresh- 

 water-shells, are not Physce at all, but a group of sinistral Limnseidse, 

 characteristic of the geographical area above indicated, and also of 

 another part of the world, where their presence is of extreme interest. 



This view rests primarily upon an examination of the radula of 

 some of the species concerned. 



As is well known, the radulse of the Physidae and the Limnseidse 

 are essentially different, and tend to remove Physa much further 

 away from Limncea than are either Planorhis or Ancylus. Fischer 

 describes them as follows^ : — 



Physidae. Limn^id^. 



Eadula composed of teeth ob- Teeth of the radula in hori- 



liquely arranged ; central tooth zontal rows, bi- or tricuspid [cen- 



multicuspid ; laterals and mar- tral tooth bi- or tricuspid, never 



ginals pectinate or serriform, and multicuspid] ; marginal teeth 



provided with a special narrow serriform'. 

 appendage on the upper and ex- 

 terior edge. 



In the ' Journal of Conchology,' v. 1887, pp. 241-243, 1 described, 

 under the name of Limneea physopsis, a new species of these Aus- 

 tralian ' PhyscB.' The reasons given for believing the species to be 

 Limnaeidan and not Physidan were based on (1) a consideration of 

 the radula, and (2) the general facies of the shell. It was suggested, 

 purely on grounds of general similarity of shell, that two other 

 Australian species of ' Physa' viz. P. hainesii, Tryon { = latilabiata, 

 Sowb.), and P. newcomhi. Ad. and Aug., were also Limnseidse. 



Since that date several other species of this group of * Physa ' 

 have been examined, and with similar results. It may at once be 

 asserted that, in spite of the 52 or .54 species enumerated, Physa has 

 yet to establish its claim to be an inhabitant of Australia. Every 

 species as yet, which has been examined anatomically, turns out not 

 to belong to that genus ; and I am strongly of opinion that further 

 investigation of the animals of the species as yet known only by the 

 shells will afford more evidence of a similar kind. 



The note of suspicion has already been sounded more than once 

 with regard to these Australian Physce. Mr. R. M. Johnston has 

 noticed a " peculiar arrangement " of the lingual teeth in P. tas- 

 manica, the medials of which are 2-cuspid, the laterals 4-, E-, and G- 

 cuspid, the extreme ones having a resemblance to the closed digits 

 of the hand'*. 



^ Manuel de Conchyliologie, pp. 603, 510. 



- It may be remarked that this description is inadequate, $o far as Ancylus 

 proper is concerned. 



^ Proc. Roy. Soc. Tasmania, 1878, pp. 19-29 : he uses the term laterals to 

 include marginals as well. 



