348 SYSTEMATIC 



is different from every other, and is special to these southern regions^ Dar- 

 bishire himself described 34 new Antarctic species, but only 10 of these 

 are from true Antarctica; the others were collected in South Georgia, the 

 Falkland Islands or Tierra del Fuego. Even though many species are 

 endemic in the south, the fact remains that a remarkable number of lichens 

 which occur intermediately on mountain summits are common to both Polar 

 areas. 



C. Lichens of the Temperate Zones 



Regions outside the Polar Circles which enjoy, on the whole, cool moist 

 climates, are specially favourable to lichen growth, and the recorded numbers 

 are very large. The European countries are naturally those in which the 

 lichen flora is best known. Whereas polar and high Alpine species are 

 stunted in growth and often sterile, those in milder localities grow and fruit 

 well, and the more highly developed species are more frequent. Parmeliae, 

 Nephromae, Usneae and Ramalinae become prominent, especially in the' 

 more northern districts. Many Arctic plants are represented on the higher 

 altitudes. A comparison has been made between the lichens of Greenland 

 and those of Germany : of 286 species recorded for the former country, 2 1 3 

 have been found in Germany, the largest number of species common to 

 both countries being crustaceous. Lindsay^ considered that Greenland 

 lichens were even more akin to those of Scandinavia. 



There is an astonishing similarity of lichens in the Temperate Zone all 

 round the world. Commenting on a list of Chicago lichens by Calkins'', 

 Hue' pointed out that with the exception of a few endemic species they 

 resemble those of Normandy. The same result appears in &ruce Fink's* 

 careful compilation of Minnesota lichens, which may be accepted as typical 

 of the Eastern and Middle States of North Temperate America. The 

 genera from that region number nearly 70, and only two of these, Omphalaria 

 and Heppia, are absent from our British Flora. The species naturally present 

 much greater diversity. Very few Graphideae are reported. In other States 

 of North America there occurs the singular aquatic lichen, Hydrothyria 

 venosa, nearly akin to Peltigera. 



If we contrast American lichens with these collected in South Siberia 

 near Lake Baikal^ we recognize there also the influence of temperate 

 conditions. Several species of Usnea are listed, U. barbata, U. florida, 

 U. hirta and U. longissima, all of them also American forms, U. longissima 

 having been found in Wisconsin. Xanthoria parietina, an almost cosmo- 

 politan lichen, is absent from this district, and is not recorded from Minnesota. 

 The opinion" in America is that it is a maritime species: Tuckerman gives 



1 Lindsay 1870. 2 Calkins 1896. 3 Hue 1898. * Fink 1903. 



" Wainio 1896. Comm. Heber Howe. 



