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



Professor Hutton, examining " Bulimus gibhosa, Gld. {Physa}'},'^ 

 notices that the edge of the mantle is simple and not reflected over 

 the shell; that the radula has 126 rows, with formula 27-1-27; 

 he goes on to characterize the teeth at length. Bulimus variabilis, 

 Gray (Physa), is also described as being similar in form of radula, 

 rows 112, formula 18-1-18; and the belief is expressed that 

 probably the other species of Physa described from New Zealand 

 will all be found to belong to the same genus\ 



Professor Tate has expressed a belief that the sinistral spiral 

 Pond-Snails of Australia have been incorrectly placed in the genus 

 Physa. He remarks" that in no instance has he found in the species 

 those distinctions which characterize Physa as separate from Bulinus. 

 He observes that the mantle-margin is neither expanded nor dijj,itate, 

 and he catalogues 10 species as Bulinus. 



Tapparone-Canefri describes^ as belonging to Physa, the new 

 section Physastra with the single species Ph. vestita. From his 

 description of the shell, however (form of Limncea, but sinistral, 

 thicker than the common type of Physa ; surface not shining, but 

 covered with a somewhat thick epidermis, which easily comes off 

 when dry), it is plain that he is dealing with a specimen of the group 

 now under investigation. He figures the specimens, but his examina- 

 tion of the animal was unfortunately not successful. 



The following species of this group have been examined *, and the 

 results appended have been arrived at : — 



General Characteristics. 



Radula long, rather broad, consisting of 140-220 rows ; central 

 tooth not equal in size to first lateral, bicuspid ; cusps rather blunt ; 

 laterals and marginals together about 30-40 in number ; laterals 

 7-12, tricuspid ; cusps not much differing in length ; passage to 

 marginals gradual ; marginals serrate, often much curved at extreme 

 edge, where they become very small and less serrate. 



Physa gibbosa, Gld. (figs. 1, 1 a). 



Radula with about 144 rows ; cusps of central tooth very blunt ; 

 laterals 7-8, horizontal. Formula 22-8-1-8-22. 

 Hab. Australia. 



Physa proteus, Sowb. (figs. 2, 2 a). 



Radula with about 83 rows (specimen probably imperfect), very 

 similar to gibbosa. Formula 27-8-1-8-27. 

 Hab. Australia. 



^ Trans. N. Z. Inst. xiv. 1881, p. 155. Btilimus must surely be a misprint 

 for Bulinus, and the foi-mula of B. variabilis is a little suspicious. 



- Trans. Eoy. Soc. S. Austr. v. 1882, p. 51. 



'■ " Fauna Malacologica della Kuova Guinea." Ann. Mus, Stor. Nat. Geneva, 

 xix. 1883. 



* All the specimens have been prepared by and are in the collection of Mr. 

 H. M. Gwatkin, M.A., of St. John's College, Cambridge. 



