CONTENTS 



PAGE 



Introduction ^ 391 



Summary 392 



Illinois River above Peoria Lake, La Salle — Chillicothe, 44 miles 393 



Peoria Lake, Chillicothe — P. P. U. Bridge, 20 miles 394 



Illinois River below Peoria, P. P. U. Bridge — Beardstdwn, 71.5 miles 405 



The missing small bottom animals of the 1913-1915 species lists, apparently 

 exterminated some time between 1915 and 1920. Head of Peoria Lake 

 to Beardstown 410 



Small bottom invertebrates of Illinois River and Peoria Lake, La Salle to 



Beardstown, 1923 414 



Pre-1920 bottom species recently missing from Illinois Rivei" and Peoria 



Lake dredge hauls 418 



