55 



IRREGULARITY IN THE GROWTH OP THE SALMON. 



By M. Allport, F.L.S, F.Z.S., &c. 



(Bead 8tJi Octoler, 1872.J 



In the proceedings of the Zool. Soc. of London for 1870, 

 Part 1, which reached our library only a few weeks back, I 

 find a paper by Dr. James Murie, F.L.S. , Prosector of the 

 Society, entitled " Additional Memoranda as to Irregularity 

 in the Growth of Salmon,'' so completely bearing out my often 

 expressed conviction that the difficulty of determining the 

 various species of the salmonidse from immature specimens 

 amounts almost to an impossibility, that an extract may prove 

 interesting 



Dr. Murie' s paper refers more particularly to two fish, 

 reared in the Zool. Gardens, and figured in F. Z. S., 

 1868, Plate xxiii. In the present paper full details 

 are gone into showing the grounds for believing these 

 fish to be the young of true salmon (>S^. salar), the weak 

 places in the evidence being also fully pointed out. On the 

 whole, the evidence seems in favour of these fish being genuine 

 salmon, and this view is curiously confirmed by the wonderful 

 resemblance between one of these fish and the specimen in our 

 Museum, hatched from the eggs of S. salar, which specimen 

 died, after being detained in fresh water for two seasons, after 

 first assuming the smolt scales. Dr. Giinther, after a careful 

 examination of the two English fish, came to the conclusion 

 that they were not young salmon, but probably hybrids, and 

 based his opinion (amongst other reasons) on the fact that the 

 number of the pyloric appendages in them differed from that 

 found in Salino salar. After a most elaborate consideration 

 of the subject in all its details, Dr. Murie says : — 



"It seems to me also a legitimate inference that the two fishes 

 reared in our aquarium are Salmon, inasmuch as they difi'er in a far 

 greater degree from all other European species than from S. solar ^ 

 Indeed, as is broadly admitted in the British-Museum Catalogue, 

 p. 3, of the genus Salmo, ' The almost infinite variations of these 

 fishes are dependent on age, sex and sexual development, food, and 

 the properties of the water ;' hence this very same reasoning which 

 demonstrates pecuharities in the twe Salmonoids and brood in 

 question, logically points to their immaturity, retardation, or 

 masking of the normal adult characters of the species. If their 

 entire growth has been prejudicially influenced by continuous 

 retention in fresh water, so may a defect or abnormal number of 

 scales (two traversely) and pyloric appendages (three or four) be but 

 the concomitant efiect of unnatural development. " 



With this paragraph of Dr. Murie's paper I was much struck, 

 because early in 1871 1 sent to England a salmon trout (S. 



