114 ILLINOIS BIOLOGICAL MONOGRAPHS [212 



EXPLANATION OF PLATE 



Fig. 19. Rock bed of Big Vermilion River one mile below Middle Fork. Station 30. 

 October 8, 1920. 



Fig. 20. Sandbar in center of riverbed, several himdred feet below fig. 1. Station 30. 

 Octobers, 1920. 



Fig. 21. Junction of Boneyard with Salt Fork. Boneyard on right above ice. December 

 20, 1919. 



