PRELIMIXAKY SURVEY OF THE ACAXTHOCEPH- 

 ALA FROM FISHES OF THE ILLINOIS RIVER.* 



H. J. Van Cleave^ University of Illinois. 



Life of the Illinois River has received much attention 

 on the part of Professor S. A. Forbes and his colleagues of 

 the State Xatnral History Survey. In his convincing 

 manner Professor Forbes has strongly emphasized the inti- 

 mate relationship between all forms of life in an aquatic 

 habitat. There are few aquatic organisms which do not 

 have some sort of interrelationship with the fishes that live 

 in the same water. Fish as food and food for fish have been 

 two x^hases of this interrelationship of organisms which 

 have received much attention in the past. Little attention 

 has been given to the parasites which attack the fish, 

 though tJiey may directly or indirectly become of consider- 

 able economic importance for the fisheries industry. 



The present paper is based upon intensive examination 

 of the fishes of the Illinois River for Acanthocephala. The 

 entire summer of 1910 was spent at Havana, Illinois, in tlie 

 study of these parasites. Additional examinations were 

 made at various times of the year and some observations 

 were taken at Peoria and at Beardstown. The facts thus 

 brought together constitute the first intensive study of this 

 important group of parasites made for any freshwater 

 habitat in Xorth America.^ 



The Acanthocephala comprise a group of worms which 

 represent the development of the parasitic habit to the 

 fullest extent. Worms of this group have become so pro- 

 foundly modified in structure that the body consists of a 

 sac for containing the reproductive organs and a special 

 organ of attachment called the proboscis. Xo special sense 

 organs, no locomotor structures, and no special organs for 



♦Contributions from the Laboratory of the ruivorsity of Illinois. Xo. l."2. 

 * In the interval between the reading and the publishing of this preliminary 

 ey the full results of the investigation have been published in the Bulletin 

 <jj. ihe Illinois Natural History Survey. Vol. XIII. Art. VIII. (191fl>. In the 

 meantime the results of nvestgatons n other localtes have also been publshed. 



151 



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 of th 



