2 University of Michigan 



made upon the Acanthocephala of a habitat in North America 

 similar to the one under consideration it seems desirable to 

 present the results of this investigation. A number of new 

 hosts have been discovered. These with biological data con- 

 cerning a number of species, including a number of important 

 negative findings, will add to the available data concerning this 

 important group of fish parasites. In connection with the 

 presentation of negative records it must be remembered 

 that the period over which the examinations extended was 

 restricted to the months of July and August. Thus there is a 

 possibility that fishes not parasitized with Acanthocephala dur- 

 ing these two months might harbor them at other seasons of 

 the year. J^uch periodicity has been shown by the writer 

 (1916) to occur in varying degrees in certain freshwater 

 species of Acanthocephala. 



Reighard (1915) in his reconnaissance of the fishes of 

 Douglas Lake has recorded twenty-two species of fish from this 

 region. La Rue's examinations for parasites include data for 

 sixteen of these species. Of the six species not represented 

 in his records of examinations five are of rare occurrence in 

 Douglas Lake, or at least have been infrequently taken in col- 

 lections. These rare species of which no exanfinations are 

 available are: Notropis cayiiga Meek, Ethcostoma iozvae Jor- 

 dan and Aleek, Cottiis ictalops (Rafinesque), Lota maculosa 

 (LeSueur). and Umbra liiiii (Kirtland). The last of these ac- 

 cording to Reighard has never been taken in Douglas Lake it- 

 self. Consequently it is apparent that records containing data 

 for sixteen of the species make possible an unusually com- 

 prehensive survey of the Acanthocephala infesting the fishes 

 of the vicinity. 



Eight of the sixteen species of fish included in this investiga- 

 tion were found to harbor Acanthocephala. The percentages 



