I'lllk : LICIIKNS OF TIIK MINNESOTA NAI-IK^'. li*.)5 



Cladonia pyxidata (L.) Fr., CTS. 



Cladonia fimbriata (L.) Fr., C. 



Cladonia fimbriata (L.) Fr. var. tubaeforrais Fr., TS. 



Cladonia gracilis (L.) Nyl., CTS. 



Cladonia gracilis (L.) Nyl. var. verticillata Fr., CTS. 



These two formations are remarkably similar, having 8 com- 

 mon forms (C) of a total of nine lichens in each formation. 

 Including the similar formation at Taylors Falls (T) we still 

 have 7 lichens common to the similar formations for a large 

 part of Minnesota, and extending the observation to the similar 

 formation on Grand Portage island in the lake Superior (S) 

 region, we yet have 6 lichens common to such formations selected 

 from widely separated areas in the State. This is the first kind 

 of formation thus far considered which is found in the Minne- 

 apolis area studied. Therefore data from this region have not 

 been introduced thus far. Their use in the present considera- 

 tion would not decrease the number of common elements, and 

 I shall not add them. The tliree rarer Cladonias of the region 

 under consideration in the present paper, Cladonia symphycarpta 

 Fr., Cladonia mitrula Tuck, and Cladonia cariosa (Ach.) 

 Spreng. have been purposely omitted, as there is yet doubt as 

 to whether their adaptation is ombrophytic. 



As to the nature of the lichens composing these earth lichen 

 formations, it is apparent that those of the shaded earth forma- 

 tions are as a whole more foliaceous or fruticulose and better 

 developed as to thallus than those of the exposed earth forma- 

 tion. The explanation is of course the same as that already 

 given for exposed and shaded rock lichen formations. 



I shall now consider the one remaining earth lichen formation 

 at Granite Falls and compare it with a similar one in another 

 region. It is that of the earth -among the calcareous drift peb- 

 bles and small boulders on hill sides. From the calcareous 

 nature of the earth and the presence of a Biatora seldom seen 

 elsewhere than in such formations, the following name has sug- 

 gested itself. 



Biatora dccipiens lichen formation of exposed calcareous earth 



(Granite Falls). 



Heppia despreauxii (Mont.) Tuck. 

 Heppia polyspora Tuck. 



