Fink : LICHENS OF THE MINNESOTA VALLEY. 293 



lichens (S) of it found in the corresponding ones considered 

 above, subtracts none from the number of common species. 

 Therefore, these eight lichens may be regarded as the elements 

 of that portion of the shaded rock lichen formations which have 

 probably migrated from trees, most widely occurring in such 

 formations over the state. Only one day was spent in study- 

 ing the New Ulm formations. A second day would have added 

 somewhat to the list, yet doubtless all the dominant lichen floral 

 elements were secured. 



Without entering into a detailed analysis, it will appear from 

 an inspection of the lichens composing the formations for shaded 

 and for exposed rocks that the species occurring in the former 

 are for most part foliaceous or fruticulose types, while those 

 given for the latter are in general crustaceous, or if foliaceous, 

 at least closely prostrate on the rocks. This is what would be 

 expected, since shade favors better development of thallus, so 

 that those species showing good thalli crowd out the other 

 species in shaded places, or when unshaded become shaded with 

 the growth of trees. 



Next in order come the earth lichen formations of the rocky 

 areas of Granite Falls and New Ulm. I shall first record the 

 exposed formations for the two localities and compare with the 

 similar formation already recorded for Pipestone. Then will 

 follow the lichen formations of shaded earth at the first two sta- 

 tions, which is scarcely developed at Pipestone. A consid- 

 eration of calcareous-earth lichen formations follows, the pres- 

 ent being formations of non-calcareous earth. 



Endocarpon hepaticum lichen formation of exposed earth 



(Granite Falls). 



Heppia despreauxii (MONT.) TUCK. 

 Urceolaria scruposa (L.) NYL. 

 Cladonia pyxidata (L.) FR. 

 Biatora muscorum (Sw.) TUCK. 

 Biatora icterica MONT. 

 Endocarpon hepaticum ACH. 

 Endocarpon pusillum HEDW. var. garovaglii KPH. 



Endocarpon hepaticum lichen formation of exposed earth 



(New Ulm). 



Cladonia pyxidata (L.) FR., CTS. 



