FinJc : THE LICHENS OF MINNESOTA. 



713 



so many factors influence distribution of species that one can- 

 not predict with certainty the conditions in an unexplored 

 region, even when adjacent to one already well studied. 

 Further, the inference must not be hastily drawn that Minne- 

 sota as a state is comparatively poor in lichen-species, for, 

 while no one locality may finally yield so large a number 

 of species as Fayette, Iowa, with 220 already collected, yet 

 within the borders of the former state are included some areas 

 which are veritable gardens for certain species. As examples 

 may be mentioned the Glaclonias and Umbilicarias of the Lake 

 of the Woods, listed in the first paper of this series, and the 

 rock lichens of Taylors Falls already collected. 



The list of species to follow certainly contains all or nearly 

 all the species and varieties of lichens commonly occurring 

 about Minneapolis, as well as a large portion of rare ones. It 

 represents the lichen-flora of the area considered fairly well, 

 so that notes and comparisons on distribution may be safely 

 drawn from the list and observations made while collecting the 

 plants. However, a continued search should in time add 30 or 

 perhaps 40 species to the number here given for this area. 



It is worth while to note the difference in precipitation of 

 moisture for the two localities compared. This may be done 

 by a consideration of the following table, which gives the 

 yearly precipitation for St. Paul, Dubuque and Fayette, since 

 reliable records have been kept at these places. 

 TABLE OF PRECIPITATION. 



