51] PROTEOCEPHALIDAE — LA RUE 51 



Schneider found a small receptaculum seminis just anterior to the 

 ovary. According to Schneider the passages in the interovarial space 

 bear the relations customary to Proteocephalids. The ovary is bilobed, 

 the lobes being like two elongated balls connected by a slender arched 

 mid-piece. The vitellaria are lateral, follicular, sparse, and the indi- 

 vidual follicles are small. The uterus was not observed by Schneider. 

 It is not well developed in any of the specimens examined by the 

 writer. Schneider saw the opening of the uterine passage and the pre- 

 formed uterus opening just a little posterior to the middle of the pro- 

 glottid. No eggs were seen. No proglottids were ripe. 



This species is quite closely allied to the P. filicollis (Rud)^ 

 (amhiguus) described by Gui. Schneider (1905). However it is differ- 

 entiated from P. filicollis by its much longer cirrus-pouch and by its 

 larger testes. P. filicollis (Schneider's specimen) shows a slight genital 

 prominence upon which the genital pore is situated. It differs very 

 markedly from the P. pinguis La Rue found in our North American 

 Esox lucius. The P. pinguis is a larger worm with a larger head, larger 

 suckers, a functional fifth sucker, a relatively shorter cirrus-pouch, and 

 a larger number of testes. P. fallax La Rue, P. exiguus La Rue, P. 

 pusillus Ward, and P. percae (0. F. Miiller) are readily distinguished 

 from P. esocis by means of the fifth sucker and many other character- 

 istics which are best shown in the comparative tables. P. macrocephalus 

 (Creplin), a form without a fifth sucker, is much larger, has more 

 numerous testes, a relatively shorter cirrus-pouch and in other ways 

 also it differs widely from P. esocis (Schneider). 



PROTEOCEPHALUS AGONIS (Barbieri) 

 [Figs. 158, 174, 185] 



1909: Ichthyotaenia agonis Barbieri, 1909:334-341 

 1911: Proteocephalus agonis La Rue, 1911:475 



Specific Diagnosis: Characters of the genus. Cestodes of small 

 size. Strobila 3-4 cm. long, maximum breadth of same about 0.5 mm. 

 Scolex small, 0.168 mm. in diameter, unarmed. No fifth sucker. Suck- 

 ers circular, symmetrically arranged on head, size? Neck quite long, 

 as much as 3 mm., breadth 0.140 mm. Neck not well differentiated 

 from strobila. Proglottids very variable in form and number. At 

 times as many as 50-70. First proglottids broader than long. Mature 

 proglottids longer than broad, 0.580-0.620 mm. long by 0.330-0.370 mm. 

 broad. Ripe proglottids filled with eggs, nearly quadrate, length and 

 breadth about 0.5 mm. 



