I92I. No. 7. STL-DIES ON THE LICHEN FLORA OF NORWAY. 181 



Hcd. Matrand (B. L.), Sander (B. L.), Jutulhugget (B. L.), Tron (B. L.), 

 Hodalen: Ky (B. L.), Helgoen (B. L.). Opl. Hundersæter (H.), Ringebu: 

 Sætern (Somrft.), Vaage common (H., B. L.), Lom (B. L.), Lunner: Snellin- 

 gen (Lid), Hadeland: Valbykampen (B. L.), Velmunden (B. L.). 



Sortr. Trondhjem: Berg (Gunn.), and Ladehammern (Kindt), Dovre 

 (LiNDS.), Knutsho (B. L.), Kongsvoll (Zett.), Fæmunden: Flcnskampen 

 (B. L.). 



Nordl. Rodo: Holandstjorden (Norm.), Steigen: Laskestad (Norm.). 

 Ti'oiiis. Gibostad (B. L.), Maalselven: Likkavarre (B. L.), Barde: Innset (B. L.); 

 Tromsø (Norm.), Lyngseidet (B. L.). Fiiiin. Alten: Skoddavarre (B. L.), 

 Store Raipas (B. L.), and Rautasvarre (B. L.); Kautokeino (Wbg.); Kjelvik 

 (GuNN.); Laksetjorden: Nordkyn (B. L.), Skjetningberg (B. L.), and Lebesby 

 (B. L.); Karasjok (B. L.); Tana: Berlevaag (B. L.), Vesterbugt (B. L.), and 

 Birkestrand (B. L.); Varanger: Thomasdal (Norm.), Jarfjorden (H.), and 

 Jakobselven (Norm.). 



Cetraria islaiidica is one of the most frequent lichens in Norway, 

 distributed over the whole country; perhaps a little less frequent in the 

 northernmost provinces and on the west coast. It ascends from the level 

 of the sea to far beyond the tree line. It prefers a dry substratum and 

 is accordingly especially abundant on the sandy fir-barrens of the moraine 

 districts, in light Piims silvcstcr forests where the soil is scanty (on primitive 

 rocks), on heaths, and at drv places in the mountains. Cetraria island iea 

 has a greater vertical distribution than C. nivalis, it is equall}' frequent in the 

 lowlands and on the mountains. But it never covers so vast areas as the 

 latter species which is in our country found in greater quantities than all 

 other Cetrarias together. — ^ It looks as if it were less frequent on chalky 

 substratum. 



If well developed var. plafyna is a conspicuous variety. But it is con- 

 nected with the type by numerous intermediate stages, and surely only 

 represents an extreme variation of the breadth of the laciniae. It is fre- 

 quently fertile. 



Var. platyna is an alpine variety. At least on the mountains of South- 

 ern Norway it is common, though by far not so frequent as the type. The 

 few stations recorded in our herbaria give no adequate idea of its distribution. 



Sterile specimens of Cetraria islandica are by far more frequent than 

 fertile ones, but apothecia are not rare. 



Apothecia lobis dilatatis antice affixa, ovalia, usque 13 — 14 mm. lata et 

 6 — 7 mm. longa, discus planus vel dein convexus, laevigatus vel rugosus, 

 castaneus, nitidus, epruinosus; margo tenuis, integer vel crenatus vel inci- 

 sus, dein exclusus (vulgo revolutus). Receptaculum plicato-rugosum, thallo 

 concolor, cortex receptaculi 20 — 45 [x crassus, parte exteriore rufo- vel flavo- 

 fuscescens, hyphae conglutinatae, perpendiculares, sat tenues, (4 — 5 p.), 

 pachydermaticae; cortex infrahypothecialis incoloratus, 25—40 \i. crassus, 



