672 MINNESOTA BOTANICAL STUDIES. 
Lecanora subfusca (L.) Acu. 
Lecanora varia (Euru.) Nyt. 
Rinodina sophodes (Acu.) Nyt. 
Biatora atropurpurea (Mass.) Hepp. 
Biatora rubella (Euru.) RABENH. 
Lecidea enteroleuca Fr. 
Buellia parasema (Acu.) Tu. FR. 
Graphis scripta (L.) Acu. 
Arthonia lecideella Ny. 
Arthonia radiata (Pers.) Tu. Fr. 
Sagedia oxyspora (NyuL.) Tuck. 
Pyrenula punctiformis (Acu.) Nase. var. follax NyL. 
Pyrenula cinerella (FLor.) Tuck. var. quadriloculata Finx. 
Pyrenula leucoplaca (WAHL.) Kzr. 
Pyrenula leucoplaca (WAHL.) Ksr. var. pluriloculata var. 
nov. 
Inspection of the list of plants given above for the rough 
bark formations based on characters of substratum, shows 
lichens varying widely structurally and adapted to the forma- 
tion in very different ways. There are the Bzatoras, which 
usually occur in the more moist and shaded spots in this 
scattered formation and have small thalli usually without cellu- 
lar cortex. The same may be said of the Bxellzas and the 
‘Acolium, while the Lecanoras, Placodiums, and Pertusarias 
usually have somewhat larger thalli and some indication of an 
upper cortex at least. Even more rudimentary than any of the 
above are the thalli of the Opegraphas, Graphies, Pyrenulas 
and the Conzocybe which are hypophleeodal and thus protected. 
However the Col/emas without cellular cortex rise to the foli- 
aceous type, but seek very damp and well shaded habitats. 
The Leptogium, with upper cortex only, seeks damp places 
also. Next may be considered the Zheloschistes, Parmelias 
and Physczas with foliaceous thalli having good cortex on all 
sides, and which are not so closely adnate to the substratum as 
the crustaceous forms. Finally we have the fruticulose type of 
structure represented in the formation in the Aeamalinas and 
Usneas. These plants have a good cortex on all sides though 
not cellular at least in the first genus, and in well shaded and 
moist portions of the formation are quite common. This for- 
mation furnishes the most variety as to methods of adaptation 
of any herein recorded. 
