401 
Bottom Fauna—A total of 58 bottom collections, at 9 stations, in 
cross-section, were taken in 1915 between Havana and the Lagrange dam, 
distributed between the channel and the shore zones and from north to 
south as shown in the following table. 
CoLLecTIoNS, HAvANA TO LAGRANGE Dam, 1915 
Miles 
above Station Channel | 4—7-ft. zone | 1—3-ft. zone 
Grafton 
1. Havana to foot Grand Island 
(13.8 miles) 
114.7 Opposite foot Matanzas Lake 3 | 2 
500 yards above head of Grand 
113.7 Island Nepaee =| 2 8 
2.Foot Grand Island to Brown-| 
ing (9.0 miles) 
101.0 Opposite foot of Stewart Lake 1 4 2 
97.0 1/4 mile below Browning 1 6 2 
] 
3. Browning to Lagrange dam) 
(19.7 miles) 
89.5 1 mile above Beardstown 1 6 2 
84.0 Brigg’s Landing my 
83.2 Reich’s Landing 2 
80.3 Lagrange Landing } 2 
77.7 200 yards above dam 1 2 6 
Total 16 22 20 
With reference to the bottom fauna this reach of 42.5 miles may 
be described as a whole as a section of exceedingly poor channel, bor- 
dered on either side by a comparatively rich shore fauna. The average 
channel poundages of bottom animals taken in 1915 between Havana and 
the dam at Lagrange was only 22 lbs. per acre, or not much more than 
one fifteenth of average channel valuation between Chillicothe and the © 
foot of Peoria Lake (345 Ibs.), and less than one two-hundredths of the 
average between Liverpool and Havana (5,180 Ibs.). While the channel 
fauna was about equally poor throughout the 42.5 miles in 1915, the 
shore fauna (bottom animals within the 7-foot line) was distinctly rich- 
est in the central deeper section of river above the mouth of Sangamon 
River, where the 4-7-toot zone showed figures (365.6 lbs. per acre) about 
30% over the average of the 4-7-foot zone for the 42.5 miles, and 
the 1-3-foot zone a rating (1,613.4 Ibs. per acre) nearly four times the 
42-mile average, or more in fact than was found anywhere else at that 
depth between Chillicothe and Grafton. The greater part of the weight 
of the average collections in the 42 miles, whether from channel or shore 
zones, consisted of the larger snails (Viviparidae). Though larvae of 
caddis-flies and nymphs of May-flies were relatively commoner than 
above Havana, they were not numerous enough anywhere to contribute 
