72 ILLINOIS BIOLOGICAL MONOGRAPHS [72 



this point needs confirmation. The Taenia longicollis and T. ocellata 

 from Coregonus fera are probably identical. Zschokke's description of 

 his Taenia longicollis was no doubt based on specimens from Coregonus 

 fera for he wrote (p. 14) : "Pendant mes recherches je l'ai trouve en 

 grande quantite dans les appendices pyloriques et dans les intestines 

 greles de Coregonus fera, et une fois, en Fevrier, enkyste sous sa forme 

 larvaire dans le f oie de Salmo Umbla. ' ' 



Fortunately Dr. H. B. Ward has received some specimens from 

 Professor Zschokke labelled, "Taenia ocellata, Coregonus fera." These 

 have been found to be identical with Kraemer's Taenia ocellata from 

 Coregonus fera, Lake Lucerne, and they have proved to be a new species 

 to which the writer (La Rue 1911) gave the name of P. fallax La Rue. 

 It is highly probable that the specimens from Coregonus fera identified 

 by Zschokke (1884) as T. longicollis belong to this same species. The 

 T. longicollis of his description differs from that of Kraemer (1892) 

 chiefly in length. The small head, large cirrus-pouch, the proportions of 

 the proglottids, position of the genital pore, and the size of the cirrus- 

 pouch agree pretty well with the facts for P. fallax La Rue. Zschokke 

 (1884) presented no data to show that he had made a comparative study 

 of the specimens collected by him from Salmo umbla and from Trutta 

 variabilis. It is scarcely possible to determine where these specimens 

 belong, and speculation without some basis of fact is worth but little. 



Kraemer (1892) as a result of his study of specimens taken from 

 Coregonus fera, Lake Lucerne, in July, identified these specimens as 

 Taenia filicollis Rud. Later in the same season (about Sept. 1) he took 

 more specimens from Coregonus fera. These he identified as Taenia 

 ocellata on account of their greater length. His specimens collected in 

 July measured 30-60 mm. Those taken by him in September measured 

 as much as 100 mm. Kraemer now made a careful comparison of these 

 two forms. He found that they agreed in every particular as to size of 

 the head and suckers and as to the presence of a fifth sucker. In the 

 internal anatomy of the proglottids and in the histological structure of 

 the organs the two forms also agreed perfectly. Moreover among his 

 specimens he found gradations in length from the shortest to the longest. 

 On these grounds Kraemer concluded that Taenia filicollis Rud. and 

 Taenia ocellata Rud. were one and the same; that in fact the smaller 

 Taenia filicollis was but an incompletely developed Taenia ocellata. 

 Kraemer was correct in concluding that these larger and smaller speci- 

 mens in his possession belonged to the same species. However, his con- 

 clusion has nothing whatsoever to do with Rudolphi 's Taenia ocellata and 

 T. filicollis for the very good reason that Kraemer's specimens belonged 

 to neither of Rudolphi 's species. 



