The Icelandic Forms of Limncea. 257 



amongst the pioneers of the great Siberian invasion which 

 repeated, in some respects, the important Oriental wave 

 which had preceded it ages before. Having once reached 

 Hungary and Roumania, its path to its present localities was 

 precisely that of Lycia hirtaria except that, as it arrived in 

 Europe long after that species, it found the route via Dalmatia 

 and Southern Italy to North Africa non-existent, hence it is 

 absent from these points. 



Two forms, which, in my eyes, do not rank as genuine 

 members of the genus Amphidasys, yet remain to be dealt 

 with, A. (?) thoracic aria and A. (?) tortuosa. These, in times 

 anterior to the appearance of A. cognataria, even in its old 

 world form, had come into being as a single mutation from the 

 oldest Amphidasyd stem, as we recognise from the primitive 

 wing pattern. Never enterprising, and not of any great vigour, 

 it had restricted its range to lands kept warm by the warm 

 Japanese current which plays the same role in the east as our 

 Gulf Stream does with us. Still, it had colonised Eastern China, 

 Corea and Japan long ere the latter country became an Archi- 

 pelago. However, in the end, as we know, Japan was severed 

 from the mainland, and with it was cut off, in part, the insect. 

 This portion has diverged from that left on the mainland 

 and has had the name A. tortuosa bestowed upon it ; the 

 remainder rejoices in the name of A. thoracicaria, but whether 

 the divergence is really of specific value is a matter for some 

 future zoologist of the East to elucidate. 



THE ICELANDIC FORMS OF LIMNiEA. 



HANS SCHLESCH, 

 Hellerup, Denmark. 



In the numerous hot springs scattered over Iceland Luir-aa 

 peregra Mull is very common. Besides this, the only other 

 species of the genus yet found is Limncea truncatula Mull. 

 Limncea peregra is a very variable species, and great care must 

 be exercised in introducing and describing new forms, a view 

 shared by the Norwegian conchologist, the late Miss Bertha 

 Esmark, who writes {Journal of Conchology, 1886, p. 116) of 

 this species as ' so changeable in form from two localities. 

 All these variations and transitions make it very difficult and 



doubtful how to deal with varieties I had the opportunity 



to collect them two succeeding summers on same place, but 

 they are not only* different the two years, but also each collec- 

 tion." Mr. Bjarni Saemundsson of Reykjavik kindly sent 

 me his finds of Limncea from his voyage in the Nordur and 

 Sudur Thingeyarsyslur in the North, during July-August, 1913, 



1917 Aug. 1. 



