630 THE AMERICAN NATURALIST. [Voı. XXXIX. 
eleven and twelve slits, and those with twelve and thirteen, these 
two together amounting to 10% of the total number. Dr. 
Ayers also says: “Of the eight 11-12 variation, where the 
position of the gills was noted, four had eleven gills on the right 
side, and twelve on the left, while the other four were just the 
reverse, with twelve gills on the right side and eleven on the 
left." On looking over the count of five hundred and fifty hag- 
fish that I made while at Pacific Grove, I find still greater varia- 
bility in the percents. 
No. of No. of Gills 
Individuals Left Right Percent 
I 10 11 48 
3 II 10 54 
123 II II 22.36 
25 II 12 4-54 
44 12 II 8. 
.325 i2 12 59.09 
7 12 13 1.27 
X IL 13 12 2.73 
7 13 13 1.27 
This larger count gives practically the same percentage of 
individuals with twelve gills on each side as do Dr. Ayers’s fig- 
ures, reduces that of those with eleven gills on each side about 
one fourth, increases the sum of the 11—12, and 12-13 variations 
from 10.4% to 16.5%, diminishes those having thirteen gills on 
each side from 2.2% to 1.27%, "and introduces a new variation, 
10-11 gills, this kind being .72% of the total number. This last 
variation makes direct connection with the Chilean variety with 
ten gills on either side. It will be noticed in my figures that 
in the three uneven variations, 10—11, II—I2, 12—i3, the total 
number of individuals having the larger number of gills on the 
left side is sixty-two against thirty-three, almost two to one. 
This point will be discussed a little later. 
The table following combines the records of Dr. Gilbert and 
Dr. Ayers with my own. 
