670 MINNESOTA BOTANICAL STUDIES. 
Endocarpon pusillum HEpw., C. 
Verrucaria nigrescens PErRs. 
Verrucaria muralis Acu., C. 
The lichens of the above formation have small thalli, closely 
adnate or even more or less strictly hypolithic. All except the 
last Verrucarza, which is hypolithic, and Lecanora privigna 
(Ach.) Nyl., which has a very rudimentary and evanescent 
thallus have more or less of a cellular or pseudocellular cortex 
above. None except the first Lecanora, which has the largest 
thallus in the formation, showed any indication of such structure 
below. ‘The upper cortex gives these better developed but still 
small thalli sufficient protection against evaporation and adapts 
them to their dry station. 
The lichen formation for trees with rough and smooth bark 
at Bemidji are in general quite like the corresponding ones 
recorded for Mankato and Granite Falls,* but are rather richer 
in species. I record them below as they may be of use in the 
further study of the lichens of northern Minnesota. 
PARMELIA LICHEN FORMATION OF TREES WITH ROUGH BARK 
(BEMIDJI). 
Ramalina calicaris (L.) Fr. var. fastigiata Fr. 
Ramalina calicaris (L.) Fr. var. fraxinea Fr. 
Usnea barbata (L.) Fr. var. florida Fr. 
Theloschistes chrysopthalmus (L.) Norm. 
Theloschistes polycarpus (Euru.) Tuck. 
Theloschistes lychneus (Nyu.) Tuck. 
Theloschistes concolor (Dicxs.) Tuck. 
Theloschistes concolor (Dicxs.) Tuck. var. effusa Tuck. 
Parmelia crinita Acu. 
Parmelia borreri TuRN. 
Parmelia tiliacea (Horrm.) Fix. 
Parmelia saxatilis (L.) Fr. 
Parmelia saxatilis (L.) Fr. var. sulcata Nyv. 
Parmelia olivacea (L.) Acu. 
Parmelia olivacea (L.) Acu. var. sorediata (AcH.) Nyt. 
Parmelia caperata (L.) Acu. 
Physcia speciosa (WuLF., Acu.) Nyt. 
Physcia hypoleuca (Munv.) Tuck. 
Eiken leiCs 302—-205¢ 
