ARKIV FÖR ZOOLOGI. 



BAND 8. N:o 25. 



Ptisanula linmseoides, a Neiv Arctic Opistho- 



branchiate Mollusc, its Anatomy 



and Affinities. 



By 

 NILS HJ. ODHNER. 



With one plate. 

 Coramunicated December 3d bv Hj. Théel and E. Lönnberg. 



In 1910 Professor G. De Geer published a note on a 

 fossil Gastropod from the Quaternary shell-deposits at Ka- 

 pellbacken, Uddevalla. As it apparently belonged to a 

 new genus, I decided upon giving a description of it låter on 

 and named it for the time being Ptisanula limnaioides. 1 It 

 seemed to be identical with a recent species from Spitzbergen 

 that I had already observed in the Riksmuseum collections, 

 but I was unacquainted with its relations, they being only 

 to be established by close investigation and research. The 

 characters of the shell in evidence were not sufficient to 

 enable me to state its systematical position, and the radula, 

 obtained from the dried animals, which vere fortunately 

 present in the shells, exhibited a peculiar shape but afforded 

 no basis for drawing conclusions on its affinities. In the 

 Riksmuseum collections, however, I did find some further 

 specimens of the new form, preserved in alcohol, and they 

 enabled me to make an examination of the exteriör morpho- 

 logy of the soft parts as well as of the inner anatomy of one 



1 Ptisanula limnoides in De Geer 1910. 

 Arkiv för zoologi. Band 8. N:o 2~>. 



