THE TOPOGRAPHY AND HYDROGRAPHY OF ILLIXOIS xliii 



south we find a series of open places locall}^ known as ''ponds." 

 The warm still waters are turbid in places from the movements 

 of fish, and at times we see the compact schools of young dogfish 

 {Amia calva) and, if we are late enough in the season, the myriads 

 of young black, tadpole-like catfish {Aynemrus), likewise in 

 schools, while young carp {Cyprinus carpio) are everywhere. 

 The new vegetation is already springing from the decaying and 

 matted stems of the preceding summer. Turning back towards 

 the river we pass through the heavy timber where the still brown 

 water, cool and clear, overlies the decaying leaves and vegeta- 

 tion of last season's growth, now coated with the flood deposits 

 of the winter. Emerging again upon the river channel, we may 

 find a turbid yellow flood pouring out from Spoon River, bring- 

 ing down its load of drift and earth, and marking its course down 

 the stream as far as the eye can see. 



"Contrast with the extent and variety of conditions at flood 

 the limitations placed upon the stream at low water. Instead of 

 an unbroken expanse of four or more miles we find now a 

 stream only 500 feet in width, while the adjacent territory is dry 

 land save where the sloughs, marshes, and lakes remain as res- 

 ervoirs. Quiver Lake is now much reduced in width, and it may 

 be choked with vegetation except in a narrow channel where the 

 clear water shows little or no current. A half mile below we 

 find the river water rushing in a narrow ''cut-off" across the 

 ridge of black alluvium into the lower end of the lake. The 

 wooded banks which separate the river from Quiver and Seeb's 

 lakes are now crowded with a rank growth of weeds and vines. 

 The latter "lake" is reduced to a shallow stagnant arm of the 

 river, whose warm turbid waters are foul with dead mollusks, and 

 whose reeking mud-flats beneath the August sun shine green and 

 red with a scum of Euglena. As we pick our way through the 

 tangle of rank vegetation we come upon Flag Lake, now a sea of 

 rushes. The discharge from this marsh to the river ceased in the 

 early summer, and its margins are even now dr3% with gaping 

 cracks. Beyond the marsh we pass to the shore of Thompson's 

 Lake to find its southern end choked with vegetation, though the 

 greater part to the north is open water. The woodland and 

 open ground to the south are now pastures and fields of waving 

 corn. The only outlet to this large body of water, now somewhat 

 reduced in area but warm, turbid, and rich in plankton, is a 

 tortuous slough six miles to the north. The discharge, how- 



