The examination of 63 bottom samples, collected in Lake Huron in 1952 and 1956, revealed that Pontoporeia affinis was the dominant organism in both deep and shallow water. The next most abundant organisms in deep water were oligochaetes, fingernail clams, and midge larvae. Midge larvae were more numerous than either oligochaetes or fingernail clams in shallow water. The nmnber of organisms per squ