— 127 — 
applies, that they are largest in the vicinity of the lateral line, near a point opposite the 
fore end of the third dorsal and second anal fins. Table I shows the size of the scales 
in the “central” longitudinal row, from the upper corner of the gill opening to the cen- 
tral rays of the tail fin, with the relation of the central zone to the whole scale, which 
is measured in two dimensions, 4 and #, as shown in Fig. 84. 
Table 1. 
Coalfish 45.3 cm. Cod 54.0 cm. 
Nr. a B Go «|, Eb Nr. a B 9 Bo 
a fe} a el 
] = = I 
10 en 123 Male Ml) WBE 45 66 122 nl || 88 
ZN eae TT EN ge! © | 7 | WS | wm 
30 es IQS | 22 | © 55 68 118 69 | 67 
40 sve || 1240) | 208 | GEL || 0 || 8 125 12 | 69 
@ |... | ies | so. | 8 | Gy | we 9 | WS] D 
60 aco | 130 on | 35 70 82 145 71 68 
70 mae || Aloe Coe ale tod 75 90 153 67 66 
SOM ead AT Bike, 20-88 8D | Sy | 1 | & 68 
SOM RON EEE PENSE 8 | 104 | er | @ 
100 san | 169 en 31 9021 912162 71 75 
WO | os. 152 nee, 10:89 95 | 94 162 69 69 
120 oa 155 ue 31 100 98 | 163 71 67 
130 | 1S IR 31 105 | 93 | 160 65 67 
120) soe | eB BRENNT || | 
150 ee | eee | eos | 
160 | © | 32 | 
Average = atts 34.4 Average 69.8 | 68.0 
Index of variation m= Fe 4.7 lo | Index of variation m=] 3.8 Jo | 240 
From Table I, we see that the size of the scales increases and decreases somewhat irre- 
gularly backward over the central row. 
‘If we now consider, in the same manner, a cross row of scales from the lateral line 
downwards, we find the results shown in Table 2. 
“As will be seen from this table, there is always the risk, in calculating the 
length of the fish in its first winter, of an error of up to 5 % or more, corresponding to 
an error of up to 8inm., which may, in exceptional cases (1 of 360), theoretically, amount 
to three times this figure, or 2.4 cm. 
“Even this possible error need not, however, be any serious hindrance, its influence 
on the average of a large number of individuals being very slight. The calculated ave- 
rage length of 100 fish in their first year will thus be subject to an extreme error of 0.24 
cm., when the average is taken at 15 cm. And if, instead of the microscope, a projector 
be used, then this error, (due partly to inaccuracy of measurement and partly to ir- 
regularity of growth) will as a rule be reduced by one half. 
“The proportion existing between the dimensions of the scale and those of the fish 
