35] PROTEOCEPHALIDAE — LA RUE 35 



18(19) Vaginal sphincter very long and strong; eestode large, 



robust Proteocephalus amhloplitis (Leidy 1887) 



19(18) Vaginal sphincter short and weak; cestodes small „ 20 



20(23) Testes in 2 partial or complete layers „ „ 21 



21(22) Cirrus-pouch extends ^-34 across the breadth of the pro- 

 glottid ; ductus ejaculatorius forms several coils ; 75-90 



testes Proteocephalus filicollis (Rudolphi 1802) 



22(21) Cirrus-pouch extends about yi across the breadth of the 

 proglottid; ductus ejaculatorius nearly straight; 44-52 



testes Proteocephalus esocis (Schneider 1905) 



23(20) Testes in one layer Proteocephalus neglectus La Rue 1911 



24 ( 3) Functional (well developed) fifth sucker present 25 



25(26) Suckers pointed at posterior margin. 



Proteocephalus cy clops (von Linstow 1877) sp. inq. 



26(25) Suckers not pointed at posterior margin 27 



27(42) Testes number about 70 or less._._ 28 



28(35) Cirrus-pouch extends less than % across breadth of pro- 

 glottid 29 



29(32) Embryos 0.03 mm. in diameter or greater 30 



30(31) Uterine pouches 6 to 8 on either side; 30-35 testes situated 



in 1 layer Proteocephalus fallax La Rue 1911 



31(30) Uterine pouches 7 to 14 on either side; 55-60 testes situated 



in 2 partial layers Proteocephalus dubius La Rue 1911 



32(29) Embryos much less than 0.03 mm. in diameter. 33 



33(34) Uterine pouches 9 to 14 on either side ; 35-40 testes; cestodes 



very small _ Proteocephalus exiguus La Rue 1911 



34(33) Uterine pouches 4 to 9 on either side; 50-60 testes; cestodes 



of medium size Proteocephalus percae (Miiller 1780) 



35(28) Cirrus-pouch extends less than % across breadth of pro- 

 glottid 36 



36(39) Testes in 1 layer _ 37 



37(38) Cirrus-pouch extends Yz-Ya across the breadth of the pro- 

 glottid; 10-14 uterine pouches on either side; embryos 

 measure 0.016-0.018 mm. in diameter; cestodes slender. 



Proteocephalus pinguis La Rue 1911 

 38(37) Cirrus-pouch extends Va-V7 across the breadth of the pro- 

 glottid ; 6-12 uterine pouches on either side ; embryos 

 measure 0.0212-0.018 mm. in diameter; cestodes short 



and robust Proteocephalus cernuae (Gmelin 1790) 



39(36) Testes in 2 layers „ _ 40 



40(41) Uterine pouches 10 to 16 on either side; cestodes very small 



and weak Proteocephalus pusillus Ward 1910 



