156 ILLINOIS ACADEMY OF SCIENCE 



But two species are restricted to a single species of host. 

 Other species occur in widely separated Orders of fish. 



E. thecatus, the most common species, was found in 

 fourteen species of fish representing six Orders. 



Two genera, Tanaorhamphus and Gracilisentis, known 

 only from fishes of this stream, are restricted to a single 

 species of host ; namely, Dorosoma cepedianum. 



A number of new host records are listed. 



Four species are recorded for the first time from the 

 State of Illinois. 



