TESTACEA FROM THE PLEISTOCENE MARL OF MOWBRAY SWAMP. 
the following observations regarding this group* :—‘‘ The sinistral 
spiral pond-snails of Australia have been placed (incorrectly so, I 
believe) in the genus Physa. The thick periostracum of most of 
them, which in many of them is prolonged into cilia or bristles, is 
Ine ompatible with a largely reflexed mantle. I have not examined 
all the Australian so-called Phys, but in no instance have I found 
those distinctions which characterize Physa as separable from 
Bulinus. . . . . . The mantle margin is neither expanded 
nor digitate, in B. tenwistriata, however, it has three small serratures 
on the columella side.” 
In looking into this question of the generic position of our sinistral 
pleistocene fossils the present writer has examined two typical 
ltving Victorian species, namely, Bulinus bullatus, Sow. sp.t, and B. 
crebreciliatus, T. Woods sp.f, with the following results :— 
The edge of the mantle in both these species is slightly reflected 
and undulate (Pl. I., figs. 1-3), but is not divided into numerous 
distinct angular tags, as in Physa (see also Pelseneer$). This 
Australian type of shell would, therefore, naturally fall into the 
genera Bulinus or Aplexa, but that the latter has a polished shell. | 
The relationship was then tested by the structure of the radula. 
Aplexa in being placed with Physa in the Physide gives no evidence 
of relationship with the Australian specimens I have examined. In 
Bulinus proteus, Sow. sp., the radula, on the contrary, shows its 
relationship to be with the Planorbide (PI. I., figs. 4a-c), im which 
family Bulinus is placed by Pelseneer. The centrals and laterals 
of the lingual ribbon in B. proteus are only slightly modified from a 
radula such as Planorbis corneus, Linne{], the three cusps being a 
constant character of the free edges of the teeth**. 
Buxinus Tasmanicus, T. Woods sp. 
(Plate I., Figs. 5, 5a.) 
Physa tasmanica, T. Woods, 1876, Proc. R. Soc., Tas., for 1875, 
p. 74. 
It was of this species that Tenison Woods remarked (op. supra 
cit., p. 74) that it “is the common Physa of the country, and is 
found in all the inland streams. It is, however, so closely allied 
to the Physa fontinalis which is diffused over Great Britain and 
Europe, that we may well doubt if it be distinet?7. If not, has it 
* Trans. R. Soc. 8. Austr., vol. v., 1882, p. 51. 
+ “ Physa bullata,” Sowerby, in Reeve, 1874, Con. Icon., fig. 97. 
t ‘“‘ Physa crebreciliata,’ T. Woods, Proc. R. Soc. Vict., vol. xiv., 1878, p. 63. 
§ Treatise on Zoology, pt. 5, Mollusca, Oxford, 1906, p. 186. 
|| See Fischer, P., Manuel de Conchyliologie, 1887, p. 511. 
{| Op. supra cit., p. 504. 
** Since writing ‘the above, Mr. C. J. Gabriel has kindly drawn my attention to an important 
paper by the Rev. A. H. Cooke (Proc. Zool. Soc., Lond., for 1889, pp- 136-143), ‘‘On the 
Generic Position of the so-called Physe@ of Australia,” in which the structure of the radula is 
fully discussed. The conclusions arrived at are in exact agreement with the above investigations, 
that the Australian Phys@ are really sinistral Limneids. but in their radule nearer to Planorbis 
than to Limnea. 
++ Physa fontinalis is a shorter form with a less acuminate spire. 
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