670 MINNESOTA BOTANICAL STUDIES. 



Endocarpon pusillum HEDW., C. 



Verrucaria nigrescens PERS. 



Verrucaria muralis ACH., C. 



The lichens of the above formation have small thalli, closely 

 adnate or even more or less strictly hypolithic. All except the 

 last Verrucaria, which is hypolithic, and Lecanora -pri-vigna 

 (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 (EHRH.) TUCK. 



Theloschistes lychneus (NYL.) TUCK. 



Theloschistes concolor (DICKS.) TUCK. 



Theloschistes concolor (DICKS.) TUCK. var. effusa TUCK. 



Parmelia crinita ACH. 



Parmelia borreri TURN. 



Parmelia tiliacea (HOFFM. ) FLK. 



Parmelia saxatilis (L.) FR. 



Parmelia saxatilis (L.) FR. var. sulcata NYL. 



Parmelia olivacea (L.) ACH. 



Parmelia olivacea (L.) ACH. var. sorediata (Acn.) NYL. 



Parmelia caperata (L.) ACH. 



Physcia speciosa (WULF., ACH.) NYL. 



Physcia hypoleuca (MUHL.) TUCK. 



*Fink, B. 1. c., 302-305. 



