THE MOLLUSCAN FAUNA OF THE 



BIG VERMILION RIVER, 



ILLINOIS 



With Special Reference to its Modification as the Result of 

 Pollution by Sewage and Manufacturing Wastes 



WITH FIFTEEN PLATES AND ELEVEN TABLES 



BY 



FRANK COLLINS BAKER 



Curator of the Museum of Natural History 



University of Illinois 



Contributions from the 



Museum of Natural History of the University of Illinois 



No. 22 



