BULLETIN 



ILLINOIS STATE LABORATORY 



NATURAL HISTORY 



URBANA, ILLINOIS, U. S. A. 

 VOL. VIII. ARTICLE I. 



THE PLANKTON OF f THE ILLINOIS RIVER, 1894-1899, WITH 

 INTRODUCTORY NOTES UPON THE HYDROGRAPHY OF THE ILLINOIS 

 RIVER AXD ITS BASIN. PART II. CONSTITUENT ORGANISMS AND 

 THEIR SEASONAL DISTRIBUTION. 



BY 



C. A. KOFOID, PH.D. 



