■M4 



Diptera. Cliironomidae : Cliirotwinus sp., \z.rvat. 



Sludge-worms, Tubificidae, very abundant. 



Adults of the damsel-fly, Hctacrina amcricana (Fabr.) were very 

 abundant along the stream but no naiades could be found. 



Station 4. — Salt Fork, one-fourth mile below the outlet of the Cham- 

 paign sewer, July 30. Stream wide and fast-flowing, but the bottom 

 black and with a foul odor. 



Hemiptera. Gerridae : Gerris marginatus Say, one adult. 



Beneath the surface, the only life found was a sparse number of 

 sludge-worms. The damsel-fly Ischnura verticalis (Say) was common 

 but no naiades were to be found. 



Station 5. — Salt Fork at the first iron bridge (between the Cham- 

 paign sewer outlet and the Augurville bridge), July 20. The water runs 

 rapidly and the upper surfaces of the rocks appear rather clean, though 

 blackened. On lifting the rubble, however, a mass of inky black sludge 

 is loosened that would preclude any except the most septic organisms. 

 No insects occurred and no other life except a few specimens of sludge- 

 worms. 



Station 6. — The Au.gin'ville or Brownfield Bridge. July 20. The 

 stream here is broken into riffles but this does not suffice to support a 

 fauna any more varied than at the last station. No insects occur and 

 only a few sludge-worms. Adults of the following Odonata were noted : 

 Plathcrnis lydia (Dru.) and Argia violacca (Hagen). These presumably 

 come from ponds or backwaters with clean water, as no naiades were 

 taken at this station. 



Station 7. — Third bridge over the Salt Fork, July 20. Conditions 

 quite as at Station 6. No insects were to be found and only a few sludge- 

 worms. 



Station 8. — Cottonwood Bridge, July 20. The stream here was very 

 low (July 20) and extremely black and polluted. Odor bad. No life 

 of any sort 



Station 0, — Mayview Bridge, July 20. Conditions here about as at 

 Station 8. The only insects in the water were large swarms of whirligig 

 beetles, Diucutcs auicricanus Say. A careful search was made for their 

 larvae but these do not occur and the swarms must migrate from purer 

 water. Adults of Odonata, Plathemis lydia (Dru.) and Isclniura verti- 

 calis (Say) were noted, but not ovipositing. 



Station 10. — The Salt Fork. 100 yards above (west of) the mouth 

 of Spoon River, near St. Joseph, July 23. Water low (6 to ^ inches) 

 but the sandy bottom very clear, not polluted heavih' as in Stations up 

 to nine. There is no apparent bad odor, but the people living here state 

 that later in the season at times the odor is very bad. Frogs and turtles 



