Il62 BULLETIN OF THE BUREAU OF FISHERIES. 



In a later paper Zschokke (1896) lists the parasites of salmon caught in the 

 Rhine at Basel, including the results of examinations extending over several 

 years and embracing 16 species, as follows: 



Bothriocephalus infundibuliformis Diesing. 



Tetrarhynchus solidus Drummond. 



Tetrarhynchus sp. 



Schistocephalus dimorphus. 



Distomum varicum Zeder. 



Distomum appendiculatum Rudolphi. 



Distomum ocreatum Rudolphi. 



Distomum reflexum Creplin. 



Distomum miescheri Zschokke. 



Ascaris clavata Rudolphi. 



Ascaris capsularia Diesing. 



Ascaris sp. 



Ascaris sp. 



Echinorhynchus clavseceps Zeder. 



Echinorhynchus acus Rudolphi. 



Pisicola geometra Linnaeus. 



Unreported previously are Echinorhynchus clavceceps Zeder, Pisicola geom- 

 etra Linnaeus, and possibly also two undetermined species of Ascaris. Elimi- 

 nating forms which do not properly belong to the Rhine at Basel and adding 

 species recorded previously, the net result is 17 species of parasites in the salmon 

 at Basel, or one-third of the total known parasitic fauna of that region. Of 

 these 17, 13 are characteristic of the salmon and wanting in other fish there. 

 The large majority of the list are of purely marine character and a further 

 group is characteristic of migratory fish, leaving nothing of a limnetic type 

 save Pisicola geometra, a leech which is merely a temporary ectoparasite. 



This paper records also the results of the examination of additional salmon 

 from the North Sea, the lower Rhine, and the middle and upper Rhine, making 

 the grand total of 1 79 Rhine salmon examined by this author. The only new 

 parasite recorded is Scolex polymorphus Rudolphi. Again, later, Zschokke 

 (1902, p. 128-130) discusses the records of his earlier work without adding any 

 new data. 



In studies on the Rhine salmon Hoek (1899) records that he found in the 

 young fish an ascarid, according to Fritsch .4. clavata, and repeatedly specimens 

 of a species of Echinorhynchus which Fritsch names E. pachysomus Creplin, 

 though he did not observe it in the young salmon. In Hoek's opinion the forms 

 obtained, though not fully grown, agree better with the description of E. proteus 

 Westrumb, and indeed with the more limited concept of the name according to 

 Hammann. Hoek observed not infrequently that young salmon were infested 

 with a leech, Cystobranchus (Pisicola) respirans Troesch, which lived as an 

 ectoparasite on the skin. 



