76 



Habitat, Upper Huon Elver. A very distinct fusiform 

 species much larger and more solid than P. huonensis. 



BYTHINIA. Gray. 1821. 



Testa Uirhinato-conica siih^imhiUcata,fidvo-virida,pellucida, Icevigata 

 anfractibus 5-7, 2^lus minusve rotunddtis, epidermide obscure corned 

 indutis ; apertura pyriforme-ovdta, integrd. 



Shell turbinately conical, subumbilicate, fulvous i^reen, pel- 

 lucid, smooth ; whorls 5 to 7, more or less rounded ; clothed 

 with an obscurely horuy epidermis, aperture pyriformly ovate, 

 entire. 



It has been generally believed that no Bythinia exists in 

 Australia and Tasmania, and the shells here described have 

 been classed by some naturalists as Paludestrina, D'Orbigny. 

 This genus was, however, erected for semi-globose solid thick 

 shells with a short obtuse spire, and a callous columella, with 

 which description none of the following would agree. But 

 they do agree with Gray's genus of Bythinia, especially in 

 this that the operculum is partly horny and partly, as far as 

 I have been able to ascertain, calcareous. This feature should, it 

 seems, enhance the importance of the other details in assigning 

 a true position to the shells. It is a fact, however, that we 

 have in the freshwater streams of Tasmania many species of 

 a univalve spiral shelled mollusc so like ,the Bythinia of 

 Europe, Asia, North Africa, and North America, that I am 

 forced to include them in that genus, and believe that Aus- 

 tralia is not an exception to the world wide diffusion of 

 Bythinia. The Tasmanian species are all very small. 



1. Bythinia legrandi, 7i. s. B. testa minima, solidiuscula, 

 elongatu-conica, ejndermide incompleta, obscure olivacea, spira obtusa ; 

 anfractibus (5-5\) rotundatis, apertura producta integra, pellucida, 

 margine acuto. 



Shell small, somewhat solid, elongately conical, with an 

 obscurely olive, incomplete epidermis ; spire obtuse, whorls 

 (5 to 5|) rounded, aperture entire, produced, pellucid, margin 

 acute. Length, 2 ; breadth, 1 mill. 



Habitat, Brown's Eiver. 



This shell is distinguished by its size, solidity, obtuseness, 

 and few whorls. It retains these characters so constantly 

 under every circumstance that it cannot be regarded as a mere 

 variety. 



2. Bythinia PONTViLLENSis, ?i. s. B. testa turbi)iato conica, obtusa, 

 pellucida, 7iitula, fulvo-coruea epidermide pallide Intea, anfractibus, 

 (6) rotundatis, ultimo anfractu sub-inflato, apertura ovato, ab ultimo 

 anfractu disjuncta. 



Shell turbinately conical, obtuse, pellucid, shining fulvous, 

 horny, with a pale yellow epidermis ; whorls (6) rounded, 



