16 THE CHICAGO ACADEMY OF SCIENCES. 



discoveries in chemistry did away with their use in civilized 

 nations. Lichens were once valued highly as remedies for various 

 diseases, and some species are still used, as Peltigera canina. 

 Theloschistes parietinus, Cladonia aphthosa, and numerous other 

 forms of various genera, all common to our own country and 

 easy of investigation by students. 



LICHENS OF THE TERRITORY INCLUDED IN THK SURVEY. 



The species enumerated are represented in the " Exsiccati of 

 North American Lichens," deposited in the collection of the Chi- 

 cago Academy of Sciences by the author. The descriptions of 

 species are made from studies of the specimens, comparisons, and 

 study of other authors. 



