DIGENETIC TREMATODES 53 



Taxonomy: Skrjabin (1947c) retained this form in the genus Psilostomum, but 

 Yamaguti (1958) erected the new genus Pseudopsilostoma to include this 

 form. Psilostomum ondatrae Price, 1931 of Beaver (1939) was considered 

 to belong to Riheiroia bj' Yamaguti (1958). If Yamaguti is correct, the 

 life cycle as worked out by Beaver (1939) does not apply. The taxonomy 

 of these forms needs clarification. 



Biology: Kuntz (1951) discussed the embryology of the excretory system. 



Family SCHISTOSOMATIDAE 



Trichobilharzia adamsi Edwards and Jansch, 1955 



Host: Physa conformis B.C. Edwards & Jansch, 1955 



Only record. One immature female was recovered from a duckling. Edwards 

 and Jansch (1955) described and figured all the known stages. This form can 

 cause cercarial dermatitis in man. 



Trichobilharzia elvae (Miller, 1923) 



Synonym : Cercaria elvae Miller, 1923 



Hosts : Lymnaea stagnalis Wash. Macy & Moore, 1953 



L. stagnalis jugulus Wash. Schell, 1959 



Lymnaea palustris 



miitalliana Wash. Hunter et al., 1949; Schell, 



1959 

 Lymnaea palustris 



nuftalliana Idaho Schell, 1959 



Ducklings Experimentally Macy, Moore, & 



Price, 1955 



This form has also been reported from Michigan by Miller (1923). 



Taxonomy: Macy and Moore (1953) beUeved this to be a vaUd species, but 

 McMullen and Beaver (1945) believed it to be a synonj'm of the European 

 species T. occUata. The morphology was discussed bv McMullen and Beaver 

 (1945). 



Biologj' : Furcocercous cercariae develop in the snail hosts and develop to 

 maturity in birds. When the cercariae penetrate the skin of man they 

 produce cercarial dermatitis (Macy, Moore, and Pi-ice, 1955). 



Trichobilharzia oregonensis (MacFarlane and Macy, 1946) Macy and Moore, 

 1953 



S}-non3'm : Cercaria oregonensis McFarlane & Macy, 1946 



Hosts : Physa ampullacea Ore. McFarlane & Macy, 1946 



Ducks Experimentally Macy, Moore, & 



Priced 1955 

 Geese Experimental!}' Macy, Moore, & 



Price, 1955 



This form is known only in the Pacific Northwest. 

 Morphology: Well described and figured by Macy, Moore, and Price (1955). 



