Ra 
From these it will be noticed that the curves for the broods of ’93 and ’95 are 
almost identical, with i5 as the prevailing number of spines, while the brood 
of 94 stands quite distinct, with 14 as the prevailing number. The mean for the 
broods of ’93 and 795 is 14.65 and 14.69 respectively, and for the brood of ’94, 14.39. 
A comparison of the fins of 500 specimens, including an equal number of each 
sex, from Tippecanoe Lake, of the brood of ’95, taken the same summer with 500 
specimens of both sexes of the brood of ’96 taken the same summer, shows them 
to be almost identical in the anal rays and dorsal spines, as can be seen from the 
counts given in Table II. Thus, in the anal fin we have 10.96 and 11.02 for the 
mean in the two broods; 58 and 59 are the percents of specimens having the pre- 
vailing number, ll rays. Around this the variation is symmetrical in both broods, 
The means for the dorsal spines are 14.06 and 14.22. The per cent. of specimens 
having the prevailing number, 14, are 62.20 and 62.80. The variation from this 
number is nearly the same. 
These two broods, however, show quite a difference in the dorsal rays, as 
shown by the mean and by the nature of the variation. The mean number of rays 
for the brood of 795 is 15.57 and 15.90 for the brood of ’96. In Fig. 4 are given 
the curves for the dorsal rays and Table XIII contains the details of the counts. 
In the curyes the continuous lines represent the brood of 795. 
Both broods have 16 as their prevailing number, 49.20 per cent. in the brood 
of ’95 and 55.20 per cent. in the brood of ’96 having this number. In the brood 
of 96 there is an approximation to a symmetrical variation around this number, 
while in the brood of ’95 the number of specimens, 40.80 per cent. having the next 
lower number, 15, is almost as great as that of 16. 
TABLE XIII. 
"95°, "965. 
Per cent. of specimens having 10 dorsal rays...............--}sseeeeee 0.20 
Per cent: of specimens having 11 dorsal rays. .....0..4..--.-.|5.4.++59| eee 
Per cent. of specimens having 12 dorsal rays................. 0.20) || :\cindenneee 
Per cent. of specimens having 13 dorsal rays.................[.005. 2. .|| caren 
Per cent. of specimens having 14 dorsal rays................. 4.00 1.60 
Per cent. of specimens having 15 dorsal rays................. 40.80 24.80; 
Per cent. of specimens having 16 dorsal rays................. 49.20 55.20 
Per cent. of specimens having 17 dorsal rays................. 5.20 16.80 
Per cent. of specimens having 18 dorsal rays............. ae 0.40 1.40 
Per cent. of, specimens having 19 dorsal rays. : i.) ae. - 0 4-1-2 ls oe +a) eee 
Per cent. of specimens having 20 dorsal rays................. 0.20" | xno 
