108 
BULLETIN OF THE BUREAU OF FISHERIES 
These tiny scales were sampled by scraping a scapel along the side of a specimen 
and wiping on a slide. By so doing, scales were taken from a large part of the body 
and they included the smaller ones along the back and near the median line of the 
belly as well as the larger ones along the middle of the side. The smaller scales had 
fewer circuli than the larger, so that the count obtained from any one fish might run 
from 2 to 5, 4 to 6, 5 to 8, etc. A variation of this sort is shown by Meek (1916, p. 
219), who records cod of about 5.8 centimeters taken in July, with 0 to 2 circuli; and 
in October, fish 6.9 centimeters long with 2 to 4 circuli, and fish 11.1 centimeters 
with 7 to 9 circuli on their scales. 
The fish listed in Table 39 were taken during several collecting years. In general, 
the smaller ones were caught in April and May and the larger in June and July. 
Accordingly, southern Massachusetts cod 4 or 5 inches long in the summer have 
about 8 to 12 circuli on their scales. Such fish are less than 1 year old, so that by the 
time a full year has been completed the number of circuli should be appreciably greater 
than 12. Young cod caught between Cape Cod and eastern Maine had nearly the 
same circulus count, with respect to their size, as did the southern Massachusetts cod, 
but as we had only 17 young fish from Maine (50 to 120 millimeters long) taken not 
from April to July but from August to September, a fair comparison could not be 
made. 
Five cod caught on Nantucket Shoals in October, selected at random, had the 
following circulus count on their scales: Length of fish 156 millimeters, scale circuli 
21 to 22; 168 millimeters, 21 ; 171 millimeters, 21 ; 189 millimeters, 21 ; 197 millimeters, 
19 to 21. All these scales had only one zone of growth, but as they were caught well 
into the fall they probably were nearly 1 year old. Another specimen 178 millimeters 
long, taken with the above ones, had 13 closely spaced circuli in the first zone of scale 
growth, followed by 5 widely spaced circuli. This fish apparently hatched in a 
different season than the others. 
It is not understood why the 156 millimeters cod had as many circuli as the 198 
millimeter fish, for whether they were the same age, with one growing faster than the 
other, or whether they grew at the same rate, with one being older than the other, 
one might expect the larger fish to have the more circuli on its scales. 
According to the scale growth of the few 156 to 197 millimeters cod, presumably 
nearly 1 year old, taken off southern Massachusetts, we could expect that cod living 
in this region, from the fry to adult stage, should have about 20 to 22 circuli on their 
scales within the first zone at the end of about one complete year of growth. To 
determine this, the scales of adult Nantucket cod were examined. The first growth 
zone on some of these scales, no doubt, represented somewhat less than a full year’s 
growth and on others somewhat more, but, as a large sample was utilized, the average 
must have been just about between. 
