OH 



f BULLETIN 



V l ^ OF THE 



ILLINOIS STATE LABORATORY 



OF 



NATURAL HISTORY 



Urbana, Illinois, U. S. A. 



Vol. VI. NOVEMBER, 1903 . Article II. 



THE PLANKTON OF THE ILLINOIS RIVER, 1 894- 1 899, WITH IN- 

 TRODUCTORY NOTES UPON THE HYDROGRAPHY OF THE ILLINOIS 

 RIVER AND ITS BASIN. PART I. QUANTITATIVE INVESTIGATIONS AND 

 GENERAL RESULTS. 



BY 



C A. KOFOID, PH.D. 



