45 



On those parent fisli wliich remain in the pond, the parr 

 * marks are most apparent immediately after the spawning 

 time, and the fish get gradually more and more silvery till 

 the height of summer. 



The deficiency in the number of the pyloric appendages 

 seems far more difficult to account for than the mere varia- 

 tion in colour ; yet even in this case may not variation be 

 due to the unnatural detention in fresh water? It is 

 certain that the number of these appendages varies greatly 

 in individuals belonging to the same species. Br. Giinther 

 gives 36 as the normal number for the river- trout (Sal mo 

 fario), yet I have found more than 40 iu several specimens 

 undoubtedly belonging to the latter species. • 



One of the parent salmon trout from our pond, a male, 

 which died nearly a year before that sent to England, and 

 which is now in the Museum, was dissected in my presence by 

 our curator, Mr. Eoblin, who carefully counted the pyloric 

 appendages, and found 47. With these facts before us, we 

 should not place too much reliance on the number of the 

 pyloric appendages as a specific test. Such facts only show 

 the difficulty of what Dr. Giinther, in his preface to the Cata- 

 logue of the Fishes in the British Museum, vol. 6, 1866, calls 

 " finding a way through this vast labyrinth of variation of 

 character in the salmonidse." 



Dr. Giinther speaks of having found 36 pyloric appen- 

 dages in hybrids between river and sea-trout ; but where were 

 such hybrids obtained, and how was the fact of their being 

 such hybrids authenticated ? To obtain a hybrid between 

 these fish, at the same stage of growth as the parent fish sent 

 hence, the ova and milt must have been obtained, the fish 

 hatched and carefully attended to for four years by compe- 

 tent persons. Has this ever been done ? 



After all, the fact that the parent fish, in every minute 

 external detail of measurement, corresponded exactly with 

 the true salmon trout, and differed totally from the true 

 river-trout, while in colour it resembled neither, proves that 

 it was no hybrid beween those fish ; and the circumstance 

 of its having the same number of pyloric appendages as such 

 hybrids therefore matters little. 



With regard to the two smaller fish examined by Dr. Giin- 

 ther, his written descriptions correspond with those of the 

 young of true salmon (Salmo salar). Yet these were bred from 

 eggs deposited by fish which never went to sea, and which 

 externally [are identical -with the large parent fish sent to 

 England ; and I am, therefore, driven to the conclusion that, 

 at this early period of their growth, the migratory species 

 of salmon cannot, with any degree of certainty, be distin- 

 guished from one another. 



