Il66 BULLETIN OF THE BUREAU OF FISHERIES. 



Tetrarhynchus solidus, from the abdominal cavity; a single specimen loose 

 in peritoneal cavity. 



Bothriocephalus proboscideus , from intestine and pyloric cceca; exceedingly 

 common and most so in largest and fattest salmon. 



One should always recall the relative value of such comparisons as those in 

 the preceding pages. The fact that from Irish salmon only 6 species of para- 

 sites are recorded, from the Scotch form lo species, from the Baltic form 14 spe- 

 cies, and from the Rhine salmon 20 species, is partly accounted for by the amount 

 of attention directed to the various forms. Thus the first record concerning the 

 Rhine salmon (Zschokke, 1889) listed 11 species of parasites obtained in the 

 course of examining 45 specimens of the Rhine salmon. The second record by 

 the same author (Zschokke, 1891) included 20 species of parasites from 129 

 hosts, and the third record (Zschokke, 1896) gave 23 species of parasites from a 

 total of 179 hosts. Of these 136 came from the Rhine itself and 43 from the 

 sea. More extended study of any host will increase the list of the parasites 

 which it is known to support. 



The same species of fish, Salmo salar, occurs in streams on the western or 

 American coast of the Atlantic Ocean. Thus far no one appears to have devoted 

 especial attention to the parasitic fauna of the American fish, but some scattered 

 references to species found in our American salmon are recorded by difi"erent 

 authors. No doubt the list can be extended considerably by longer search, 

 but so far as I can ascertain the following brief references include all records of 

 salmon parasites made on this continent and published up to the present time. 



According to Zschokke (1891) Leidy reported Bothriocephalus cordiceps 

 from the intestine of Trutta salar Linnaeus. The reference, which is apparently 

 cited from von Tinstow (1878), is incorrect both in location and content. Leidy 

 (1871) reported on the authority of Professor Hayden "the brook trout, Salmo 

 fontinalis, of the headwaters of the Yellowstone River, to be much infested 

 with a species of tapeworm * * * from the abdominal cavity, but not from 

 the intestinal canal * * * jt belongs to the old genus Bothriocephalus , and 

 to that section now named Dib'othrium." This new species was named Diboih- 

 rium cordiceps. The species was subsequently studied in detail by Linton. I 

 am unable to find any other reference to this parasite in the writings of Leidy 

 or any record of its occurrence in any other than the original host, which was in 

 reality Salmo mykiss, the Rocky Mountain trout; the adult parasite occurs in 

 the intestine of the American white pelican, Pelecanus crythrorhynchus. This 

 parasite accordingly seems to have no relation whatever to the salmon and 

 should be eliminated from the list of its parasites. 



In the catalogue of parasites from various collections in the United States 

 by Stiles and Hassall (1894) there are listed from Salmo salar Bothriocephalus 



