114 ILLINOIS BIOLOGICAL MONOGRAPHS [114 



gave no description. Nufer (1905:75) in the report of an investigation 

 of Lake Lucerne reported Proteocephalus longicollis from Perca fluvia- 

 tilis, Alburnus lucidus, Squalius cephalus, S. leuciscus, Esox lucius, 

 Coregonus wartmanni nobilis, C. exigmis albellus, C. schinzii helveticus 

 and Salmo salvelinus. It is extremely doubtful if the specimens of Pro- 

 teocephalus which Nufer found in other than the salmonoid fishes be- 

 long to the species P. longicollis. Nufer 's tabulated description of P. 

 longicollis (Nufer 1905:147) is based almost entirely upon the work of 

 von Linstow (1891). The character of Nufer 's work has been discussed 

 at some length in connection with P. macrocephalus and P. torulosus. 

 Many of the statements made in those places regarding his work apply 

 here. 



A discussion of the facts brought out in this historical summary 

 cannot yield very satisfactory conclusions. For the most part the au- 

 thors cited have necessarily been compelled to depend upon the exter- 

 nal features of the worm for diagnostic characters. Benedict (1900) 

 showed how little dependence could be placed on such characters alone 

 for descriptive purposes. The earlier workers necessarily based their 

 conclusions on little else than external features, upon records of hosts, 

 and locality of collection. The host records of all the workers who 

 reported this species prior to Nufer and von Ratz show that these men 

 regarded this species as being peculiar to the salmonoid fishes and it 

 seems quite probable that they were correct in this respect. It is im- 

 possible to determine whether this species is parasitic in all the salmon- 

 oid fishes of the list or whether a number of cestode species have been 

 reported under the one name without a painstaking comparative study 

 of such specimens as exist in private and museum collections together 

 with a study of specimens from hosts and localities as indicated in the 

 list of hosts. It is not likely that this will be done, at least not for some 

 time. 



The question of priority of name is not an important one. This 

 species is known as one of Rudolphi's species probably on account of 

 the weight of Rudolphi's authority as much as on anything else. His 

 first notes on this species contain only the briefest diagnosis and he dis- 

 tinctly says, "Zeders Beschreibung ist vollkommen geniigend", etc, etc 

 (vide supra). In the light of this it seems that Zeder should be cred- 

 ited with the specific name longicollis. It is true of course that Rudolphi 

 was the first to use the combination Taenia longicollis. As to the use 

 of the name longicollis or some of the names that were proposed still 

 earlier, viz., Taenia Froelichii, T. salmonis wartmanni and T. eperlani, 

 it may be said that the identity of the last is not well known. Ru- 

 dolphi (1819) thought it was not identical with T. longicollis. T. sal- 



