LIXNEAN SPECIES OF BRITISH NON-MARINE MOLLUSCA. 213 



Dr. Gwyn Jeffreys to conclude from bis observation of them that both 

 species were included in Muller's nitidus. Linne's description " subtus plana 

 omnino, sed parum cava versus centrum " is more applicable to Lightfoot's 

 fontanus than to his lacustris. 



Linne's name must, we think, be restored and the two forms be respec- 

 tively known as Planorbis (Hippeutis) complanatus (Linn.) and Segmentina 

 nitida (Mull.). As previously mentioned, three individuals of this last are 

 now in the collection, given, as we believe, by Miiller. 



Physa (Bulla, L.) fontinalis & 



Physa (Bulla, L.) hypnorom 

 are recognizable from the descriptions in the ' Fauna Svecica ' (2nd ed., 

 p. 523, no. 21G0 and p. 522, no. 2159 respectively). No example of either is in 

 the collection, but no doubts have ever been raised concemino- their identity. 



Paludestrina (Helix, L.) stagnalis. 



Linne in the 12th edition of the ' Systema ' (p. 1248, no. 697) introduced 

 the name " Helix stagnalis '* for Baster's Turbo stagnalis. As Hanle}' points 

 out, he afterwards noticing that he had already used the name for the well- 

 known pond-snail, altered it in manuscript in his own copy to Basteri*, 

 whilst Gmelin (Syst. 13th ed., p. 3653, no. 119) changed the trivial name 

 to stagnorum. 



Baster's species has been held to be identical with Pennant's Turbo ulvce, 

 and consequently his name being prior has been used in lieu of Pennant's. 

 We have shown, however (Proc. Malac. Soc. Lond. xii. 1907, p. 124), that 

 the species abounding at Baster's locality was identical with a form con- 

 sidered at the time on the authority of Dr. Johansen to be the Paludina 

 minuta of Totten. Totten's species, however, proves to be quite different, 

 and there is now reason to believe that we are here dealing with the Turbo 

 ventrosus of Montagu, vera, the form commonly passing under the name 

 being distinct. But this requires further research. 



Bithynia (Helix, L.) tentaculata (19, wrapped in a scrap of paper 

 bearing German print). 



We agree with Hanley that the description in the ' Fauna Svecica ' (2nd 

 ed., p. 531) and the reference to Lister's figure sufficiently determine this 

 species to be the form commonly accepted as such. 



In the first edition of the ; Fauna ' (p. 376, no. 1313) Linne contrasts it 

 "cum prseeedenti " (No. 1312) the Helix vivipara of the 2nd edition, but 

 neglected to make the necessary correction in the 2nd edition where five 

 other species have been intercalated. 



* Miiller, Verm. Hist. ii. p. 132 note, also calls attention to the double use by Linnt? of 

 Helix slagnalU, 



