During the last two decades a great number of studies dealing witharctic and boreal spiders have been published, both in thePalaearctic and the Nearctic. Such an increase in informationmakes it possible to analyze basic patterns of spider diversity inthe North as well as to show areas where further studies are stillnecessary. The number of species found in faunas of larger areasnorth of 60 degree N varies from 620 (Finland) to 250 (PolarUrals) and 300 (Yukon), when island faunas are excluded. Twoareas, divided by the Bering Strait, Northeastern Siberia andnorth-western North America have marked proportion of endemic taxa(ca. 8 %) belonging to several spider families. Considerablenumber of endemic spiders are known also in Middle Siberia. [...]
