29G MINNESOTA BOTANICAL STUDIES. 



Urceolaria scruposa (L.) Nyl. 



Biatora muscorum (S\v.)Tuck. 



Biatora decipiens (Ehrh.) Fr. 



Biatora decipiens (Ehrh.) Fr, var. dealbata Auct. 



Endocarpon hepaticum Ach. 



Some of the plants of this formation have been found at 

 Mankato and also at Minneapolis, but the formation is not well 

 developed at either place. However, it is beautifully developed 

 at Fayette, Iowa, and because of its remarkable similarity there 

 to the Granite Falls formation about two hundred miles distant, 

 I give it below for the sake of comparative study. 



Biatora decipiens lichen formation of exposed calcareous earth 



(Fayette, Iowa). 



Heppia despreauxii (Mont.) Tuck., C. 



Urceolaria scruposa (L.) Nyl., C. 



Biatora muscorum (Sw.) Tuck., C. 



Biatora decipiens (Ehrh.) Fr., C. 



Biatora decipiens (Ehrh.) Fr. var. dealbata Auct., C. 



Biatora fossarum (Duf.) Mont. 



Endocarpon hepaticum Ach., C. 



It will be seen that the two formations are identical except 

 that each one contains one species not found in the other. 

 Again, this slight difference becomes less significant when it is 

 stated that each of these two plants not found in both formations 

 is rather rare in the formation in which it occurs. The six 

 lichens common to both formations I have indicated in the Fay- 

 ette list (C). In both localities the formations are formed on 

 hill sides and seen to be somewhat better developed on south- 

 ward than on northward slopes. I have not seen similar forma- 

 tions well developed elsewhere, but it is probable that they 

 reach their best development on unshaded hill sides where other 

 vegetation is scanty and where the lichens are washed with 

 lime-impregnated water flowing down the slope during rains. 

 Biatora decipiens (Ehrh.) Fr. ^nd. Endocarpon hepaticum Ach. 

 are the most common plants of these formations, but the latter 

 is quite as common in another formation of non-calcareous earth, 

 which I have named for it, not confined to hill sides. 



