174 HISTORY OF THE EUROPEAN FAUNA. 



beds exist; there is, however, not a trace in any 

 of them of any American mollusca. In examin- 

 ing the marine deposits of St. Erth, on the coast of 

 Cornwall, which are believed to be of about the same 

 age as the newer crags, Messrs. Kendall and Bell 

 were much struck by the absence of the species 

 characteristic of the latter. The St. Erth fauna led 

 them to believe that the Arctic Ocean could not 

 then have opened into the Atlantic, but that a land- 

 communication had existed between Europe and 

 North America, so as to form a barrier of separation 

 between the two oceans. This again perfectly har- 

 monises with the views I have expressed, and 

 supports them. 



Let us now look a little more closely at the 

 history and the fauna of the Baltic and the adjoining 

 lakes, in order to gain additional information as to the 

 geographical changes which have had such lasting 

 influence on the peninsula of Scandinavia, The 

 Baltic is a shallow sea covering an area of 184,496 

 square miles, and its waters are decidedly brackish. 

 The fauna is a poor one, being too salt for the purely 

 freshwater species and not salt enough for the typical 

 marine forms. The absence of some animals which 

 we should expect to find there is one of the remark- 

 able features about the Baltic, but, on the other hand, 

 some species occur which are altogether strangers to 

 the fauna. And these, moreover, are confined to the 

 extreme northern end of the sea. I need only refer 

 to the Arctic Seal (P/wca annelata), which is confined 



