DIGENETIC TREMATODES — MANTER AND VAN CLEAVE 327 



japonicum (Yamaguti, 1934), new combination; (synonym Stephanochas- 



mus japonicus Yamaguti, 1934) 

 lineatum Manter, 1934 

 tnegacephalum Manter, 1940 

 micro stephanum Manter, 1934 

 minutum (Looss, 1901) Manter, 1940 

 multispinosum Manter, 1940 

 pristis (Deslongchamps, 1824) Looss, 1899 

 proviicropsi Manter, 1947 

 rhombispinosum (Labour, 1908) Manter, 1934 

 senium (Linton, 1910) Manter, 1947 

 tenue (Linton, 1898) Linton, 1940 

 triglae (Lebour, 1908) Dawes, 1946 

 tristephanum McFarlane, 1935 



27 (26 



28 (15 



29 (40 



30 (31 



KEY TO SPECIES OF STEPHANOSTOMUM 



Three rows of oral spines — - 2 



Spines very numerous (140 or more) 3 



Vitellaria extending anterior to acetabulum microstephanum 



Vitellaria not reaching acetabulum tristephanum 



Spines 50 to 52 - lineatum 



Two rows of oral spines 7 



Vitellaria interrupted opposite testes. 8 



Oral spines rhomboid rhombispinosum 



Oral spines elongate 10 



Oral spines 36; vitellaria not reaching cirrus sac pristis 



Oral spines at least 48; vitellaria reaching cirrus sac — 12 



Sucker ratio 1:1__.- caducum* 



Sucker ratio 1 : 2 promicropsi 



Vitellaria not interrupted opposite testes 15 



Vitellaria extending to posterior edge of acetabulum 16 



Oral sucker larger than acetabulum.— fistulariae 



Oral sucker smaller than acetabulum - 18 



Oral spines very numerous (about 80)—- multispinosum 



Oral spines considerably fewer than 80. 20 



Eggs 96 to 126fi long. 21 



Suckers subequal triglae 



Sucker ratio about 1:1.4 to 1.6 1 japonicum 



Eggs 56 to SOfi long 24 



Oral spines 24 elongatum 



Oral spines 36 or more 26 



Oral spines 36; prepharynx considerably longer than 



pharynx — casum 



Oral spines 48 to 50; prepharynx not considerably longer 



than pharynx dentatum 



Vitellaria not reaching acetabulum 29 



Vitellaria reaching only to base of cirrus sac or slightly beyond— 30 

 Oral spines 56; eggs 87 to 101^ baccatumo 



* Lebour's (1907) specimen of S. caducum from the whiting did not have interrupted vitellaria. 

 It may represent another species. It is much like S. ditrematis except for its equal suckers. 



" NicoU's original specimen of S. haccatum had vitellaria extending only to base of cirrus sac. 

 He later described a somewhat more anterior extent but not to the acetabulum. Manter's (1926) 

 fieure shows the vitellaria to the acetabulum. Thus, there is some uncertainty regarding this 

 character in this species. 



