8 University of Michigan 



ried a single gravid female of P. bulbocolli attached to the 

 wall of the intestine. 



A cyst in the stomach wall of one host individual yielded a 

 single specimen of what is apparently E. thccatus. 



Percina caprodes (Rafinesque). Log-perch. 

 Specimens examined: 13. Infested with .\canthocephala : 10. 



Analysis of Infestation 



No. of 

 Species represented in individual host instances 



E. tliccatus Linton, only 6 



P. bulbocolli Linkins, only i 



E. thccatus 



P. bulbocolli ' ^ 



This species apparently serves E. thccatus both as intermed- 

 iate and as definite host. Numerous cysts bearing E. thccatus 

 were encountered, especially in the mesentery. All of the in- 

 testinal forms encountered were immature. However, the 

 examinations were all made early in July. It has been point- 

 ed out previously that E. thccatus is apparently entering the 

 infesting stage at about this time. It is consequently imposs- 

 ible to determine whether this host serves normally as a defin- 

 itive host or whether the parasites were taken into the digest- 

 ive tract and had not yet found time to encyst as would be the 

 case if this species served only as intermediate host. 



Pomphorhynchus bulbocolli is a normal intestinal parasite 

 of this host, though it also is found in cysts. One specimen 

 bore five normal adults attached to the intestine wall. 



Reig^iard (191 5) has referred to the association of the log- 

 perch and suckers at the breeding season. It is possible that 

 the encysted larvae in the bodies of the log-perch may be re- 

 sponsible to some extent for the infestations of Pompho- 

 rhynchus and of Echinorhynchus found in the sucker. The 

 rare occurrence of E. thccatus in the sucker would indicate 



