1903 - 4 .] Mr Calderwoocl on Bull Trout of Tay and Tweed. 33 
that in our large rivers kelts frequently remain for surprisingly 
long periods after spawning. During a prolonged stay in fresh 
water the maggots remain fixed to the gills, and in some cases 
the fish do not regain their silvery appearance before entering the 
sea. The suggestion which I would venture upon is, that if such 
fish remain only a comparatively short time in the sea, or, it may 
be, remain a considerable time in the vicinity of the mouth of a 
large river like the Tay, the maggots will still be found attached 
to the gills on their return. Further, I think it very probable 
that the peculiar spotted appearance may arise under similar con- 
ditions ; that the fish having, as it were, failed to visit good feeding 
grounds, and being, it may be, less fully nourished than the 
average salmon, exhibits to a varying degree this peculiar speckled 
appearance. 
Since examining these fish, I find that in an addendum to 
Gunther’s Brit. Mus. Catalogue , vol. vi., reference is made to his 
seeing other specimens of bull trout taken from the Beauly. He 
states that in Lord Lovat’s opinion some of those Beauly fish are 
hybrids between the salmon and the sea trout, “ yet,” he adds, “ the 
relative size of the scales on the tail is in all these bull trout the same 
as in the salmon. Captain H. Fraser believes that other specimens 
of ‘ bull trout 5 are true salmon, which, having gone down to the sea 
as kelts, return to fresh water before having attained to the con- 
dition of well-mended fish. Thus, as regards the river Beauly at 
least, fishes named ‘bull trout’ do not constitute a distinct 
species.” This was written in 1866, and I gather from it that 
Dr Gunther would afterwards have probably altered the position 
which he assigns to ‘ the salmon bull trout of Parnell ’ taken from 
the Forth. 
Captain H. Fraser’s surmise is, I think, a correct one, applied not 
merely to Beauly fish but also to the so-called bull trout found 
in the Forth, Tay, Spey, Ness, and other rivers. 
Tweed Fish. 
Turning now to the bull trout of the Tweed district, we find 
at once a very different fish, and in this case a trout in reality. 
We have seen that Parnell classed his salmon bull trout under 
S. eriox, and I have ventured to assert that S. salar would have 
PROC. ROY. SOC. EDIN. — YOL. XXV. 3 
