Fink: LICHENS OF NORTHWESTERN MINNESOTA. 675 



locality has only diminished the number of common species (C) 

 by one. Like the very similar Cladonia-Peltigera formation 

 recorded above, this one is especially developed under the 

 pines. Indeed, it hardly seems necessary to separate them in 

 the region now under consideration. 



The adaptations of the plants of the formation are similar to 

 those fully discussed under the Cladonia-Peltigera formation. 

 Briefly then, the Peltigeras, having only an upper cellular cor- 

 tex, lie flat on the substratum, while the Cladom'as, protected 

 on all sides by a pseudo-cortex, rise vertically and become 

 luxuriant in the moist and shaded habitat. 



Next in order I shall consider a number of formations some- 

 what studied in the Lake Superior region in 1897, but not yet 

 recorded for the state, as it was then found impossible to take 

 sufficient data in the rapid survey of a region fully one fourth 

 of whose lichen flora the writer had previously known only 

 through herbarium specimens or not at all. In the second sur- 

 vey of a somewhat similar region, I was able to take sufficient 

 field notes upon which to base an ecologic study of lichen for- 

 mations peculiar to the region as well as those previously 

 known. These formations, new to the state, will be recorded 

 for more than one place as far as possible. 



First of all I shall record the formation of the pine trees, 

 naming it for the Usnei group which give character to this 

 plant community : 



USNEI LICHEN FORMATION OF THE PINES (RED LAKE). 



Cetraria ciliaris (Acn.) TUCK, (cones). 



Cetraria juniperina (L.) ACH. var. pinastri ACH. 



Evernia prunastri (L.) ACH. (cones). 



Usnea barbata (L.) FR. var. florida Fr. 



Alectoria jubata (L.) TUCK. var. chalybeiformis ACH. 



Theloschistes chrysopthalmus (L.) NORM. 



Parmelia physodes (L.) ACH. 



Physcia tribacia (Acn.) TUCK. 



Physcia hispida (SCHREB., FR.) TUCK. 



Lecanora varia (EHRH.) NYL. (cones). 



Lecanora subfusca (L.) ACH. var. argentata (Acn.) (cones). 



Buellia parasema (Acn.) TH. FR. (cones). 



Calicium lucidum (TH. FR.) FINK. 



On approaching a pine woods one is impressed with an ap- 



