THE SALMON 27 



tinguish Salmon from Trout we may note that the 

 dorsal fin has usually more rays (10, exceptionally 9, 

 to 1 2 branched rays in the Salmon, 8 to 10, excep- 

 tionally 1 1, in the Trout), and that the scales on the 

 tail are larger, in an oblique series from the posterior 

 edge of the adipose fin downwards and forwards to the 

 lateral line numbering 10 to 13 in the Salmon, 13 

 (exceptionally 12) to 16 in the Trout; these figures 

 are based on an examination by the author of more 

 than a hundred examples of each species, and these 

 numerical differences are of special importance 

 because they are not subject to change with the 

 growth of the fish. In a Salmon the tail is more con- 

 stricted at the base of the caudal fin than in a Trout, 

 and consequently the anterior caudal rays form more 

 of a shoulder, so that a Salmon does not slip through 

 the fingers when grasped round the caudal peduncle, 

 but a Trout usually does ; the caudal fin is more or 

 less emarginate, or in large specimens truncate, or 

 even rounded, but is usually more distinctly notched 

 than in Trout of the same size. In adult Salmon 

 the anal fin is less pointed than in Trout, so that 

 when it is laid back the last ray usually extends 

 farther than the longest, the reverse obtaining in the 

 Trout. The maxillary extends to (in Grilse or small 

 Salmon) or a little beyond (in large fish) the vertical 

 from the posterior margin of the eye, being shorter 

 than in the Trout. 



Salmon live in the open sea, where they feed 

 on Herrings, Mackerel, Sand-eels, etc. ; they spawn 

 in fresh water from September to February, and 

 throughout the year they approach the coasts and 

 enter the rivers, in the estuaries often ascending with 

 the tide, and afterwards displaying great strength 



