Cryptic immigrants are common species incorporated in near-natural biocoenoses that occur only in Holocene, mostly very recent deposits, being absent from older (Pleistocene) formations. This is true of Alinda biplicata, Oxychilus cellarius and other presented species. This also applies to isolated occurrences of Itala ornata or Cochlodina commutata that entered the Bohemian Uplands by aerial dispersal from the south. In the Pleistocene, the very early appearance of some southern species (e.g. Drobacia banatica) from the very be-ginning of the interglacial periods is reminiscent of modern snail invasions. How-ever, the former was initiated by the abrupt increase in temperature and moisture., Vojen Ložek, and 1 barev. fot., 10 čb. fot.