Occasional Papers of the Musemn of Zoology 3 



of infestation and the number of species of parasites found 

 varied broadly in the different hosts. In the following section 

 an analysis of the acanthocephalan infestation is given for 

 each host species. 



List oi? Species Ineested with Acantiiocepiiaea 

 Catosfoiniis couiuicrsonii (Lacepede). Common Sucker. 

 Specimens examined : 15. Infested with Acanthocephala: 10. 



Analysis of Infestation 



No. of 

 Species represented in individual host instances 



Pomplwrhynchus hulbocolli Linkins, only 4 



Octospinifcr macilcntus VanCleave, only I 



Neoccliinorhvnchus crassus VanCleave 



Pomphorhyncluts hulbocolli Linkins ^ 

 Poinp/iorhynclnis hulbocolli Linkins ) 

 Echinorliynclius thccattis Linton i 



Pomplwrhynchus hulbocolli Linkins ] 



N cocchinorhynchus crassus VanCleave > . . 2 



Octospinifcr luacilenfus VanCleave ' j 



Though four species of Acanthocephala were found in this 

 host they were so distributed among individuals that no host 

 specimen harbored representatives of more than three species. 

 A few instances of simple infestation were recorded. Four in- 

 dividuals bore Pomphorhyncluts hulbocolli only, while one 

 carried a simple infestation of Octospinifcr macilcntus. P. 

 hulbocolli was present in nine of the ten infested individuals. 

 One specimen examined Aug. 5, 1912, harbored nearly three 

 hundred fully matured parasites of this species, while other 

 individuals collected at approximately the same time revealed 

 but a very slight infestation. No satisfactory explanation has 

 been found for this great variability in degree of infestation 

 within the same host species from the same locality. It may 

 be due to individual dift'erences in food habits of the hosts or 



