The Lichen-Flora of Chicago and Vicinity. 



VViiiLiAM WiKT Calkins. 



INTRODUCTION. 



The following report, based upon my personal investigations, 

 collections and studies, during a period of many 3^ears, has been 

 prepared by invitation of the Board of Managers of the Geological 

 and Natural History Survey of The Chicago Academy of Sciences . 



As directed by the Board the report covers an area comprising 

 all of Cook and Du Page Counties, nine townships in the northwest 

 part of Will County, and a portion of Lake County, Indiana. This 

 territory might be thought sufficiently large to furnish an attractive 

 field and ample material for the investigation and study of lichens, 

 yet with the exception of the most common species, a few of which 

 are cosmopolitan in their habits, the explorer will meet with a dis- 

 appointment not to be experienced further south and west in 

 regions where the conditions of the soil, the geological features of 

 the country, and the climate favor a larger development of species. 

 Hence mountainous districts and the extreme South offer the great- 

 est variety of forms, those of Florida being largely semi-tropical 

 and identical with West Indian and Central American species, 

 especially in certain genera, as Graphis and Arthonia. However, in 

 the field under our consideration, enough varieties occur to form an 

 excellent preliminary course of study, fitting the student for larger 

 views and greater results when he has become familiar with the 

 Parmelias and Physcias which are so abundant on oaks and other 

 trees along the lake shore and in the ' ' wooded islands of the 

 prairies." 



