American Fisheries Society. 27 



GQl (54^1 _ _^ ff^°_ _ ,,_ _7^1 7ff° ^0"" 



This Figure sliows ihe temperature of the water of Lake Mendota on August 12, iSgti. 

 The vertical lines indicate temperature and the horizontal lines indicate depth in meters. For 

 g^eneral purposes 3 meters may be reckoned as 10 feet. The heavy line going obliquely across 

 the diagram indicates the temperature at the different depths, being 79° and a fraction at the 

 surface, about 78° at 6 meters (20 feet), 65° at 10 meters, etc. On this date there were only 

 5,500 Crustacea per square meter of surface between 10 and 18 meters, 2^,000 between 9 and 10 

 meters, and 66,000 between S and 9 meters. 



