Occasional Papers of the Museum of Zoology 7 



doloniicn. The number in a single host individual varied from 

 one to five as a maximum. 



The minute size of the representatives of B. thccatiis found 

 in this species is notev^orthy in that it gives a probable clue to 

 a periodicity in the life cycle of this species. All of the speci- 

 mens of M. sahnoidcs in this collection were examined about 

 three weeks earlier than any of those of M. dolomicn. Since 

 individuals of B. thecatus from the last named host were much 

 the larger, many of them fully mature, and much more num- 

 erous than in M. sahnoidcs, it seems that evidence is here pre- 

 sented of a periodicity in life cycle of the parasite. Since hosts 

 taken the second week in July carried but few immature par- 

 asites while those taken the first week in August were heavily 

 infested with sexually mature parasites there is probably a sea- 

 son of the year when E. thecatus is absent from the digestive 

 tract of its normal definitive host. This is borne out by the 

 evidence of an infestation period beginning in June or early 

 July for the locality under consideration. 



Auibloplites rupestris (Rafinesque). Rock Bass. 



Specimens examined : 10. Infested with Acanthocephala : 7. 



Analysis of Infestation 



No. of 

 Species represented in individual host instances 



E. thecatus Linton, only 5 



P. bulbocoUi Linkins, only ' I 



E. thecatus 



P. huWocolli 



E. thecatus is the most characteristic acanthocephalan of 

 this host. Infestations were extremely light, single specimens 

 being encountered frequently. The maximum infestation for 

 an individual of this species comprised eighteen individuals of 

 E. thecatus and a single one of P. bulbocoUi. One host car- 



