103 



Affinities and Differences. — The apex of the shell of Anci/lus 

 Australicus having a decided inclination to right, the shell is 

 sinistral, and, therefore, belongs to the genus Ancylus, and not 

 to Velletia. The present species is the first, so far as I am 

 aware, that has been recorded from this continent ; though no 

 less than three species have been described from Tasmania. Of 

 these, A. Cumingianus, Bourg., has no congener ; A. Tasmanicus, 

 T. Woods, is separable from our shell by its proportionately 

 greater height, and by its posterior apex; A. Woodsii, Johnston, 

 comes much nearer to it. A comparison of specimens of the 

 two species shows that A. Australicus differs in the following 

 chief particulars from A. Woodsii — It is of a much larger 

 size, is relatively more elevated and broader, and the apex is 

 excentric. 



Limnsea subaquatilis, spec. nov. Plate iv., figs. 6<z— 66. 



Shell thin, fragile, shining horn coloured ; ovate subven- 

 tricose whorls four longitudinally, but faintly wrinkled. Spire 

 short, pointed ; suture impressed. Aperture large ovate, half 

 the length of the shell. Columella fold thin, opaque white, 

 and reflected. 



Dimensions. — Total length, seven-twentieths of an inch ; 

 length of spire, two-twentieths of an inch ; length of aperture, 

 five-twentieths of an inch ; breadth, three-twentieths of an 

 inch. 



Habitat. — Among paludinal herbage growing on the marshy 

 margins of the River Torrens at Adelaide. 



This new species is allied to the Tasmanian L. DZuonensis, 

 T. Woods, but the last whorl is relatively narrower, and in 

 consequence the revolution of the whorls is less oblique. But 

 a species from the same island sent to me by Mr. Petterd, with 

 the manuscript name of Succinea Johnstoni comes very near to 

 our shell, if it be not identical with it ; however, the Tasmanian 

 specimens, which I have examined, are all young examples, and 

 it becomes difficult to give distinctive characters ; nevertheless, 

 in them the spire is more exsert, and the last whorl is slightly 

 flattened at the suture. Mr. Petterd informs me that his 

 S. Johnstoni lives among wet moss, a habitat not so dissimilar 

 from that in which L. subaquatilis has been found. 



Limnsea papyracea, spec. nov. Plate iv., figs. 5a— 5c. 



Shell oblong ovate, very thin, smooth and shining, pale horn- 

 coloured ; wrinkled transversely. Spire rather short, whorls 

 half -rounded at the sutures, last whorl ovate-oblong anteriorly 

 sub-expanded, outer lip sinuously produced about the middle. 

 Columella fold slender, slightly tortuous ; inner lip widely and 

 thinly spread. Pigs. 5« and 5b represent a large specimen 



