22° The American Naturalist. [January 
Locality. — Elevation. Average number of anal rays. 
Umatilla, 300 19 
Wallula, 326 9 
Pasco, 375 20 
Lewiston, 750 20 
Pendleton, 1070 16 
Yakima, 1078 17 
Colville, — 1200 16 
Potlatch, _ 1200 19 
Revelstoke, 1475 15 (only one specimen). 
Little Spokane, 1850 15 
Spokane, 1910 16 
Hangman Creek, 1910 17 
Pend d’Oreille, 2000 16 
Small Creek, 2100 17 
Payette, 2150 18 
Snake River, 2150 20 
Caldwell, 2812 18 
Golden, 2550 16 
La Grande, 2550 16 
Flathead, 3100 17 
. Brown’s Gulch, 5344 16 
Summarizing this: Below 1000 feet the averages are 19 and 
20; above 1000 feet only one averages 20, only one reaches 19, 
two reach 18, four have 17, seven have 16, and two have 15. 
These figures “ are not so unanimous in their indications” of 
a decrease of rays with an increase of altitude as those for the 
Frazer system. But the lower locality generally possesses a 
high number of rays. Here, where we have data from many 
widely separated branches, a close variation of rays, with 
altitude, is not found. Local issues have modified national 
tendencies among these fishes in the Columbia system. 
Among the locality curves (figures 4 and following) the ideal 
curve is most nearly approached at Caldwell. The variation 
from the average is here equally great in both directions; and 
the curve of the ascending variation is almost identical with 
the curve of the descending variation. Nearly as ideal condi- 
