Aethue. — Notes on some Specimens of migratory SalmonidsB. 191 



black spots, the absence of spots on the fins, and the colour of the fins, the 

 dorsal, adipose, and tail being black, and the pectoral, ventral, and anal 

 white, with more or less dusky shading ; the form and proportions of the 

 gill-covers, and the deciduousness of the vomerine teeth — these teeth being 

 fewer than in S. trutta. 



The salmon also attains a much greater weight than the sea-trout, and 

 its anal fin appears to be smaller in proportion to whole length of the body 

 than in S. trutta and S. fario. Comparing a number of Giinther's specimens 

 of S. trutta and 8. fario with three of S. salar, in regard to this proportion 

 of the anal fin, I find in the two former the ratio is as 1 to 12, while in the 

 latter it is as 1 to 16. (See table appended to this paper. Eefer also to 

 drawings of gill- covers.) 



The S. trutta is a shorter fish for equal weights than the salar, and it is 

 deeper or thicker at the origin of the tail ; the tail is generally square. The 

 colour of the back is darker, and the silvery scales (15 to 16 in transverse row) 

 more deciduous than in S, salar ; the spots are more numerous, but of the 

 same colour and shape, and there are usually a few present on the posterior 

 part of the dorsal fin. The fins are similar in colour to those of the salar, 

 the belly fins being rather whiter. The gill-covers differ to some extent, 

 the lower limb of the preoperculum being rounded and not so angular, and 

 the vomerine teeth are longer present than in S. salar ; also the fins are 

 longer, particularly the anal fin. 



The /Sf. fario may be generally distinguished from the two preceding 

 species by its olive-brown colour, round black spots, and its crimson spots. 

 But the same variety alters in colour according to sex, age, season, food, and 

 water. I find this so with our Otago-bred trout, from which my compari- 

 sons are mostly taken, just as many observers have at home in the fish of 

 English rivers. (Since beginning this paper, I have had several excellent 

 opportunities of again seeing our breeding-fish in spawning condition in the 

 Acclimatization Society's pond. The males, and more especially the largest 

 from 8 lbs. to 10 lbs., are in colour a brown-yellow with a pink tinge in the 

 body, the back-fins and tail very pink, and the spots black and red, very 

 distinct ; the hook on mandible very large. Even the females, which were 

 silvery, had all pink-tipped adipose fins and faint red spots in some cases 

 above and below the lateral line. To-day, 11th August, I saw and handled 

 a number of these splendid trout from 3 lbs. to 8 lbs. in weight). Some of 

 our streams too have tidal estuaries, and the large trout which are believed 

 to visit the tidal water will, no doubt, acquire a more silvery hue than those 

 which do not. This tends to complicate the distinctions still more, and to 

 make it more difficult to detect the difference between these and the true sea- 

 trout. Yet, so far as my examinations have enabled me to judge, I find 



