THE BALTIC SEA 



343 



fluviatilis appeared, and also Littorina Uttorea and L. rudis, both now absent 

 from the Baltic Sea. At that time L. Uttorea reached 62° 20' N, while now it 



Fig. 1 70. Ice Lake and its role in the distribution of relicts (Sagerstrale, 1 957). 



1 Limit of ice cover (in the northern part, according to various authorities) ; 



2 Tentative location of ice cover ; 3 Watershed ; 4 Onega Ice Lake ; 5 Lake 

 deposits ; 6 Distribution of relicts (associated numerals denote altitude above 

 sea-level, m); A Lake Kenozero; В Lake Pochozero; С Lake Terekhovo; 

 D Latsha Lake ; E Kubensk Lake ; 7 Route of migrations of relicts ; 8 Cross- 

 distribution impossible for ecological reasons. 



does not go farther than Malmo, Warnemunde and Riigen. Rissoa mem- 

 branacea lived round the Aland Islands during the Littorina stage, while now it 

 does not east of Oresund. Phoca vitulina, which now does not go farther north 

 than Gotland, in the Littorina Sea reached 64° N in the Gulf of Bothnia. 



