101] PROTEOCEPHALIDAE—LA RUE 101 



other species than Perca fluviatilis, P. norvegica, and Acerina cernua. 

 Zschokke (1884) reported this species from several hosts, and from the 

 same host species he reported several other species of Taenia. A number 

 of years later Kraemer, a pupil of Zschokke, attempted to prove that 

 Taenia filicollis was the young stage of Taenia ocellata, and since the 

 appearance of Kraemer 's work (1892) Taenia filicollis and Taenia 

 ocellata have for the most part been considered to be identical. As a 

 result of the tacit acceptance of this determination great confusion 

 exists in the identification of many lots of specimens. It is therefore 

 difficult or, indeed, quite impossible to tell what references among the 

 later writers should be considered in the synonymy of Proteocephalus 

 percae. An actual study of many of the specimens bearing these much 

 debated names must be made before an exact determination is possible. 

 A comparative study of specimens of this genus now to be found in the 

 helminthological collections in Europe would doubtless yield many inter- 

 esting results. In the preparation of this monograph five lots of material 

 identified as Taenia ocellata Rud. have been studied. Four of these 

 lots were received from European investigators, another from an 

 American. Out of these five lots four have proved to be new species 

 reported by La Rue (1911) while the fifth was Proteocephalus percae. 

 La Rue (1911:475) gave this species a place in a list of Proteocephalus 

 species. 



Professor Ward secured from Professor Levander, Helsingfors, 

 Finland, some specimens of Schneider's species, Ichthyotaenia percae 

 (0. F. Muller) and I. ocellata (Rud.) This material included both 

 alcoholics and slides. One bottle, now No. 10.123 in Professor Ward's col- 

 lection, bears the original label: "Ichthyotaenia percae 0. F. M. Det. 

 G. Schneider." A second bottle of this material, now No. 10.122, in Pro- 

 fessor Ward's collection, bears the original label: "Ichthyotaenia ocel- 

 lata Rud. Coregonus lavaretus. 14, V, 02." The two slides were labelled 

 "Ichthyotaenia ocellata, Coregonus, 24, VIII, 01." From this data it 

 seems that these must have been prepared from the same lot which 

 Schneider mentioned in his report (1902:23 and 53). Sections and toto 

 preparations were made from specimens of lot No. 10.123, while sections 

 only were prepared from lot No. 10.122. Some of the heads of each lot 

 were cleared in glycerine. 



A comparison of Schneider's descriptions of his Ichthyotaenia 

 percae and his 7. ocellata show but two significant differences between 

 the species. He states that the head of I. percae is much the larger but 

 that the main difference between them is in the presence in the head 

 of I. ocellata of "einen fiinften flachen Saugnapf von 40/i im Durch- 

 messer an der Spitze, der offenbar auch noch funktioniert, da er aus 



