ScHARFF — Oil the Origin of the European Fauna. 455 



Professor Sars' work, but none of these or the Mysidae seem to range 

 heyond the Black Sea. It was formerly believed that Mysis relicta 

 of the Arctic Ocean, inhabited the Caspian, but this does not appear 

 to be the case ; however, the nortliern marine Isopod, Idotea entomon 

 has been shown to exist in it. Moreover, a closely allied form of the 

 Arctic seal, viz. Phoca caspica, lives in the Caspian, while the Caspian 

 herring {Clupea caspica) is related to the northern herring, and a 

 still more closely allied species, Clupea pontica, occurs in the Black 

 Sea. 



EUROPEAN 

 RUSSIA 



4. — Map of European Russia (after Karspinski). Tlie faintly clotted parts 

 indicate the former extension of land-ice, the strongly dotted ones 

 represent the Aralo-Caspian and other post-Pliocene basins. 



These latter species are certainly of northern origin, but of the 

 €rustaoea mentioned by Professor Sars, we can only say that they have 

 •certainly descended from marine ancestors. The probability, however, 

 is strongly in favour of their having entered the Caspian area from the 

 north, since it has been proved by Professor Suess (83, vol. i, p. 437) 

 that the Black Sea and Caspian were, until quite recent times, certainly 



