14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



have seen this parasite think it may be a fungus; mycologists have 

 shown a preference for regarding it as a protozoan. Nothing else is 

 known of it. 



Food Habits 



The crayfish. — No concentrated effort has been made to determine 

 what the crayfishes of the area feed upon, but on the basis of a few 

 observations it seems that the chief item of their diet is decaying 

 plant fragments. Both in the laboratory and in the streams, the 

 crayfish seem readily to accept whatever animal material becomes 

 available; occasional individuals have been observed feeding on fish 

 and insect larvae and not a few on crayfish of the same or different 

 species. In the laboratory, they do not scorn fresh plant material 

 such as lettuce. Crayfishes are as nearly omnivorous as any animals 

 ever observed by us. 



The ostracods. — Marshall (1903, p. 118), who described the 

 first known member of the family, Entocythere cambaria, was of the 

 opinion that this ostracod lived in the gill chamber of the crayfish 

 host, where it fed on the readily accessible blood flowing through 

 the branchiae. In contrast, Rioja (1940a, p. 593) indicated in con- 

 nection with his description of E. heterodonta (— Ankylocyihere hetero- 

 donta) that this ostracod is rarely found in the gill chamber of the 

 host and that he considered the members of this genus to be "simple 

 epizoario," taking issue with Marshall's belief that E. cambaria is a 

 parasite. Rioja (1940b, p. 58) reiterated the opinion that An. hetero- 

 donta is an epizootic commensal. In 1941 (p. 194) Rioja, in dis- 

 cussing the same species, indicated that he had observed the feeding 

 process, which involved the use of the terminal claws of the feet 

 and the apical claws of the second antenna in passing "detritus 

 diversos" to the mouth. Hoff (1942, p. 64) also questioned the fact 

 that Marshall's species was parasitic, indicating that Marshall's 

 deduction "based on the belief that the homogeneous mass of material 

 in the intestine of the ostracod is the blood of the host ... is not 

 valid proof . . . since a homogeneous food mass is found as well in 

 many free-living ostracods." He summarized the situation as follows : 



That the Entocythere species do feed on material in the water is evidenced by 

 the finding of diatoms and other particulate organic materials in the gut. That 

 the organisms are not strictly parasitic is also shown by the fact that they often 

 for some reason leave the host. Individuals have been found by the writer in 

 the water of crayfish burrows and by Klie (1931) in Indiana cave waters. All of 

 the Entocythere species are probably commensal, but at the very most, if para- 

 sites at all, are only facultative. 



Our observations support Hoff's conclusions and those of Rioja: 

 in living animals both the mandibles and maxillae with their branchial 

 plates seem constantly to be in motion receiving finely divided particles 



