THE AMERICAN NATURALIST [Vol. LIII 



water by the surrounding trees. There, undoubtedly, is 

 less evaporation in a region of this character than is true 

 in those parts of the brook which are situated in regions 

 lacking both trees and shade and are thus exposed to a 

 high temperature and to the full effects of the summer 

 sun. Very similar facts were observed near Charleston, 

 Illinois, by Adams (1915, pp. 65, 66) in connection with a 

 small stream ifi a forested area. He makes the following 

 statement : 



In this connection 1 wi-li to ^tatc tliat the \\at('i--trider- 

 were found in far gi'catei' numbers, in the late s])ring, 

 summer, and early fall, on those portions of the stream 

 that flowed tlirougli the forested area. After several 

 years of observation, T have come to the conchision that 



