NO, 15 ARTHROPOD HOSTS OF HELMINTHS HALL 69 



Taking the major host groups, the Crustacea, Insecta, Myriapoda, 

 and Arachnida, as a whole and the four worm groups as a whole, we 

 may make the following summary : 



There are 48 species in the Cestoda which have arthropods as 

 intermediate hosts and for which we know the primary hosts; there 

 are 22 larval forms in addition for which the primary hosts are not 

 known. 



There are 37 species in the Trematoda which have arthropods as 

 intermediate hosts and for which we know the primary hosts ; there are 

 2^ larval forms in addition for which the primary hosts are not known. 



There are 49 species in the Nematoda which have arthropods as 

 intermediate hosts and for which we know the primary hosts ; there 

 are 12 larval forms in addition for which the primary hosts are un- 

 known. 



There are 9 species in the Acanthocephala which have arthropods 

 as intermediate hosts and for which we know the primary hosts. 



There are altogether 143 species of worms parasitic in vertebrates 

 which have arthropods as intermediate hosts and for which the pri- 

 mary hosts are known ; there are 61 larval forms in addition for which 

 the primary host is unknown. 



In the Crustacea there are 49 species which serve as intermediate 

 hosts for Cestoda, 22 for Trematoda, 12 for Nematoda, and none for 

 Acanthocephala. 



In the Insecta there are 25 species which serve as intermediate 

 hosts for Cestoda, 46 for Trematoda, 122 for Nematoda, and 15 for 

 Acanthocephala. 



In the Myriapoda there are 2 species which serve as intermediate 

 hosts for Cestoda, and none for Trematoda, Nematoda, or Acantho- 

 cephala so far as we know at present. 



In the Arachnida there are 6 species which serve as intermediate 

 hosts for Nematoda, and none for Cestoda, Trematoda, or Acantho- 

 cephala so far as we know at present. 



The Insecta are far in the lead as regards number of species known 

 to serve as intermediate hosts for parasitic worms, as there are 186 

 species of insects, 'JJ species of crustaceans, 6 species of arachnids, 

 and only 2 species of myriapods included in these lists of intermediate 

 hosts. The total number of arthropod species listed here as inter- 

 mediate hosts for the worm groups involved is 271. 



CONCLUSION 



It should be reiterated that one must not draw too sweeping con- 

 clusions in regard to the importance of host groups or in regard to 



