72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Of these four methods of work the first two give positive proof of the life 

 history when the experiments are successful ; the third gives a probability to the 

 statements, but not a proof ; the less said about the fourth method the better. 



In this later epoch it is advisable to establish a life history by both 

 of the first methods, not ignoring the third, if adequate evidence is 

 desired. Raising Diphyllohothr'mm latum in dogs by feeding plerocer- 

 coids from fish did not show that a copepod was the first host ; failure 

 to infect fish with the tapeworm eggs necessitated further search and 

 so led to the discovery of the copepod host. Another thing deserves 

 emphasis : Finding that one arthropod is an intermediate host does 

 not settle the problem of a life history of a worm. The worm may 

 have a score of intermediate hosts, and the most important one may 

 not be an arthropod. 



ADDENDUM 



Since the foregoing was written the following records have come 

 to hand and are given here without discussion : 



LIST BY PARASITES 

 (Crust. ^ Crustacea) 



CESTODA 

 CESTODARIA 



Amphilina foliacca — Corophiu»i citrvispinum ; Crust.; Amphipoda 



Dikerogammariis haemobaphes ; Crust. ; Amphipoda 

 Gammarus platycheir; Crust. ; Amphipoda 

 Mctamysis strauchi; Crust. ; Mysidacea 



DIPHYLLOBOTHRIIDAE 



Diphyllobothrium ranarum — Cyclops fuscus; Crust. ; Copepoda 

 Diphyllobothrhim decipiens — Cyclops sp. ; Crust. ; Copepoda 

 Diphyllobothrium erinacei — Cyclops sp. ; Crust. ; Copepoda 

 Diphyllobothrium mansoni — Cyclops sp. ; Crust. ; Copepoda 



Cyclops strenuus; Crust ; Copepoda 



PROTEOCEPHALIDAE 



Proteocephalus amblopUtis — Hyalella asteca; Crust.; Amphipoda 

 Cyclops serrulatus; Crust. ; Copepoda 

 Cyclops viridis; Crust. ; Copepoda 



Proteocephalus pingiiis — Cyclops serrulatus; Crust. ; Copepoda 

 Cyclops viridis; Crust. ; Copepoda 



Ophiotaenia testudo — Cyclops sp. ; Crust. ; Copepoda 



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