58 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



FIG. 56. Flossy ribbon braces of Uloborus. 



near the hub where the spider waits, is commonly quite long enough to 

 allow the active creature to reach and secure her victim, when capture is 

 desirable. When for any reason capture is not desirable or prudence sug- 

 gests caution, the nearness of the spider to an insect thus arrested on the 

 naked radii brings it within her vision, which at the best seems to be 

 limited. On the contrary, insects who strike upon the outer margin are 

 not only detained by the viscid beads, but made comparatively harmless. 

 5. The Free Zone gives the further advantage of allowing the spider 



easy access to the under part of the 

 snare, a convenience which is some- 

 times important. It is perhaps worth 

 noting here that vertical snares which 

 have an open hub appear quite com- 

 monly to have no free zone, that 

 part of the web being occupied by 

 the notched zone prolonged to the 

 inner boundary of the spirals. 1 Thus in either case, although by an inter- 

 esting variation in spinning habit, the way is left open for the spider to 

 pass from one side of her orb to the other. I have watched with great 

 interest the agility of a large Argiope in swinging herself from one side 

 of her shield to the other when threatened by danger. I could always by 

 demonstrations with finger or pencil cause her to change sides. This was 

 done invariably by crawling through the free zone. The space seemed over 

 small to give passage to such a large creature, but the elasticity of the 

 threads readily permitted the transfer, 

 which was made with remarkable deft- 

 ness and dexterity. 



The chief purpose of the Notched 

 Zone seems to be to strengthen the 



web, and particularly to brace 



Notched j i, u - A - 1 j-- 



z and hold in position the radii 



before the spirals are wrought 

 in. My observations indicate that the 

 notched spirals are invariably woven 

 in before the beaded spirals. The outer 

 or diverging ends of the radii being supported by the Foundation lines, 

 the inner or converging ends by the notched space, the spider begins to 

 lay in her foundation spirals from the inner margin of the spiral space, 

 working toward the circumference. Thus her operations are conducted 

 somewhat after the architectural modes of a human builder erecting a 

 large scaffolding. 



1 I make this statement with some qualifications and cannot positively say that it is true 

 of all snares with open hubs. That it is with many I know. The point is one for further in- 

 vestigation. 



FIG. 57. Flossy circular braces of Uloborus. 



