6 Trans. Acad. Sci. of St. Louis. 



Endoparasites. 



Living in the passages or cavities of the body where 

 there is a direct communication with the outer world. 



Living free inside of the body cavity but not in con- 

 nection with the outer world. 



Imbeddpd in the tissues of the host. 



Ectoparasites. 



Cuticolata, living on the skin. 

 Villicolata, living on hairs. 

 Plumicolata, living on feathers. 



Depending upon the duration or time of parasitism. 

 Erratic parasites. 

 Periodical parasites. 

 Nocturnal. 

 Diurnal. 



During a definite stage or stages in the life cycle of the 

 species attacked. 



During the egg stage. 

 During the fetal stage. 

 During Immature stage or stages. 

 During the adult stage. 

 Permanent parasites. 

 Depending upon symbiotic relationship. 



Mutuallsts (where the relationship Is beneficial to both para- 

 sites and host). 

 Commensals (where the relationship Is beneficial to the para- 

 site, and neither beneficial nor injurious to the host). 

 True parasites (where the relationship is beneficial to the 

 parasite and injurious to the host). 

 Depending upon the blood relationship of the parasite to the host. 

 Host or organism affected not related to the parasite. 

 Host or organism affected closely related to the parasite, 

 perhaps belonging to the same family, but not of the same 

 species. 

 Organism affected of the same species as the parasite itself. 

 Host the opposite sex. 

 Host the male. 



Host the female, parasite the male. 

 Host one of the parents, but parasite not fed by special 

 •secreting glands or nourished in the uterus of the 

 female. 



The father the host. 



The mother the host. , 



Host one of the young of the parents. 



