289] PROTEOCEPHALIDAE—LA RUE 289 



Fish Haeboring Two or More Proteocephalid Species 



An examination of the complete list of fish Proteocephalids shows 

 that there are fourteen host species which are reported to harbor more 

 than one species of Proteocephalus. The data relating to these cases 

 are presented in the accompanying table which names the hosts, their 

 parasites and the distribution of the latter. A brief study of the table 

 shows that of the fourteen host species ten are accredited with two 

 species of Proteocephalus each, three with three, and one host with four. 

 If from these numbers are deducted the instances of doubtfully identi- 

 fied species and the species inquirenda there follow these results: Five 

 host species each harbor two well described Proteocephalus species while 

 one host harbors three. There are then but six undoubted cases of two 

 or more species of Proteocephalus occurring in the same host species. 



An analysis of these six cases shows that in Lepisosteus platostomus 

 the two parasitic species occur in the same locality, while in the cases 

 of Amia calva, Esox lucius, and Perca fluviatilis the two parasitic species 

 each occur in different localities. Likewise the three species of Proteo- 

 cephalus found in Coregonus maraena occur each in different localities. 

 The distribution of the parasites of Trutta fario is not known. One 

 may conclude that two or more species of Proteocephalus may inhabit 

 the same host species in the same locality or in different localities. The 

 factors which determine this are not here shown. 



Species of Fish which harbor More than One species of Proteocephalus 



