86 PETTERD : ON FRESHWATER SHELLS OF TASMANIA. 



Bithynia tuiica7dnata^ Tennison Woods. Pro. Roj^al 

 Soc. Tas., August, 1875. 



Habitat — Generally distributed throughout the Island. 

 A very variable shell in colour, size and form, hence the 

 number of species that have been formed. Specimens of 

 all intermediate grades are commonly met with, running so 

 imperceptibly into each other that it is impossible to separate 

 them with anything like satisfaction. I have never met with 

 a shell in which extreme individuals show so much variation. 

 It is generally coated with confervoid growth. 



29. Bithynia Dunrobinensis, Tennison Woods, Pro. Royal 

 Soc. Tas., August, 1875. 



Habitat — River Ouse. Longer and more slender than 

 its congeners. 



30. Bithynia Huonensis, Tennison Woods. Pro. Royal Soc, 

 August, 1875. 



Habitat — Huon River, Sorrel, George Town ; also Mel- 

 bourne, Victoria. A very different form to any of the other 

 species of the genus; in fact, it is so distinct that I think it 

 requisite to form a genus for its reception. It is of a pyramidal 

 form with an elevated, acuminate spire of a shining, rich brown 

 color. 



31. Bithynia Dyeriana, n. sp. 



Shell minute, turbinately conical, brown, much corroded, 

 spire very obtuse, whorls 43^, rounded, somewhat inflated ; 

 suture impressed; aperture ovate ; margins continuous. 



Habitat — Stream Long Bay (Mr. B. Dyer). The smallest 

 of our species, apparently confined to the locality given when 

 it was got by my friend Mr. Dyer, after whom I have much 

 pleasure in naming it. 



32. Annnicola? Launcestonensis, Johnston. Pro. Royal Soc. 

 Tas., 1878. 



j.C, ii., Alaf.; 1870 



