68 



tTlati eighty miles apai*!, and separated by an arm of the sea. 

 In Lake Dulvertou is found P. mamillata, which is also found 

 in Bruni Island. I may here remark that a variety oi the latter 

 exactly corresponding with Sowerby's P. attenuata is found in 

 the same lake, and though described as coming from Aus- 

 tralia, Mr. W. Legrand assures me it came from Lake Dul- 

 verton, as it was sent to Mr. Sowerby from Tasmania by Mr. 

 Legrand. Under these circumstances, the species and name 

 should be suppressed, but the matter is one for Australian 

 naturalists. The common Physa of Tasmania I have named 

 P. tasmanica. It Varies very much according to the place in 

 which it is found, and is closely allied to P.fontinalis of 

 Europe. The number of Physas (12) for such a small island 

 is very large, and it may be that some of the species will yet 

 need reduction, yet it must be remembered that Tasmania is 

 an extremely mountainous country. The ridges acting as 

 complete barriers between different parts of the island. 



The genus Bythinia contains species which may possibly need 

 further reduction. Some authors have referred those species, 

 of which the Tasmanian creeks, etc., are so full, to the genus 

 Paludestrina. Under the head of that genus I have given 

 my reasons for classing them as I have done. The partly 

 calcareous operculum appears to me, in the absence of the 

 animal, decisive of the point. Two species of Paludestrina 

 have been described by Mr. Brazier as from Tasmania in the 

 Zoological Society's proceedings, but I have never been able 

 to find any collector who has seen them. I therefore con- 

 clude there is some mistake in the habitat. Nevertheless I 

 have included them in the list, hoping that future investiga* 

 tions may throw some light on the point. 



The four species of Limnea do not call for any remark 

 except that they are local and very distinct from any European 

 or Australian congeners. 



The two species of Ancylus are very remarkable, in fact, 

 Tasmania can boast of the largest and finest species of Ancylus 

 known, being so distinct from every other species, that at 

 one time it was proposed to erect a separate genus for its 

 reception. The other species in no way resembles it, being 

 small and inconspicuous. 



The other genera have nothing peculiar about them. They 

 are the representatives of European species in our streams. 

 It is said that our Pomiatopsis is found in Australia, but as 

 there it is claimed as a Blanfordia, the indentification is 

 doubtful. 



It is remarkable that there is only one Unio in Tasmania, 

 and that is entirely restricted to rivers emptying themselves 

 on the north side of the island. 



