35] PROTEOCEPHALIDAE — LA RUE 35 



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



robust Proteocephalus ambloplitis (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 Yz-Va 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 l / 2 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 diibius 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 y 3 across breadth of pro- 

 glottid _„_ 36 



36(39) Testes in 1 layer _ „.„ _... 37 



37(38) Cirrus-pouch extends Yz~Y 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 2 / 9 - 1 / 7 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 



