1916. No. 8 MONOGRAPH OF THE NORWEGIAN PHYSCIACEAE. 75 



great south-eastern valleys. Northern limit Ibbestad and Malangen in 

 Troms amt. 



Abundant about Kristiania : Teien, Akershus (BLYTT), Naesodden (Mos), 

 Aker, Baerum and Asker (LYNGE; at Leangen on chalk), Haaeen (BLYTT), 

 Drammen (Ki^R), Hakedalen (LYNGE), Minne (also on stone, LYNGE), Modum 

 (MOE), Ringerike: Sundvolden (HAVAAS), Brandbu and Vestfjorddalen (LYNGE), 

 Toten, Ringebu and Vaage (SOMMERFELT), Drivstuen on Dovre (LYNGE). Abun- 

 dant along the south and west coast, on trees and stone : Larvik (NORMAN), 

 Lynger (LYNGE) Moster and Granvin (HAVAAS and LYNGE). Voss: Bjergum, 

 Vangen and Graasiden (LYNGE). Abundant about Trondhjem: Sorgenfri 

 (LYNGE), Frosta ( JSRSTAD). Salten : (SOMMERFELT), Steigen (NORMAN). North 

 of Lofoten it is evidently rare, recorded only from maritime chalky rocks 

 at Havnvik in Ibbestad and Nordbynesset in Malangen (LYNGE). 



The thallus is sometimes suffused with small yellow patches, coloured 

 violet by KOH, when growing associated with Xanthoria parietina. This 

 is due to chrysophanic acid, produced by the said Lichen. Such forms 

 are entirely incidental and not entitled to a proper name (f. flavescens 

 CROMBIE Brit. Lich. I, p. 320). 



Very convex laciniae are occasionally found. We might expect to find 

 pycnides in them, but they are due to a strong growth of the gonidia, 

 accompanied by a corresponding growth of the cortex, which is not as 

 usual broken up and soredia formed. 



Great importance has been attributed to the black colour of the lower 

 side. It is, indeed, a remarkable, but in my opinion no decisive character. 

 Though not frequently, I have found Ph. virella with a pale lower face, 

 especially at the circumference. Owing to the contiguous or imbricate 

 laciniae the black rhizines are but slightly visible. 



In one apothecium I found 6-celled spores of a very varying size : 

 21 39 X 9> 2 1 3>5 I- 1 ' The spores of Ph. virella are somewhat smaller 

 than in Ph. obscura. On the whole the structure of the organs of fructi- 

 fication agrees well in the two species. They have been treated here as 

 two species, owing to the difference of the morphological characters. 

 Different colour and habitus, longer and more appressed laciniae in Ph. 

 obscura and the never absent rhizines on the receptacle of Ph. ocscura. 

 The two species were separated as proper species by ACHARIUS in his 

 Prodromus as early as in 1798, later authors have often confounded them, 

 neglecting external characters and only acknowledging carpological charac- 

 ters as important. 



