490 
4 CoLLections, 1- To 3-rT. Zone, Aue. 6, 1915 
Foot or GRAND ISLAND TO BROWNING 
(9-MILE SECTION OF NARROW, DEEP CHANNEL) 
Number per square yard| Pounds per acre 
Campeloma subsolidum 46.2 138.6 
Lioplax subcarinatus 2.5 7.5 
327.4 1516.0 
Vivipara contectoides 272.5 1362.5 
Pleurocera sp. 6.2 7.4 
Musculium transversum 186.2 186.2 93.1 93.1 
Hydropsyche larvae 3.7 0.7 
Chironomid larvae (small spp.) 3.7 26.1 0.5 4.3 
Leeches (small spp.) 18.7 3.1 
Total 539.7 1613.4 
6. LAGRANGE DAm TO GRAFTON 
14 COLLECTIONS (AVERAGED), Auc. 11, 1915 
LAGRANGE DAM TO FLORENCE 
Number per square yard| Pounds per acre 
Four channel collections 0.25 trace 
Two collections, 4- to 7- ft. zone 
Musculium transversum 115. 57.5 
Eight collections, 1- to 3-ft. zone 
Musculium transversum 15.6 7.8 
16.3 9.2 
Young Unionidae 0.7 1.4 
Small oligochaetes 1.2 trace 
‘ 2.2 0.9 
Hexagenia, etc. (nymphs) 1.0 0.9, 
Total 18.5 10.1 
