812 THE FKKSII-WATER FISHES OF EUROl'K. 



The caudal, adipose fin, the inner side of the pectoral, and ventral, are blackish, 

 with the outer side colourless. 



There are fifty-nine to sixty vertebra? ; and usually from forty-nine to sixty- 

 one pyloric appendages. 



Like its allies, this fish is sometimes found sterile, and then remains in the 

 sea, where it is known to the Prussian fishermen as StrantUachs. The 

 breeding fishes are believed to remain in fresh water longer than the Salmon, 

 and to spawn from September to November. This Trout makes its way up 

 the small tributaries. 



In France it is found only in the Loire, the Seine, and the Meuse. 

 It is recorded by Steindachner from Spain. It goes up the Rhine to the 

 Moselle, and is occasionally taken at Metz ; and, like the Salmon, it ascends the 

 Weser, Elbe, and other rivers of North Germany. 



We have regarded the Bull Trout, or Sewin of Scotland, which Yarrell iden- 

 tified with the Salmo eriox of Linna?us, as only a condition or variety of Salmo 

 trutla ; but it is at present imperfectly understood, and Dr. Giinther records 

 his conviction that it comprises 



(1), Hybrids between the Salmon and Sea Trout; 



(2), Salmon which have prematurely returned from the sea after spawn- 

 ing; and 



(3), Sterile fish. 



Dr. Giinther mentions having seen in the month of August, in the Beauly, 

 in Scotland, thirty Salmon to three Bull Trout and one Sea Trout ; and adds 

 that the differences between the Bull Trout and Salmon are sometimes so slight 

 as to be scarcely perceptible to an inexperienced eye. 



Yarrell regarded the form of the opercular bones as furnishing an infallible 

 distinction, but we have already seen that the opercular bones are liable to un- 

 expected variation. The Welsh fishermen apply the name Sewin to these fish, 

 which are commonly of fifteen to twenty pounds' weight. We may add that 

 if Salmo eriox is a hybrid with the Salmon, it is fertile, and is found with the 

 spawn well developed. 



Lord Home did not find any difficulty in distinguishing Salmon Trout from 

 Bull Trout, and states that the latter is an inferior fish, which replaces the 

 former in several Scottish rivers. 



He mentions that they do not enter the river till the Salmon have com- 

 menced spawning, and observes that, though he had killed more Salmon with 

 the rod than any other man, yet he had not killed twenty clean Bull Trout, 

 though Bull Trout Kelts may be killed in thousands. 



