. Bulletin. Natural history; Natural history. 67 Not only in Thompson, Dogfish, and Liverpool lakes in 1930, but in Quiver Lake also in its muddy part, we found nothing at all surviving out of a list of some ten or twelve families of minor insects and miscel- laneous small bottom-animals other than the groups already passed in re- view that were common in all of these lakes in 1914—1915. Though this item of loss in the lakes near Havana has been greater since 1915 than in the river just above Havana, the decrease in poundage therein in com- parison to totals of all small bottom-animals has not
. Bulletin. Natural history; Natural history. 67 Not only in Thompson, Dogfish, and Liverpool lakes in 1930, but in Quiver Lake also in its muddy part, we found nothing at all surviving out of a list of some ten or twelve families of minor insects and miscel- laneous small bottom-animals other than the groups already passed in re- view that were common in all of these lakes in 1914—1915. Though this item of loss in the lakes near Havana has been greater since 1915 than in the river just above Havana, the decrease in poundage therein in com- parison to totals of all small bottom-animals has not been very large, the figures that follow showing that at the best the total weight of "other in- sects, etc.," in the bottom muds of these lakes in 1914—1915, did not run to twenty pounds per acre. In the Quiver Lake "channel" and in the sand and mud toward the beach side our collections showed leeches, Bryozoa, larvae of caddis-flies, and nymphs of Odonata in good variety and number, the "channel" average in 1920 (32 pounds per acre) being larger than in 1915. "Other Insects," Worms, Crustacea, ktc. of the Bottom Muds. xiakes north op havana, 1914—15 and 1920 I. Mud bottom, 2 to 6 feet. 11. Sandy or sand and mud bottom Quiver Lake "channel" * 26 36 3 32 Quiver Lake, sandy shore, east side Not separately counted 15 Not separately valued 8 * Figures in 1914—1915 columns are for year 1915. t Figures in 1914—1915 columns are for year 1914. The decrease in average valuation of all small bottom-animals in the four lakes since 1915, with the sandy portions of Quiver Lake omitted, has been in ratios quite similar to those of average decline in the period in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illinois. Natural History Survey Division. Urbana,
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