120 ILLINOIS BIOLOGICAL MONOGRAPHS [218 



EXPLANATION OF PLATE 



Fio. 36. Junction of Boneyard with Salt Fork canal, looking west. Note high bank on 

 left where mussel shells were found, indicating bottom of bed of Salt Fork stream before the 

 canal was dug. Sludge bank in foreground. September 14, 1920. 



Fig. 37. Salt Fork canal three-fourths of a mile below first iron bridge east of Urbana. 

 December 31, 1919. 



Fig. 38. Farmer's bridge across Salt Fork canal, one-half nule below Brownfield Woods 

 bridge. December 31, 1919. 



