Tlie Scottish Naturalist. 343 



examined both parr and smolt from that river, and convinced 

 myself, and perhaps others, that several of these were un- 

 doubtedly young salmon. In examining parr it has to be borne 

 in mind — a fact which, although known long ago, seems strangely 

 lost sight of — that all young salmonoids, including, of course, 

 the young of the river-trout, as well as the migratory species, 

 are at one time parr ; that is, they are barred transversely much 

 in the same manner, and of the same colour, as the young of 

 the [salmon. There is sometimes a little difference in the 

 breadth, and perhaps the number of the parr markings, but at 

 one period of life they are invariably present. The parr state 

 is considered by some naturalists as an embryonic condition 

 through which the whole genera, if not family, pass ; and when 

 it is added that the influence of hybridism, which is very 

 prevalent amongst this class of fishes, has to be carefully 

 considered and allowed for, it will be seen how cautiously 

 determinations require to be made, when dealing with the young 

 or imperfectly developed animal. 



The parr of the salmon, when of pure breed, is, I should 

 say, always determinable with more or less certainty. In 

 the case of the other migratory species — and to some extent 

 the river-trout — it is, I believe, impossible when in the parr or 

 orange-fin stage, to distinguish absolutely the one from the 

 other, by external appearance at anyrate. The coloration is 

 alike variable, and the dentition is the same in all; there seems 

 to be no invariable feature whereby they can be identified until, 

 in the case of the latter, after their first return from the sea, 

 when they have commenced to assume the specific characters 

 possessed by the adult members of the species to which they 

 belong. Valenciennes endeavoured to establish a system of 

 classification of the Sal/nonidce, on the arrangement of the 

 vomerine teeth. This did well enough when confined to grown 

 specimens ; but was of no use whatever when applied to young 

 individuals. He considered, however, that distinctive characters 

 should be taken from adult examples only. 



Amongst the parrs to be met with in summer and autumn, in 

 most salmon rivers, numbers of the males have the milt fully devel- 

 oped ; while the roe in the ferfiale remain at a minimum. This curi- 

 ous anomaly involves some of the highest problems in animal 

 physiology, and is, so far as I am aware, without a parallel in any 

 other department of zoology, viz., that of a young animal, while still 

 in the embryonic condition, being sexually mature, and capable 



