404 
Botrom Fauna, 1915, 1—3—roor Zone, Foot or Granp ISLAND TO BROWNING 
(9 MILES) 
sd 3 Small 
Viviparidae Insects, 
and — ‘ Gaaee one worms, Total 
Pleuroceridae Sphaeriidae Crustacea . 
Number per sq. yard, 
Average 327.4 186.2 26.1 539.7 
4 coll.’s 
Pounds per acre, 
Average 1,516.0 93.1 4.3 1,613.4 
4 coll.’s 
Per cent. of total, | 
(By weight) 93.9% 5.7% 0.2% 
(f) Lacrance Dam To GraFton (77.5 Mires) 
Hydrography—tThe average velocity in the 77.5 mile stretch of 
channel between the Lagrange dam and the mouth of the river in March, 
1903, at a gage of about 18 feet, Peoria, (172.30° feet per minute), was 
more than three times that between Chillicothe and Peoria at the same 
time (51.94 ft. per minute); more’than twice that between Copperas 
Creek dam and Havana (83.81 ft.) ; and exceeded that of any other sec- 
tion of channel below Chillicothe except the 9 miles between Peoria and 
Pekin. The average decline in elevation of water surface at the 1901 
low gages between Lagrange and the dam at Kampsville (0.85 inches per 
mile) was more than three times the average through Peoria Lake; and 
DECLINE IN ELEVATION OF LOW-WATER SURFACE, 1901; AND FrLoop VELocrTy 
Z Flood velocity (av. 
Interval AY. Slope feet per minute), 
Reach = inches 
miles 3 gage, 18 feet, 
ee Peoria* 
Lagrange dam (below) to Grafton 77.5 aba 172.30 
Lagrange dam (below) to Kampsville 
dam (above) 46.1 0.85 164.24 
Lagrange dam (below) to Florence| 21.9 1.26 146.92 
Florence to Kampsville dam (above)| 24.2 0.49 183.85 
Kampsville dam (below) to Grafton) 31.4 2.44 186.91 
*Van Ornum float tests, March, 1903. 
