534 



The following fishes were taken September 6 and 13 from the 

 river in the vicinity of Hennepin, by seven hauls of a 30-yard min- 

 now seine, 15 hauls with a 200-yard seine with an inch mesh, and 

 a single haul made for us by a fisherman with a common river-seine. 



Hennepin, ipi2 



Short-nosed gar, i Speckled bullhead {Ameiunts nebido- 



Dogfish, 3 sus), I. 



Common sucker, i. Black bullhead, i. 



European carp, 174. Black crappie (Pouioxis sparoides), i. 



Shiner, many. Warmouth {Chccnohryttiis gulosiis), i. 



Golden shiner, many. Blue-gill sunfish, 3. 



The weather was very hot when the larger seines were used, 

 ranging above 90° F. every day, with the water at 79°, and the 

 fishing was unusually poor. 



Henry to Chillicothe 



As this is the final section of our series, a fairly full description 

 of conditions found and collections made will be desirable for com- 

 parison. Even under the midsummer conditions of July and August, 

 191 1, with the river temperatures at 73° to 80° F., the water had 

 a distinct greenish cast, without odor; and mud taken from the bot- 

 tom had a "good fresh smell." In March, 1913, however, the sludge 

 from a deposit two feet deep a hundred yards above the Henry dam 

 had a distinct sewage odor, and was destitute of animal life, except 

 for one small leech, in nine two-quarts samples collected. The cooler 

 temperature of the water (41° F.) delayed decomposition, and the 

 comparatively strong current of the stream at the high water of 

 this visit (10 feet at the upper gage) was doubtless rolling the bot- 

 tom sediments more rapidly down the stream than in the lower stages 

 at which our earlier observations were made. Practically the same 

 may be said of the condition of the bottom mud from the main 

 channel at Chillicothe at this time. The river was, however, still 

 far below a normal unpolluted stream in oxygen ratios, and con- 

 tained much more carbon dioxide. A number of tests of midstream' 

 samples made August 3 and August 29, gave us 2.33 parts per mil- 

 lion of oxygen as a minimum and 4.59 as a maximum, with an aver- 

 age of 3.76 for nine determinations. Carbon dioxide ratios for 

 this period ranged from 4.9 to 6.9 parts per million. 



A heavy flooding rain which fell August 10 had the effect to 



