344 ^ lc Scottish Naturalist. 



of performing the function, in this respect, of the grown examples, 

 and this often earlier in the season than the salmon itself. 

 Although this strange phenomenon was known to Willoughby, it 

 is perhaps no nearer a satisfactory solution than it was in his day. : 

 It is certainly not easy to account for it on any hypothesis, but 

 much more difficult, as it appears to me, on the untenable 

 theory, that these little fishes are young salmon of pure breed. 

 Dr. Knox, who made the parr an object of special study, and 

 who was well acquainted with the development of the salmon 

 in all its stages, as far at least as they are known, or perhaps 

 knowable, was of opinion that the parrs showing this pre- 

 cocity were not of pure breed, but were hybrids of many kinds. 

 This may not imply that all these parrs are the offspring of 

 parents in which hybridism is so strongly manifest that it is 

 apparent at first sight. In numerous instances they may be the 

 consequence of hybridism acting on and through a number of 

 individuals. If these parrs are hybrids, and I do not suppose 

 that there are many naturalists, who have studied the matter, 

 that have much faith in the belief pretty generally entertained 

 by the public, that they are genuine young salmon, then of 

 course they can never become large or adult examples of that 

 fish, although they may through time assume an appearance 

 exceedingly like it. The question is, if they do not become 

 salmon, to what do they grow ? Are they the young hybrid fish 

 known in our rivers after they grow large, under the name of 

 bull-trout ? I do not mean S. trutta, nor S. eriox, which some- 

 times go by that name, but that anomalous fish, neither the 

 one or the other, that is said to be increasing too rapidly in 

 some rivers for the well-being of the salmon. Dr. Giinther states 

 that in one specimen of bull-trout from the Beauly, examined by 

 him, the number of pylaric appendages was found to be as low as 

 fifty-four. This is as in the sea-trout, "yet the relative size of the 

 scales on the tail is in all these bull-trout the same as in the 

 salmon." Mr. Buckland says, " That amongst some specimens 

 of trout sent him from the Tees, there was one which, from 

 anatomical indications, he would pronounce a hybrid between 

 S. salar and S. eriox." Formerly the prolific, or second year 

 parrs, were caught by anglers in dozens every summer, and the 

 trout were kept within proper bounds by other means. Mr. 

 Stoddart, speaking of the bull-trout in the Tweed, and more par- 

 ticularly the Yarrow, says, "Of the slaughters achieved on which, 

 in the golden days of the Ettrick Shepherd, I retain flaming 



