Ravkin Yu. S. RussiaNovosibirskInstitute of Systematics and Ecology of Animals, Siberian Branch of the Russian Academy of Sciences, 11 Frunze Str., Novosibirsk 630091, Russiazm@eco.nsc.ru Author's articles SPATIAL HETEROGENEITY OF THE ICHTHYOFAUNA OF NORTHERN EURASIA AND ITS BIOGEOGRAPHICAL DIVISION