DIGENETIC TREMATODES 55 



Cercaria robinsonensis Schell, 1959 



Host: Physa gyrina Idalio Schell, 1959 



This cercaria has not been reported elsewhere. It causes cercarial dermatitis 

 (Schell, 1959). 



Schistosoma haematobium (Bilharz, 1852) Weinland, 1858 



Lloyd (1913) reported a case of Bilharzia haematohia in Seattle, Wash- 

 ington, from a man who had come from Africa. This trematode cannot be 

 considered a part of the natural trematode fauna of the Pacific Northwest. 



Family SPIRORCHIDAE 



Spirorchis artericola (Ward, 1921) Stunkard, 1925 



Host: Clemmys marmorata Ore. Thatcher, 1954 



Morphologj-: Skrjabin (1951) described and figured the worm. The germ cell 

 cjxle was worked out by Cort, Ameel, and Van Der Woude (1954). 



Biology: Cercariae develop in sporocysts in Helisoma trivolvis then penetrate 

 the turtle (Pieper, 1953). Other life history studies have been made bv 

 Ward (1921) and Stunkard (1923). 



Family STEGODERMATIDAE 

 Deretrema cholaeum McFarlane, 1936 



Host: Sebastodes sp. B.C. McFarlane, 1936 



Unknown outside of the Pacific Northwest. 

 Morphology: Also figured and described by Skrjabin (1957). 



Family SYNCOELIIDAE 



Syncoelium katuwo Yamaguti, 1938 



Synoni-m: Syncoelium filifcrum (Sars) of Lloyd & Guberlet, 1936 (Manter 

 1954) 



Hosts: Oncorhynchus ncrka Wash. Lloyd & Guberlet, 1936 



O. gorhuscha Wash. Lloyd & Guberlet, 1936 



Additional host reported from Japan by Yamaguti (1938). 



Morphology: Adequate descriptions are available (Yamaguti, 1938; Lloyd and 

 Guberlet, 1936). 



Biology: The life cycle is unknown. Sars (1885) described 5". filiferum from 

 euphausids, and these are possible intermediate hosts. 



