CHAPTER XXIV. 



THE BULL TROUT, GREY TROUT, SEWIN, OR 

 ROUND-TAIL. 



THERE has existed much diversity of opinion as to the identities of the 

 Salmo eriox or bull trout and its beautiful brother Salmo trutta, or the sea 

 trout, and each of these have been mistaken or otherwise wrongly mixed 

 up -with the true salmon Salmo salar. The distinctions between them 

 however, are very marked, as I shall proceed to show. 



First, the form of the gill covers : those of the salmon almost in 

 their outline describe a semi-circle ; the gill covers of the bull trout a 

 blunt right angle ; and those of the sea trout a compromise between 

 the two. Secondly, the teeth are differently placed and of widely 

 different number in the sea trout from those of either of its relations , 

 the Salmo salar and Salmo eriox being but slightly different, except in 

 size. The teeth in the central bone of the mouth of a sea trout are 

 numerous and extended along it, whilst these teeth are often not present 

 in the salmon, having been lost during the first migration to the sea. 

 The teeth of the bull trout are also usually longer and sharper than the 

 salmon, or sea trout. Thirdly, the fins are, in the 



SALMON. 

 Tail Fin, 



When young, deeply 

 forked, almost like a dace 

 (see Dace), lees so about 

 third year ; and nearly 

 square about fifth year. 



Dorsal Fin, 

 Hinder origin half way 



between point of nose 

 to extreme end of tail. 

 Longest in third ray. 

 AdipoteFin. 



Hinder origin about half 

 way between origin of last 

 back fin ray and end of 

 tail. 



Pectoral Fins. 



Two-thirds length of head. 



BULL TROUT. 



Tail Fin. 



Square earlier, then 

 gradually convex (hence 

 F ' round tail"). 



Dorsal Fin. 



Begins about half way be- 

 tween end of nose and 

 origin of upper tail fin rays. 



Adipose Fin. 



Nearer to end of tail fin 

 than to origin of last 

 dorsal fin ray. 



Pectoral Fins. 

 Half length of head. 



SEA TROUT. 



Tail Fin. 



Shorter and smaller than 

 salmon of same eize, less 

 forked than salmon of 

 same age; becomes 

 square at about six years. 



Dorstal Fin. 



Hinder origin exactly half 

 way between point of nose 

 and end of tail fin. Second 

 ray longest. 



Adipose Fin. 



Half way between origin of 

 last ray of back fin and 

 end of tail fin. 



