[mcuurrica] LIFE CYCLES OF THE PACIFIC COAST SALMON 21 
of the same size were 12.0 mm. and 6.0 mm. The size of the ossicles 
does not increase regularly with the length of the fish, but on the whole 
the larger fish have the larger ossicles; in a fish measuring 108.0 em. 
the length and breadth of the sagitta were respectively 15.0 mm. and 
5.5 mm., and in one of 112.0 cm. they were 16.5 mm. and 6.5 mm. In 
a grilse Spring measuring 57.5 cm. the measurements of the sagitta 
were 8.5 mm. and 4.00 mm. It may be mentioned that the proportion 
of the breadth to the length of the ossicle seems to differ regularly in 
the two species thus far considered, it being in the Spring Salmon 
either one-half or less than that, while in the Sockeye it is always 
greater than one-half. 
As to the markings on the ossicles, what was said concerning those 
of the Sockeye applies equally to those of the Spring. A central 
nucleus is always quite distinct and surrounding this a usually well 
defined zone represents the growth in fresh water. Peripheral to this 
one sees with more or less distinctness in: adult fish three clear lines or 
bands, representing the growth during the three winters spent in the 
sea, and in grilse a single line or band, representing the single winter 
spent inthesea. The story told by the ossicles is therefore confirmatory 
of that revealed by the scales; but it is not presented with as great 
clearness or with so much attention to detail. In the ossicle from 
the 91.5 cm. fish, however, shown in text-figure 5, it was possible to 
detect the “check” band corresponding to that shown by the scales 
in the second summer in the sea, although no trace could be seen of that 
occurring in the first summer. 
THe DoG SALMON, O. keta (WALBAUM). 
At the time of my visit to the Pacific Coast the Dog Salmon had 
hardly commenced their run and consequently it was not possible to 
obtain any considerable number of them. I was fortunate enough, 
however, to secure four individuals, two at Esquimalt and two at the 
Claxton Cannery. All four were adult fish, one measuring 64.0 em. in 
length, one 69.5 cm. and the other two 74.0 em. | 
THE SCALES. 
In three of the four individuals the arrangement of the scale 
markings (Plate VIII.) was essentially the same as in the Sockeye and 
Spring Salmon, a central nucleus surrounded by a zone of fresh-water 
lines, and this by four zones of summer growth in the sea, interrupted 
by three winter “check” zones. The life cycle in this species is, accord- 
ingly, also one of four years. 
