186 OLAF GALL0E 



tion to heath-vegetation. An instance of this is also given below 

 under the description of heaths (Type III). 



We shall elsewhere - - under the description of Iceland's moss- 

 carpels and their lichens, - have an opportunity of discussing the 

 competition between moss and lichen. Here it will suffice to state, 

 that lichens, in the loose soil of mountain -bights, in mountain- 

 deserts, rarely occur on quite bare, purely inorganic soil. They 

 show a peculiar tendency to seek company with mosses or other 

 plants, without its being always possible to state precisely, which 

 have been the first to arrive on the spot. 



The species which appear to be most common on loose soil 

 in mountain-deserts are the following: 



Cladonia turgida (fruticose lichenX frequently sterile. 



pyxidata , on humus, 



rangiferina 

 cocci fera 



Stereocaulon denudatum - 

 Alectoria nigricans 



Thamnolia vermicularis - , sterile. 



Cetraria hiascens (foliaceous lichen), frequently sterile, 

 islandica 

 Fahlunensis 



aculeata (fruticose lichen), 

 Solorina crocea foliaceous lichen), 

 Pannaria microphylla 

 Peltigera aphtosa 



lepidophora 



Dermatocarpon hepaticum - , on moor-soil. 



Lecanora tartarea (crustaceous lichen), fertile; on moss, moor-soil 

 and lichens. 



Bacidia flavovirescens (crustaceous lichen), often sterile; on purely 

 inorganic soil. 



Pertusaria oculata (crustaceous lichen), often fertile. 

 Buellia parasema 



v. papillata, fertile ; on moor-soil, 

 v. triphragmia, fertile, 

 liinodina mniaroea (crustaceous lichen) 



v. cinnamomea, fertile; on moor-soil. 



Lecidca assimilata crustaceous lichen), fertile; on dead moss. 

 C.nloplaca Jungermanniae , fertile; on moor-soil. 



I'soroma liypnorum . fertile: on moss. 



Lecanora caslanea . fertile; on moor-soil. 



r,;ioiii\ ces hyssoides , often sterile; on moor-soil 



rich in miner;:!. 



