14 THE ROYAL SOCIETY OF CANADA 
of fifteen in number. In the fish under consideration the nucleus was 
surrounded by some thirty-nine or forty narrow lines, which passed 
rather gradually into a zone of broad lines representing summer growth. 
Following these came a typical zone of narrow lines representing a 
winter check, then a zone of broad summer lines, then a second zone of 
narrow lines and finally a few broad lines representing the summer in 
which the fish was on its way to the spawning ground. Judging from 
the evident winter checks one might suppose that this fish was on its 
way to the spawning grounds in its third summer, but this would not 
account satisfactorily for the excessive breadth of the zone of narrow 
lines immediately surrounding the nucleus. This, I believe, may be 
properly explained on the supposition that this zone represents two 
years spent in fresh water, the two winter check zones representing not 
the second and third winters of the fish’s life, but the third and fourth. 
In other words, this fish was one which went to the sea as a yearling 
(Babcock) in the second spring after hatching. 
As stated in the introductory account of the life-history a number 
of undersized but fertile male fish return to fresh water. These grilse 
are about two-thirds the size of the typical adult fish, four examples 
that I obtained at Esquimalt measuring respectively 49 em., 45 em., 
46 em., and 47.5 em. The age of these fish is in doubt, some placing 
them at two years and others at three, the latter estimate being based 
on the belief that in the Fraser River the grilse are more numerous in 
the year preceding a “big run” than at other times. A study of the 
scales of these fish shows conclusively that they are two years old. 
Around the nucleus (Plate IV) is the typical zone of narrow lines re- 
presenting the winter in fresh water; then comes a zone of broad lines 
representing the first summer’s growth in the sea and then a zone repre- 
senting a winter check. Beyond this is a zone of broad lines represent- 
ing the second summer spent in the sea; this zone however is not fol- 
lowed by a winter check zone, but extends to the margin of the scale, 
indicating that the fish was taken in the second summer of its existence,,. 
This arrangement of the lines occurs in each of the four grilse examined, 
and, making allowance for the small number of fish examined, it may be 
concluded that the grilse are typically two year old fish. 
THE OTOLITHS. 
Of the two otoliths I have given attention only to the larger, the 
sagitta, and after trying several methods finally adopted that of clearing 
the bone in oil of cloves and examining it as an opaque object. This 
gave a picture slightly clearer even than that obtaining when xylol was 
used, as Fryd! proposed. 

ILoc. cit. 
