234 ZDENEK CERNOHORSKY 



conspicuous macrolichen species, known either from the northern coasts of 

 these islands or concentrated there in a remarkable manner. It is to be stressed 

 that the climate of the northern coast of Svalbard is highly arctic. One of the 

 most interesting cases is the genus Dactylina, represented there by three 

 species: Dactylina arctica (Richards.) Nyl., D. madreporiformis (Wulf.) Tuck., 

 and D. ramuJosa (Hook.) Tuck. From the maps (Lynge, 1933) we perceive 

 that they have an enormous distribution in the world, but that this distribu- 

 tion is not continuous. They are unknown from large areas within their 

 limits, e.g. there is a wide gap between the occurrence of Dactylina madre- 

 poriformis in Svalbard and in the high mountains of central Europe. Lynge 

 (1938) concludes that they are very old relict plants which no doubt formerly 

 had a wider distribution. Later, their area was reduced, resulting in these 

 great gaps, although we have no fossil records to support this hypothesis. 

 On the other hand, the comparison with some higher plants, known as 

 fossils from previous geological periods, shows that this conclusion is reason- 

 able. 



From other north coast lichens Lynge (1938) indicates some conspicuous 

 species of the genera Parmelia and Cladonia. To explain their existence on the 

 north coast of Spitsbergen and North East Land he undertakes an analysis 

 of their distribution in Norway. This analysis shows that only Parmelia 

 intestiniformis (Vill.) Ach. is High Alpine. Most of the species are Sub- 

 Alpine, with the weight of their distribution in the more continental Norwegian 

 forest zone. Judging from their distribution in Svalbard and in Norway it can 

 be assumed that they have great amplitude in their demands upon Hfe and that 

 time is the main factor in explaining their presence on the north coast of 

 Spitsbergen and North East Land. As far as the existence of these species in 

 Svalbard is concerned, Lynge draws the following conclusion: "... their 

 area, or part of it, should have been ice-free refugia during the last glaciation, 

 perhaps all through the time subsequent to the Tertiary Age, and that these 

 lichens should be relics which have persisted, at least, from the Last 

 Interglacial down to the present time". 



Some of the indicated north coast lichens of Svalbard grow in central 

 Europe as well, e.g. Parmelia centrifuga (L.) Ach. It is very rare, having its 

 southern distribution limit here. Parmelia centrifuga is to be found on summits 

 and ridges of mountains (Harz; a broad area of Riesengebirge, mostly at an 

 ahitude of 1000-1500 m; Bohmerwald at 820-850 m; the Alps at 1900-2000 

 m). As a rule it is sterile and does not reproduce here. l\\ case it does re- 

 produce, it is by means of thallus fragments. Parmelia centrifuga is fertile only 

 in Harz and in Bohmerwald. No doubt it reproduces in Bohmerwald but its 

 distribution there is limited. In central Europe its locahties are scattered 

 around the 50th parallel ; they indicate a possible, more or less close relation 

 to the border of the greatest glaciation. As the last glaciation was relatively 

 small, Parmelia centrifuga hardly penetrated into central Europe from the 



