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LICHENOLOGY OF ICELAND 
Gyrophora arctica, foliaceous lichen. 
— hyperborea, 
Stereocaulon denudatum v. pulvinatum, fruticose lichen. 
Taken as a whole, the liparite impresses one as being a very 
poor substratum for lichens. This fact is curious, considering that 
granite, which has the same chemical composition as liparite, is so 
rich in lichens. It must therefore be presumed, that the difference 
is due to physical conditions. 
