Its outward Characteristics. 219 



of many investigations has led me to establish the fin formula 

 as follows : — The gill rays being 11 to 12, D 14, P 13-14 

 V9-10, A 10, C 2144.* 



The head of the silvery salmon trout is bluish-black above, 

 silvery on the cheeks, increasing to pearl-white on the throat. 

 There is often a tinge of brown on the lower jaw and pre- 

 operculum. In fresh specimens captured in rapids during 

 the breeding season, and in spring, there will be found nume- 

 rous dark circular spots on the crown of the head. The back 

 and tail are of the same colour, sides silvery, belly pearl-white 

 and spotless. Black spots extend over the dorsal region, on 

 its fins, and the tail, and along the sides of the body, between 

 the lateral line, but stop short of the belly. In males, a few 

 red spots are met with here and there in the centre of the! 

 black spots. The inner surfaces of the pectoral and ventral and 

 the sides of the anal fins are tinged with black. I have failed,, 

 among the extensive collections examined at all seasons, to 

 observe the X-shaped spots of the sea trout and sewin. Here 

 again there is another apparent distinction between it and its. 

 close allies. 



The eye is large in proportion ; its sclerotic is a dirty white, 

 and the iris pale yellow. The molten silver colouring of the 

 breeding season is especially brilliant in this fish, and the brown 

 taints on the head sometimes extend in irregular patches 

 along the abdomen ; indeed, when in full dress, I do not know 

 a more attractive salmonoid. 



The teeth are largest on the tongue, where they vary in 

 number from eight to twelve, decreasing relatively from the 

 outer maxillaries to lower labials, labials, palatines, and vomer. 



The average weight is from two and a half to three pounds, 

 but individuals are captured of seven pounds, and on reliable 

 authority I know of one caught through the ice on these lakes 

 weighing ten pounds and a half. Even larger fish are mentioned 



* Gilpin {op. cii., p. 88) gives the formula thus : D 12-13, P 14, V 9, A 9, 

 C 20, but the number varies, and dividing rays are apt to be counted as 

 two. 



