THE SIBERIAN MIGRATION. 223 



years announced that the tract on this eastern side of 

 the mountains was covered by freshwater deposits, 

 his discovery seemed once for all to settle the problem 

 of the arctic marine connection in the negative. As 

 Professor Dawkins's theory has, however, received 

 much additional affirmative evidence by current 

 faunal researches, a connection between the Caspian 

 (or Aralo-Caspian) and the Arctic Ocean (White Sea) 

 may have actually existed within recent geological 

 times. 



What relict lakes are, has already been explained 

 (p. 176), and their fauna will again be referred to in 

 a subsequent chapter. I might perhaps be allowed 

 to repeat that such lakes are supposed to have been 

 flooded by, or to have been in close connection with, 

 the sea at some former period. Many of the Swedish 

 lakes are spoken of as relict lakes (Reliktenseen), 

 because they contain a number of marine species of 

 animals which have now become adapted to live in 

 fresh water, but all of whose nearest relatives inhabit 

 the sea. One of these, the schizopod crustacean Mysis 

 relicta, a shrimp-like creature, which was formerly 

 believed to inhabit also the Caspian, is of particular 

 interest. More recently, the occurrence of this Mysis 

 in the Caspian was denied, but though this denial has 

 been confirmed by Professor Sars in his memoir on 

 the crustaceans of the great Russian inland sea, he 

 has been enabled to add two new species of Mysis 

 to the list of those already known to science. These 

 are M. caspia and M. micropthalma, and both are 



