( 500 ) 
years, regularly affords a good mark to distinguish young salmon 
and trout as far as I could ascertain. In the scale of the salmon 5 
to 6 and no more of the very first formed rings are quite closed; 
their shape is oval and they are surrounded by the larger ones all 
of which have the shape of U’s. With both species of trout it seems 
to be the rule, however, that of .the rings formed on the scale in the 
first years a much larger number present themselves as quite closed 
rings. In the seatrout (fig. 23) this is the case with the rings formed 
in the first year especially, in the brooktrout (fig. 22) a very large 
proportion of the rings of the second year show this particularity: 
sometimes with a few exceptions all the rings of these years are so 
formed. So the fact that there is a greater relationship between 
brooktrout and seatrout (called Scotch salmon by our fishermen) than 
there is between the salmon and one of these trout, which was 
pointed out by Day 1 ) years ago and which I emphasized myself on 
a former occasion 2 ), by the structure of the scales is confirmed in 
a very striking way. 
EXPLICATION OF THE FIGURES. 
N.B. All the figures are drawn with the camera, so there can be no question 
regarding the exactness of the shape and the main lines; the lines of growth, 
however, were free hand drawn, their number as much as possible in correspond¬ 
ence with the object. All figures are drawn with the free end of the scale above. 
This end is directed backwards on the fish. 
PLATE I 
Fig. 1-13: Scales of salmon, which have not left the freshwater as yet . 
Fig. 1—10: Salmon of the first year. 
Fig. 1. Scale from the side of a little salmon of 5.5 cm., caught Aug. 12th, 
1909. Magnified 148 diameters. 
Fig. la. Same scale, magnified 30 diameters. 
Fig. 2. Scale from the side of a little salmon of 4.8 cm., caught end June 
in the so-called Brook of Huningen. Magnified 30 diameters. 
Fig. 3, 4, 5. Scales of a little salmon of 9.1 cm. from Marxzell, September 
1909, from different places of the surface of the body. Magnified 40 diame ers. 
Fig. 3 taken a little behind the head. 
» 4 „ from the side, above the lateral line. 
, 5 „ about the height of the anal aperture, beneath the late ^^ 
Fig. 6. Scale from the side of a little salmon of 5.1 cm. from Marxzell, Sep¬ 
tember 28th, 1909. Magnified 40 diameters. 
*) Fr. Day, The Fishes of Great Britain and Ireland. 1880—84. . 
2 ) Hoek, La truite de mer du Rhin. Tijdschr. d. Ned. Dierk. Vereen. 
1892. p. 243. 
