533 



water forms were 138 to the cubic centimeter at Hennepin, 744 at 

 Chillicothe, and 154 at Marseilles, as compared with 193 at Morris. 

 Oxygen ratios were a little lower in July, August, and September 

 than at Starved Rock, and somewhat higher in October and No- 

 vember. 



As this was the first station at which the life of the river may 

 be said to have found virtually normal conditions, some further 

 testimony to that effect may be drawn from our collections of mus- 

 sels and fishes. Seventeen species of mussels were collected alive, 

 and five others were represented only by dead shells. Of these 

 Lampsilis fallaciosa, Quadrula plicata, Symphynota complanata, Ano- 

 donta corpulcnta, and Quadrula heros were the most abundant, in 

 the order named, and, with a single exception, all the specimens of 

 these species were alive. The nvmiber of living shells as com- 

 pared with dead ones is in marked contrast to the conditions found 

 above. The following is a complete list. 



Hennepin, 1912 



