98 ILLINOIS BIOLOGICAL MONOGRAPHS [98 



Perca cernua is now known as Acerina cernua while the Perca 

 marina should be known as Sebastes marina, according to Jordan and 

 Evermann (1896-1900). Rudolphi (1819) stated that Perca marina did 

 not occur in Muller 's region and that the latter 's specimens came from 

 Perca norvegica. It seems very doubtful that the species designated 

 by Muller as Perca marina and by Rudolphi as Perca norvegica can be 

 identical with Sebastes marina, for the latter is a marine fish whereas 

 the host of Taenia percae must be a freshwater fish since the genus 

 Proteocephalus occurs only in the fishes of freshwater. Dujardin 

 (1845:583) and Diesing (1850:513) added almost nothing to the data 

 as given by the earlier investigators. 



Van Beneden (1861:165) briefly reported Taenia ocellata but gave 

 no drawings. He stated that the perch was the host. Von Linstow 

 (1878:208, 209) did not increase the list of hosts. Zschokke (1884: 

 16-17) reported and described a cestode from Perca fluviatilis, Lake 

 Lucerne which he identified as Taenia filicollis Rud. As shown in an- 

 other part of this work his specimens are probably to be considered as 

 belonging to the species, P. dubius. Under the name of Taenia ocel- 

 lata Zschokke (1884:13, 14) described a form from several hosts includ- 

 ing Coregonus fera. It seems not at all unlikely that this species is the 

 same as the one from Coregonus fera which Kraemer (1892) first de- 

 scribed as Taenia filicollis and later in the same article as Taenia 

 ocellata. Kraemer 's species has been shown elsewhere in this mono- 

 graph to be very different from Taenia percae, and it was described 

 by La Rue (1911) as a new species, P. fallax. A more complete discus- 

 sion of Zschokke 's and Kraemer 's work above cited will be found in the 

 description and synonymy of P. fallax. Lonnberg (1889:14) reported 

 Taenia ocellata Rud. from Perca fluviatillis, Upsala. His diagnosis is 

 short, yet sufficient data are given to enable one to determine that this 

 form is not the same as that one which he reported (1889:15) from 

 Gasterosteus pungitius and identified by him as Taenia filicollis Rud. 

 Lonnberg 's Taenia ocellata was nearly 3 mm. broad by 150 mm. long. 

 It is highly probable that this form is identical with the Taenia percae 

 Muller. Linton (1897:425-426) provisionally assigned to this species 

 some cestodes which in all probability belong to Proteocephalus amblo- 

 plitis (Leidy). Von Ratz (1897:453) reported finding Ichthyotaenia 

 ocellata in Esox lucius and Lucioperca sandra in Lake Balaton. It seems 

 improbable that his determination was correct. Miihling (1898:36) 

 found what he determined to be Ichthyotaenia ocellata in Perca fluvia- 

 tilis and Gasterosteus aculeatus at Rositten, East Prussia. It seems 

 probable that he has made a misdetermination in the case of the cestodes 

 found in Gasterosteus aculeatus. 



