404 FRESH-WATER BIOLOGY 

 135 ( I 3 2 ) Genital pore near acetabulum 



136 



136 (137) No conspicuous pharyngeal glands. . . . Plagiorchis Liihe 1899. 



Body elongate oval, somewhat attenuated at both ends, covered 

 with minute spines. Pharynx and esophagus of approximately equal 

 length, crura reach posterior end, or near it. Genital pore just an- 

 terior to acetabulum, median or slightly sinistral. Cirrus sac curved 

 around and reaching posterior margin of acetabulum, with large 

 vesicula seminalis. Testes round to oval, oblique, separated by 

 uterine branches. No receptaculum seminis. Ovary spherical, at 

 inner end of cirrus sac. Vitellaria with many closely crowded folli- 

 cles usually reaching posterior end. Uterine coils partly pretesticu- 

 lar, chiefly posttesticular. Eggs numerous. 



In intestine of insectivorous vertebrates, chiefly birds, but also 

 amphibians, reptiles and mammals, infection probably through in- 

 sects. 



Little specialized forms that constitute the type of the family and 

 from which other genera have diverged in several directions. 



North American species. 



Plagiorchis proximus Barker 1915. 

 Reported from the muskrat in North America. 



FIG. 701. Plagiorchis proximus. Ventral view. X 25. (After Barker.) 



137 (136) Conspicuous pharyngeal glands present. 



Glypthelmins Stafford 1905. 



Small, oval distomes with rounded ends and cylindrical body. Skin 

 spinous. Acetabulum smaller than oral sucker, anterior to middle of body. 

 Pharynx and esophagus present, pharyngeal glands conspicuous; crura 

 nearly reach posterior end. Testes small, spherical, at center of body, post- 

 acetabular, nearly symmetrical. Genital pore median between acetabulum 

 and fork of intestine. Cirrus sac overlaps acetabulum in part. Ovary small 

 at left of acetabulum, receptaculum seminis present. Uterus with numerous 

 short transverse coils within crura between testes and posterior end, spread- 

 ing somewhat beyond ends of intestine. Vitellaria lateral from fork of in- 

 testine nearly to end of crura. Eggs small, numerous. 



Single North American species known. 



Glypthelmins quieta Stafford 1900. 



In intestine of Canadian frogs. 



FIG. 702. Glypthelmins quieta. Magnified. (After Stafford.) 



