61 



STUDIES 



ON THE 



AQUATIC LIFE OF ILLINOIS, L 



INTRODUCTION. 



The investigation of which the present paper is intended to set 

 forth in a general way a few of the results, has for its purpose an 

 exhibit of the animal life of the waters of Illinois as related to 

 fish culture primarily, but also and finally in relation to nature at 

 large. To this end studies have been carried forward on the kinds 

 and comparative abundance of animals of every descrij^tion occur- 

 ring in the localities and situations selected for examination, at 

 different seasons of the year, and under various conditions as to 

 food, temperature, stage of water, and the like, and as affected by 

 the general system of relations obtaining among the organisms 

 themselves. In reporting these studies we shall not confine our- 

 selves to annotated lists, but expect to enter into the fullest prof- 

 itable detail with regard to habits, methods of association, and 

 relations of mutual benefit, rivalry, or injury, and to show how 

 and to what extent these habits and interactions vary from time 

 to time with changes of condition. 



The present contribution is based on collections and studies made 

 in the summer of 1888 from the State Laboratory of Natural His- 

 tory at Champaign, with its apparatus and equipment and princi- 

 pally at its expense; but they have been greatly aided and facili- 

 tated by the Illinois State Fish Commission, by whom room, 

 workmen, boats, and field assistance were freely furnished for 



