CONTENTS 



Page 



Introduction r 



Family Ariouidar 3 



Genus Arioii ' 4 



Key to the Norwegian Arions, as regards external characters 11 



Key to the Norwegian Arions, from the reproductive organs 12 



Aiion atcr 13 



Ar ion sub fusens 24 



Ar ion circmuscriptns 32 



Arion hortensis 40 



Arion intermedins 46 



Summar\' of results 52 



Appendix to maps 55 



Literature 58 



Explanation of plate 62 



