355 

 NOTES ON THE SCANDINAVIAN MOLLUSCAN FAUNA. 



By J. DAVY DEAN. 



(Read before the Society, June i2th, 1912). 



I WANT, as far as possible, to sketch briefly in outline some features 

 relative to distribution in Scandinavia, and, without detailing too fully 

 the species or forms of the land and fresh-water mollusca, to endeav- 

 our to find out how far the fauna resembles, and how far it differs 

 from, our own. 



We have in vol. v. of this Joicrnal an excellent account by Miss 

 Esmark of the shells of Norway, and she gives some glimpses of the 

 difficulties to be surmounted before any serious distributional work 

 can be accomplished. There are also many valuable notes concerning 

 the range of particular species, which enable us to infer much as to 

 the comparative strength or weakness of the various forms. I have 

 not found myself quite in the same case with Sweden. Much of the 

 literature on the shells of this country is either obscure or in publica- 

 tions accessible only to those conversant with the Swedish language. 

 However, a number of the shells of Sweden and Lapland has recently 

 come into my hands, and these are very largely the basis of my notes. 

 The collection is one made by a Swedish naturalist — Herr A. H. 

 Christiernensen — between the years 1870 and 1901. Not only does 

 this collection reveal a power for discrimination between species, 

 which is everything in pioneer work, but it shows that Herr Christi- 

 ernensen realised the importance of exactly tabulating the locality 

 and date of specimens collected. Further, there is a series of Arctic 

 species from the Tornea Lappmark, the region visited by Linnseus in 

 1732. Herr Christiernensen was an oologist, but exactly where resi- 

 dent I do not know. All correspondence was done through Goteborg. 



The Scandinavian species may be divided into western and Teu- 

 tonic, as is the case with those of the British Isles. Extending far to 

 the north are the primitive groups of species which, at the time of the 

 earlier land-areas, spread through the Faroes and Iceland to North 

 America, and are now spoken of as the Circumpolar forms. Looking 

 at the fauna as a whole, we notice an absence of the true Helicellas, 

 and the presence of several Germanic or eastern Teutonic forms, such 

 as Hygrof/tia bidens Chem., Helicella strigella Drap., Torquilla avenacea 

 Brug., and Clatisilia plicatiila Drap. There are no land operculates 

 nearer than Jutland and Zealand, which are outside the scope of these 

 notes. A conspicuous absentee is Helix aspersa MiilL, absent also 

 from Germany. There are absent also Hygromia rufescens Penn, and 



