1916. No. 8. MOiNOGRAPH OF THE NORWEGIAN PHYSCIACEAE. 25 



part uncoloured or slightly shadowed with hyphae perpendicular to the 

 surface, otherwise uncoloured with hyphae of different directions. Gonidia 

 crowded in the margin, less numerous within the cortex, absent or verv 

 few under the hypothecium and in the medulla. Hypothecium uncoloured, 

 20 30 ju thick. Hymenium 80 100 (130)^ thick, epithecium yellowish- 

 brown, insperse, occasionally with crystals of oxalate of lime, otherwise 

 the hymenium is uncoloured and not insperse. Paraphyses slender, at 

 their ends clavately incrassate (5 f.t or less), indistinctly septate, undivided 

 or usually more or less branched. Asci clavate, rather narrow, 67 85 u 

 long, 15 17 /* thick, octosporous. Spores straight, elliptic, or sometimes 

 slightly flattened on one side, not constricted or only imperceptibly so at 

 the septum, with rounded apices. Cell rooms appro- 

 ximate, angular, and stretched across the spore 

 connected by a distinct canal. Spores shorter than 



in Ph. aipolia: 17,6 23,5 (25) U long, 8 IO,5 Fig. 4. Physcia stellaris 



IT 1,8) a thick. 



Pycnides numerous (but frequently sterile), located in the ends of the 

 laciniae (primary and secondary), and sometimes in the margin of the 

 apothecia. They are globose or later depresso-globose, with a prominent 

 ostiolum, 150 165 /t high and 150 240 broad. Perifulcrium black 

 around the ostiolum, otherwise uncoloured or only locally shadowed. 

 Pycnoconidia straight, cylindrical, 3 5 /< long. In the thickened black 

 part around the ostiolum is comprised the cortex as well as the peri- 

 thecium. 



Reaction: The cortex is coloured yellow by KOH, the 

 medulla remains uncoloured, no colouring by CaCl 2 O 2 . Hymenium 

 blue, then dark vinous or black by J (only in very young undeveloped 

 apothecia I have seen a persistent blue- colour). 



Physcia stellaris (L.) NYL. is much more monotypous than Ph. aipolia 

 (AcH.) NYL. Its varieties radiata and rosulata are founded on individual 

 variation more than on constant systematic differences, and probably on 

 different states of age. 



Owing to the slow growth of the Lichens the question of the 

 alterations of their habitus with the age has been little studied. Evidently 

 many adult plants preserve juvenile characters with great firmness. Some 

 Lichens, e. g. Ph. stellaris, normally have branched paraphyses, but in the 

 same specimen we can find apothecia with normal paraphyses, and others 

 (well developed) where undivided paraphyses are the rule. This is also 



