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 Dlinois 
No. 22 
