INTERNAL PARASITES OF THE SEBAGO SALMON. 



"59 



and its most abundant guests are typically marine. In spite of a long and 

 repeated sojourn in the river it does not infect itself with a single fresh-water 

 parasite, a fact that indicates strongly the complete fasting of the salmon while 

 in the Rhine. In other migratory fish the marine elements become greatly 

 reduced or even disappear entirely. Yet tabular comparisons show that in 

 contrast with the Rhine salmon all other migratory fish infect themselves in 

 fresh water more or less strongly with parasites, thus indicating that whereas 

 the salmon fasts in the Rhine, its near relatives feed abundantly on wandering 

 from the ocean into the river. 



It was possible to examine also 34 salmon from the Baltic Sea; all of them 

 were infected, and a total of 12 species of parasites were recorded from them, 

 as follows: 



Ascaris adunca Rudolphi. 



Ascaris (Agamonema) capsularis Diesing. 



Ascaris (Agamonema) communis Diesing. 



Ascaris aculeati von Linstow. 



Echinorhynchus acus Rudolphi. 



Echinorhynchus pachysomus Creplin. 



Distomum varicum Zeder. 



Distomum appendiculatum Rudolphi. 



Bothriocephalus infundibuliformis Rudolphi. 



Bothriocephalus sp. 11 (lar\'a). 



Bothriocephalus sp. in (larva). 



Triaenophorus nodulosus Rudolphi (larva). 



The Baltic salmon is much more heavily parasitized than the salmon of 

 the Rhine. Seven parasites are common to both, and of these five are more 

 abundant in the Baltic salmon and two only more abundant in the Rhine 

 salmon, while six parasites of the former do not occur in the latter. The rela- 

 tive infestation of the two forms is shown in the accompanying synopsis : 



Of parasitic species found in the Baltic salmon, Bothriocephalus mjtmdi- 

 bulijorniis was present often in enormous numbers, and the same was true of 

 Distomum varicum. On the other hand Ascaris capsularis did not manifest 

 the frequence or the abundance already noted for the Rhine salmon. Every- 

 thing indicates a rich and uninterrupted consumption of food by the Baltic 



