NO. 15 



ARTHROPOD HOSTS OF HELMINTHS — HALL 



67 



Acanthocephala 



No. of host 

 Intermediate spp. 



host group involved 



Crustacea : 



Amphipoda 4 



Isopoda I 



Decapoda i 



Insecta: 



Coleoptera 11 



Neuroptera 2 



Orthoptera 2 



No. of parasite spp. 



with known hosts 



for adults 



No. of parasite 



spp. reported as 



larvae without 



known hosts 



for adults 



Among the Crustacea, the Amphipoda are of special significance as 

 hosts for acanthocephalids of aquatic animals, so far as the life his- 

 tories of such worms are known. The only other crustaceans involved 

 are Isopoda and Decapoda. 



Among the Insecta, the Coleoptera are of major importance as 

 carriers of acanthocephalids with known life histories. The only other 

 insects involved are Neuroptera and Orthoptera. 



If we take the outstanding groups of intermediate hosts for each 

 order of parasites, we have the following: 



For Cestoda : Copepoda and Ostracoda ; Coleoptera. 



For Trematoda : Decapoda ; Diptera, Trichoptera, Odonata, and Ephemerida. 



For Nematoda : Copepoda ; Diptera and Coleoptera. 



For Acanthocephala : Amphipoda ; Coleoptera. 



Among the insects, the importance of the Coleoptera is indicated 

 by the fact that this group is of decided significance for Cestoda, 

 Nematoda, and Acanthocephala. The Diptera are important as car- 

 riers of Trematoda and Nematoda. The Trichoptera, Odonata, and 

 Ephemerida only figure as outstandingly important for Trematoda. 



Among the crustaceans, the Copepoda are the major group as hosts 

 for both Cestoda and Nematoda. The Ostracoda are only known to 

 be important as hosts for Cestoda, the Decapoda as hosts for Trema- 

 toda, and the Amphipoda as hosts for Acanthocephala. 



The following table is inserted to give a rapid check on the known 

 occurrence in the dififerent arthropod hosts of parasites of the groups 

 involved in this paper. If an arthropod group is known to contain 

 intermediate hosts for the worm groups involved, an X is placed under 

 the worm group and opposite the host group. If there are no such 

 hosts known, an O is placed in the corresponding position. 



