386 FRESH- WATER BIOLOGY 



52 (51) Postero-lateral pockets present on pharynx. 



53 



53 (56) Testes two, more or less deeply lobed. 



Subfamily CLADORCHIINAE Fischoeder 1901 . . 54 



Amphistomes with more or less strongly flattened body, and with acetabulum usually con- 

 spicuously ventral, rarely only terminal. Testes branching or lobed. Cirrus sac incom- 

 plete or nearly wanting. 



^ In this subfamily belongs possibly the " Amphistoma grande Diesing" of Leidy from the terra- 

 pin which does not seem to conform to the species designated. The description is inadequate 

 for a final diagnosis. 



54 (55) Pharyngeal pockets small, not affecting external boundary of oral 

 sucker Stichorchis Fischoeder 1901. 



Body noticeably attenuated anteriorly, broadly rounded posteri- 

 orly. Margins rounded, dorsal surface high, arched, ventral flattened. 

 Acetabulum ventral. Pharynx lacking; crura not much separated 

 from lateral margins. Cirrus sac small, genital sucker not conspicu- 

 ous. Vitellaria well developed, mostly behind testes and median 

 to crura, as well as partly dorsal and ventral to same.^ 



North American species. 



Stichorchis subtriquetrus (Rudolphi) 1814. 



One species, St. subtriquetrus, the true Amphistoma subtriquetrum 

 Rud. In intestine of the beaver; Quebec, Ontario. 



FIG. 670. Stichorchis subtriquetrus. Dorsal view to show arrangement of 

 parts. Magnified. (After Duff.) 



55 (54) Pharyngeal pockets large, conspicuous, modifying greatly outline of 

 oral sucker Wardius Barker and East 1915. 



Moderate sized amphistomes with prominent pharyngeal pockets, and 

 large subterminal sucker. Esophagus well developed, without differ- 

 entiated regions; crura long and wavy. Testes slightly lobed, tandem, 

 in center of body. Ovary median, behind testes near posterior sucker. 

 Genital pore posterior to bifurcation of intestine. Vitellaria extend out- 

 side crura from oral to posterior sucker. 



Only one species. 



Wardius zibethicus Barker and East 1915. 



In cecum of muskrat. Regarded by these authors as the "Am- 

 phistomum subtriquetrum Diesing" of Leidy (1888). 



FIG. 671. Wardius zibethicus. Ventral view, specimen compressed. Magnified. 

 (After Barker.) 



5 (53) 



two testes, spherical ................. 57 



