346 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
just above the spider’s feet. This is illustrated at Fig. 157, page 167. 
The same effect is produced by the stay lines which are attached above, 
and which often draw up parts of the surface, as at Fig. 337, into little 
domes. We might almost think of these as the germinal form of the 
tube as it is seen in the Lineweaving species. But still more distinctly 
we may see the habit naturally engrafted upon such an interesting species 
as Theridium zelotypum or Theridium riparium, whose beautiful nesting . 
habits are described in Chapter XVIII. In these species the inside lining 
of the nest of gathered sticks and rubbish is a distinct tube, which is 
sometimes prolonged beyond the mouth of its den. 
Indeed, whenever a Theridioid spider takes its place beneath a leaf or 
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Fie. 337. Snare of Linyphia costata, showing tent like elevations. 
other shelter, as it often does, especially under stress of continued bad 
weather, it is sure to spin above and around its abdomen a little 
conical mass of lines, which, by the pressure upwards of the an- 
imal, is compacted or beaten into a concave form. If the weather 
continue unfavorable, or the spider is undisturbed for a considerable length 
of time, this little rudimentary tube will gradually make encroachments 
upon the leafy shelter, and will be prolonged outward and downward. 
Now, when the sun comes out and invites anew to web spinning, it is in- 
evitable that the snare will be spun just beneath or close in the neighbor- 
hood of this tube like shelter. Thus it becomes easy to explain the ap- 
pearance of a tubemaking habit, not only in Lineweavers, but in Orbweavers 
Growth of 
a Tube. 
