84 



ILUNOIS BIOLOGICAL MONOGRAPHS 



[182 



green putrescent matter, measuring in size from a peanut to a dish pan. 

 Some of these masses are brownish, where the algae and Protozoa have not 

 completely taken possession of them. 



A large amount of oily scum may be observed on the surface and 

 when disturbed the bottom emits quantities of oily matter, as is the case 

 higher up the stream. On exposed bars and along shore the algae and 

 putrescent matter have dried and caked, forming a pavement-like layer. 

 The water is clearer here than in the portion of the stream previously 

 examined, but no clean water life could be found; mussels, crayfeh, and 

 insects were entirely absent. 



Samples of the bottom from the stream about 300 feet east of the 

 Mayview road bridge, about six miles below the Champaign outlet were 

 examined. The following life was present: 



Blue-green algae 



Pediaslmm simplex, rare. 

 PbortittdUtm irtundalum, common. 



Diat(»ns 

 Nawicula salinarum, abundanL 

 Praplaria capudna, abundant. 



Animals 



Ciliata, minute, abundant. 



Colpodium, several. 



Euglena genictdaia, very abimdant. 



Limnodrilus, common. 



Nematode worms, minute, abundant. 



About a mile and a half below this locality additional samples were 

 taken for examination. Conditions are similar but the water is not as 

 clear, holding more sediment in suspension. 



Blue-green algae 



Pedia^ntm simplex, rare. 

 Pkormidiiim immdatum, abundant. 



Diatoms 

 FragHaria capucina, abundant. 



Animals 



Ciliata, minute, abimdant. 

 Paramoedum, severaL 

 Euglema gemculata, abundanL 

 limnodrilus, about a dozen. 

 Nematode worms, minute, many. 



At the last north and south farmer's bridge, the canal makes a wide 

 sweep, in a southeasterly direction (Fig. 43) leaving the old stream bed 

 to the west of the new channel, in the form of an *ox-bow' almost half 

 a mile in length, which, during the greater part of the year, forms a large 

 elongated pond, that drains into Salt Fork canal by me^fos of a small outlet 

 at the south end which turns abruptly northeastward as it empties into the 

 canaL At the time examined, the bed of this old stream was almost dry, 

 following a period of very dry weather, and the fauna had retired to several 

 small, shallow, muddy pools which remained in the deeper parts of the 

 stream bed. An examination of these pools disclosed a number of bull- 

 heads (Ameiurus melas)^ many dragonfly larvae {Libellula pulchdla)^ 

 and a few mollusks {Planorbis trivolvis, Physa gyrina, and Musculium 

 transversum). 



