LECANOUA. 



223 



membranaceous-cartilaginous or tartareous, areolate-tubercu- 

 lose. Apothecia naked ; margin tumid, becoming thin, often 

 inflexed. (E.B. 156, var. saxorum) The "Orn-massa" of 

 Sweden and Norway. 



A common montane and alpine species, growing on boul- 

 ders and rocks in Highland districts and on Highland moun- 

 tains. The thallus is frequently sterile, sorediiferous or 

 isidioid ; it is usually thick, friable, and mealy, its tubercles 

 varying in size, but always densely aggregated. The apo- 

 thecia are generally large, often confluent, and very irregular 

 in form, having usually flexuose, thick, incurved margins ; 

 they may be concave or flattened. It appears to prefer gra- 

 nitoid rocks and exposed situations. We have found it in a 

 sterile state, along with other subalpine or alpine species, 

 on large micaceous boulders on the hills, at a slight eleva- 

 tion above the sea, around Perth. It is to be presumed 

 that the Lichens have been developed subsequently to the 

 removal of the boulders from their origin — probably the Dun- 

 keld Highlands, fifteen miles off — to their present resting- 

 places ; hence this example would tend to indicate that the 

 nature of the rocky habitat has frequently more to do than 

 climate with the growth of some montane or alpine species. 

 A variety grows sometimes on trees in alpine woods ; and a 



