n^io 



Bulletin 



OF THE 



Illinois State Laboratory 



Olf 



Natural History 



Urbana, Illinois, U. S. A. 



STBPHE^N A. FORBES, Ph.D., LL^.D., 

 Director 



Vol. IX. June, 1913 Article X. 



STUDIES ON THE BIOLOGY OP THE 

 UPPER ILLINOIS RIVER 



BY 



Stephen A. Forbes and R. E. Richardson, A.M. 



