398 Proceedings of Royal Society of Edinburgh. [sess. 
sea trout characteristics. Owing to the more or less familiar 
appearance of artificially reared specimens, a series of which I 
show in PI. II., one is prepared for the presence of spots 
below the lateral line (although in the largest specimen which I 
show, and which has been twelve months in a sea water pond, 
spots are less conspicuous), but the rather noticeable breadth of 
the caudal peduncle in the Galway specimen is certainly not 
in keeping with the shapely specimens which can be reared 
artificially, as it is opposed to the characteristics of young salmon, 
as insisted upon and figured by Dahl in Norway. 
The measurement of the caudal peduncle is contained in the 
length of the fish only Ilf times. 
In a Fochabers smolt retained in fresh water till three years old 
similar measurements give 13 ’6 times. In the Fochabers smolt 
placed for a year in a sea pond the measurements give 15*2 
times. 
In a small Beauly grilse of 1 lb. 15| oz. similar measurements 
give 15 times. 
In a small Tay grilse of 2 lbs. \ oz. the measurements give 
15*9 times. 
These two grilse are exceptionally small, and have been pre- 
served by me on this account. Without any doubt the caudal 
peduncle is broad, but on inquiry I am informed by Mr Milne, who 
has had a wide professional experience as a salmon fisher both in 
Scotland and Ireland, that the fish of the Galway river “are 
thicker above the tail than the East of Scotland grilse. They are 
rougher altogether, fins and tail larger in proportion.” In spite, 
however, of this unusual depth of caudal peduncle, the number of 
scales, counted forwards and downwards from the posterior margin 
of the adipose fin to the lateral line, is on each side 12. This, in 
my view, is by far the most reliable test by which to distinguish 
between salmon and sea trout, the former having almost invariably 
11 or 12, the latter having almost invariably 14 or 15 scales in 
the line indicated. The present specimen, therefore, in spite of 
its sea-trout-like caudal peduncle, has the salmon number in the 
matter of scales. Mr Milne reports that on capture the scales 
came off very freely. This accounts for the rather patchy appear- 
ance of the side in the photograph of the fish which accompanies 
