82 BERNT LYNGE. M.-N. Kl. 



Pycnides numerous, but fertile ones were searched after in vain. 

 React, as in Ph. lithotea. 



Hab. and loc. Only recorded from one Norwegian station: Hog- 

 skarhus in Dividalen, inner part of the Tromsø district in Northern Nor- 

 way, growing on large flat stones on the banks of the river, submerged 

 at flood-tide. 



The scarcity of my material has prevented me from making any 

 observations as to its variability. The late and much regretted Finnish 

 lichenologist, Mr. Lang, sent me some specimens from Finnish and Swe- 

 dish Lapland; according to Mr. Lang it should be frequent there. His 

 plants agree well with the Norwegian ones, but they have narrower laci- 

 niae. In one of them the lower part of the medulla was locally coloured 

 yellowish red (purple by KOH). 



There is a margo proprius round the hymenium, but I have not been 

 able to find the »margo thallinus« described by Nylander in Flora 1875, 

 p. 360. — Nylander measured longer and narrower spores: 17 — 23 X 

 6— 9^< . 



Separated from Physcia lithotea by the paler colour (?) which seems 

 to be normal in var. lithotodes, by convex laciniae and by the placodium- 

 like thallus. The upper cortex is thinner than in Ph. lithotea and the 

 green colour more visible in moistened plants. The disposition to form 

 isidia is very weak, but not quite absent. Initiating sciastra-Wke isidia are 

 found in the Finnish as well as in the Norwegian plants. 



It is possible that a rich material would contain intermediate forms 

 between var. lithotodes and the naked forms of Ph. lithotea; in that case 

 var. lithotodes would be reduced to a mere individual variation. But Mr. 

 Lang who studied it in nature and whose opinions were worthy of the 

 greatest attention, considered it to be a good variety, perhaps even a 

 proper species. — Its geographical distribution also seems to be well 

 limited: The continental parts of Northern Fenno-Scandia. 



13. Physcia tremulicohi Nyl. 



Physcia tremiilicola Nylander Addenda Nova XVII Flora (1874) p. 7. 

 Olivier Lieh. d'Europe I (1907) p. (169) 245. 



Ex sic. Havaas Lieh. Norv. (inédit). Norrl. et Nyl. Herb. Lieh. 

 Fenn. 217. 



