GENERAL INTRODUCTION 



This volume is the first to appear of a series on the zoology 

 and cryptogamic botany of the State of Illinois, author- 

 ized and provided for by the Thirty-fourth General Assembly.* 



The series is intended to summarize the facts relating to the 

 natural history of Illinois which have been accumulated by 

 general investigations made in the districts of which the State 

 forms a part, by the studies of local naturalists, and by the 







operations of the State Laboratory of Natural History. 



The work of this institution has been especially directed, dur- 

 ing the past twelve years, to the supply of the more important 

 deficiencies remaining in our knowledge of the zoology and 

 botany of the State. Neglecting the flowering plants and the 

 classification and description of birds and mammals, already 

 fairly well studied for this region, we have paid particular at- 

 tention, so far as descriptive work is concerned, to the lower 

 plants, to reptiles, amphibians, and fishes, and to insects and 

 aquatic invertebrates. Still greater prominence has been given 

 to a general research on the system of actions and reactions 

 occurring within the assemblage of living forms native to 

 Illinois, with a view to exhibiting the laws of interaction and 

 coordination by which the innumerable host and vast variety of 

 the plants and animals of our region are held together as a 

 definitely organized, living whole. 



As an item of this research the economic relations of the 

 most important groups, especially of birds, fishes, and insects, 



*Laws of the State of Illinois, 1886, p. 23, sec, 3, 



