EVIDENCES OF A DIFFERENTIAL DEATH RATE, ETC. 159 
Thus, among 2748 young, mostly 10 to 13 inches long, 915 
were females and 1833 were males (66% males) while with 
a group of 422 fish 34 to 50-plus cm. long, 306 were females 
and 116 were males (27% males.) 
d). THE SALMON, Salmo salar L. 
MASTERMAN (1913) made a study of the salmon with 
especial reference to age-determination by study of the scales. 
He found that the male sex predominated numerically in the 
early years and (MASTERMAN, 1913a) that this predominance 
is lost in the higher age groups, and is replaced by that of the 
females. 
MENZIES (1916) has also shown a lower percentage of 
males with increase in age. Thus, in a group of 1294 year- 
lings, the sex-ratio was 100 females to 71 males, while in a 
group of 347 two-year-olds, the ratio has been reduced to 100 
females to 43 males. MENZIES’ (1921) data also, though 
somewhat confusing, bear out his earlier conclusion. He 
found that in the salmon of Thurso Bay, about one-third of 
the total catch were males. The different age-groups, how- 
ever, varied considerably. Thus, among the “grilse” (1-plus 
years) group the average percentage of males for the whole 
season was 57, while for the “small summer fish” (2-plus 
_ years) group there was an average percentage of males of 
only 21. 
e). THE SMELT, Osmerus eperalanus L. 
MASTERMAN (1913a) by the dissection and study of 217 
fish ascertained that in this species the males predominated 
in numbers in early years: a predominance that is lost in the 
higher age-groups and is replaced by that of females. Thus, 
the oldest and largest fish were found to be females. From 
this he concluded that the probability of life is less in the 
male than in the female sex. 
f). THE DOGFISH, Spinax niger. 
PUNNETT (1904, p. 321) by the microscopical examination 
of the gonads of 308 dogfish embryos found the sexes to be 
approximately equal in numbers at birth. (This conclusion is 
strengthened by the fact that in the three different years— 
