391 
latter 50.6%. The insects, worms, and small Crustacea made up the re- 
maining 5.7%, the greater part of which was composed of the larvae 
of the commoner channel caddis-flies. 
In the shore zones both numbers and weight valuations were con- 
spicuously higher than in the channel, the average poundage in the 
4-7-foot zone being 695 per acre and that in the 1-3-foot zone 391. Con- 
trary to the rule found usually to hold good in the river, the larger Gas- 
tropoda (Viviparidae principally) here showed larger poundages and 
much larger percentages of valuation totals (74 to 91%) both in the 
1-3- and 4-7-foot zones than did the Sphaeriidae. The insects, worms, 
and Crustacea contributed less than one per cent. of the average pound- 
age figures in the 4-7-foot zone. In the hauls taken inside the four-foot 
line, leeches and chironomid larvae were especially abundant, and these 
with a few worms and small Crustacea added, made up over 8% of 
the weight of the average haul. 
Borrom Fauna, 4—-7-Fr. ZONE, PEKIN TO CopPERAS CREEK Dam, 1915 
au : Small 
Viviparidae Insects, 
and : onal worms, Total 
Pleuroceridae Sphaeriidae Crustacea 
Number per sq. yard, 
Average 177.6 104.0 34.4 316.0 
9 collec- 
tions 
Pounds per acre, 
Average 638.0 52.4 bull 695.5 
9 collec- 
tions 
Per cent. of total, : 
(By weight) 91.7% 7.5% 0.8% 
Borrom Fauna, 1—3-r?T. ZoNE, PEKIN To CopPpERAS CREEK Dam, 1915 
29 S Small 
Viviparidae Insects, 
and ; rgal Bo worms, Total 
Pleuroceridae Sphaeriidae Crustacea 
Number per sq. yard, » 
Average 108.4 135.7 116.8 360.9 
Pounds per acre, 
Average 292.4 67.8 31.2 391.4 
Per cent. of total, 
(By weight) 74.7% 17.0% 8.3% 
