138 REV. A. H. COOKE ON THE [Mar. 19, 
Professor Hutton, examining “ Bulimus gibbosa, 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 digitate, 
and he catalogues 10 species as Bulinus. 
Tapparone-Canefri describes*, as belongingto Physa, the new 
section Physastra with the single species Ph. vestita. From his 
description of the shell, however (form of Limnea, 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 pened at extreme 
edge, where they become very smail and less serrate. 
Puysa ersposa, Gld. (figs. 1, 1a). 
Radula with about 144 rows; cusps of central tooth very blunt ; 
laterals 7-8, horizontal. Formula 22—8—1—8-22. 
Hab. Australia. 
Paysa 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. 
1 Trans. N. Z. Inst. xiv. 1881, p. 155. Bulimus must surely be a misprint 
for Bulinus, and the formula of B. variabilis is a little suspicious. 
* Trans. Roy. Soc. 8. Austr. v. 1882, p. 51. 
’ «* Mauna Malacologica della Nuova ‘Guinea,” Ann. Mus. Stor. Nat. Genova, 
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. 
