303 



post-glacial deposits v/ith well developed Mytilus edulis^ Cyprina 

 islandica and Littorina littorea which now-a-days do not occur 

 in living state at this archipelago. Littorina littorea has at 

 present its northern and eastern limit at the Finmark and in 

 the White-Sea, Mytilus edulis does not go further than at 

 Nowaia-Zemlia, and Cyprina islandica stops at the western part 

 of the Murman-Sea. Fossil Mytilus edulis have also been found 

 on Svenska-Förlandet and on Franz Joseph-Land ^). 



It becomes more and more evident that we have not to 

 deal with a local phenomenon, but that these climatic changes 

 have influenced a great part of the northern hemisphere. If 

 all of them have taken place precisely at the same time we do 

 not know yet. 



If we again turn to the opposite side of the Atlantic we 

 will come across a strange phenomenon at the coast of Canada 

 which likewise seem to be in connection with a post-glacial 

 more genial period. Prof. A. E. Verrill has shown that there 

 are genuine colonies of southern species in the Gulf of St. 

 Lawrence (from Chaleur-Bay to Prince Edward-Island and Cape 

 Breton Island) and on the coast of Maine (Quahog-Bay), which 

 are completely isolated from their co-species of the southern 

 coast of New-England, and surrounded on all sides by more 

 northern forms. And he tells us further, that at an earlier 

 period these colonies were much more extensive. The shells 

 of the round clam or «quahog» (Venus mercenaria) are abundant 



pedition of 1866 and by the Vega-Expedition. The species in question 

 were as follows: Tellina balthica L., Cyprina islandica L., Zirphaea 

 crispata L. and Buccinum undatum L., none of these species reach 

 at present the Kara-Sea. 



References to the literature dealing with this subject may be found in 

 my short treatise on Cyprina islandica (1. с 1902). N. Knipowitsch 

 has later given detailed information regarding the Swedish expeditions' 

 collections of postglacial molluscs from Spitzbergen (Ann. du Musée 

 Zool. de I'Acad. Imp. d. Sei. St. Pétersbourg, T. VIII, 1903, p. 133—143). 

 Comp, moreover G. deGeer: Die Gletscher von Spitzbergen; Verhandl. 

 d. 7. internat. Geographen-Kongresses, II, p. 299— 302. Berlin 1901. 

 ixix. 20 



