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ENGINEERING SKILL OF SPIDERS. 219 
or, perhaps, had been purposely massed by the spider. However that may 
be, the ball was utilized as a nest; its centre had been pierced, a spher- 
ical cavity formed by silk lining the interior, which was entered by a 
circular door bound around the edge by spinningwork. This quaint dom- 
icile was pendent from one of the strong upper foundation lines, and 
herein Strix rested, while the emmet carpenters worked away above her, 
continually dropping chips over the roof of her nest and the orb be- 
neath, until one side of the snare was quite covered with them. In 
this case the position of the nest, as well as its form, was exceptional, 
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Fie. 207. A meadow orbweb braced to an overhanging branch of a tree. 
as the nest site of Strix is well nigh invariably beyond the limits of the 
web, sometimes, indeed, several feet. In these points the spider was evi- 
dently led to an intelligent variation of her nest building by circumstances. 
(Fig. 205.) A series of interesting illustrations of the same elasticity of 
habit in the nesting industry of the Furrow spider may be found in the 
subsequent chapter on Nesting Habits, and might, with almost equal 
propriety, have been introduced here. 
Another case of adaptation may be cited, without impropriety, as a good 
example of Epeiroid engineering. While walking through the pine woods at 
the head of Deal Lake, New Jersey, I found a narrow path blocked by a 
