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IOWA ACADEMY OF SCIEXCE Vol. XXV, 191g 



place where there is an abundance of moisture and plenty of 

 flies to catch. They make no attempt at symmetry, as is done 

 by most spiders, yet from a position usually near the top there 

 radiate out to the other parts of the web a few lines that will 



Fig. 32. — Her most coni'inon catch. Female snaring a house fly ; X4. 



enable the female to perceive even slight vibrations in most parts 

 of the web. 



When a victim, usually a fly, gets tangled in the web the 



