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to be kept distinct from the find of Mytilus edulis\ as hardly 

 any resemblance may be said to exist but this that both species 

 are extinct at the northern East-Greenland, and that both 

 suggest a milder climate than the present — in time they may 

 be far apart. In the first instance we find the fragments of 

 valves of Pecten islandicus, which Hartz found, rounded and 

 rubbed, they must thus have been in a moraine or other glacier 

 bed, and nobody knows how old these deposits may be. Moreover 

 the height at which these fragments were found is indeed 

 equal with the greatest height at which Mytilus edulis occurs, 

 but this height is according to Hartz the secondary height, 

 and nobody knows at which height the original bed has been 

 situated. Fecten islandicus need on the other hand not to 

 indicate so genial a period as Mytilus edulis and may conse- 

 quently be found on a higher (colder and for this reason older) 

 niveau than the last mentioned species. There is a certain 

 probability that both species belong to the same genial period, 

 but it is nothing but a probability. 



These finds from the west- and the east-coast make Green- 

 land one of the northern countries, where we have been able 

 to prove, that the climatic conditions have been milder during 

 a period of the quaternary time than they are at present. 



An extinction in post-glacial time of certain mollusc-species 

 which compared with the present faunas must be called southern 

 species has by and by been pointed out from the following 

 areas: The Baltic, the Danish waters, Bohuslän, the southern 

 and western Norway (the «Littorina»- or the «Tapes»-time); 

 Scotland ("Pecten-maximus bed"); the northern Iceland (deposits 

 with Purpura lapillus)\ the north-coast of Russia (deposits with 

 Cardium edule^)). At last we find as far north as Spitzbergen 



') On a previous occasion (Vidensk. Medd. Naturhist. Foren. Kbhvn. 1905, 

 p. 29) 1 liave called attention to the fact that molluscs whose present 

 limit of distribution is situated rather westerly were found in a fossil 

 state still further east, at the lower Jenisei by the Russian Mammuth-Ex- 



