COMPOSITE SNARES AND SECTORAL ORBS. 



145 



web of the Orbitelarise ; or, sliall wc say, a tendency to run tangent from 

 its own typical form into that of the established type of E})eira? On one 

 small bush, where perhaps a dozen Zilla atricas were domiciled, I found 

 no less than four orbs with completely rounded webs. In one of these, a 

 very rare circumstance indeed, I found that the trapline occupied a sector 

 below the median line of the web. In this interblending of spinning habit 

 Zilla shows the peculiarity already noted in the closely related species of 

 the genus Epeira, E})eira triaranea. 



This colony afforded some very interesting illustrations of the strong 

 tendency to variation in the manner of forming the trapline. Ordinarily, 

 as has been shown, the trapline of orbwebs consists of a single cord, which 

 connects the hub of the orl) with the feet of the spider lodged 



Trapline 

 Varia- 

 tions. 



in her retreat above and at the sid 

 rule, the end which is attached 

 several branches, obviously gi\ 



in the way of telegraphy. Sometimes 



will be observed near the feet of 



the trapline. But generally . 



holds the single line within 



Labyrinth spider, the trap 



threads which diverge near 



by the foot, and converge 



the ordinary rule in the gen 



is probably the one most 



series of drawings presented 



depart from this habit. Fig. 



trapline with a number of 



of the spider at S, the whole 



die of the line, T, and being 



line still nearer to the hub. 



Fi(i. 136. Branched 

 trapline system of 

 ZUla. 



of her snare. As a 



the hub divides into 



ing greater facility 



one or more branches 



der, where she clasps 



fore foot reaches out and 



the claws. In the case of the 



line consists of a number of 



the point where they are clasped 



toward the hub, and thus reverse 



us Epeira. The single trapline 



commonly used by Zilla, but the 



will show how widely she can 



134, for example, shows the 



diverging lines toward the foot 



system forking about the mid- 



sup})orted by another Y-shaped 



At Fig. 135 the trapline has 



assumed the rude outline of an hour glass. Five or six deltations grasp 

 the meshed hub, and these lines converge about the middle of the trapline 

 system, from which point they diverge toward the spider's nest and the 

 surrounding leaves, upon which the snare is supported. The feet of the 

 spider at S are extended beyond the leafy nest, and grasp at least two 

 lines of the system. Fig. 136 shows still further divergence from the 

 original type. Here the hour glass, if I may continue the figure, appears 

 to have been cut into two, and the ends well separated by a bent line, in 

 the midst of which is a triangular patch swung to adjoining leaves. The 

 two fore feet of the proprietor are thrust from her tubular nest and grasp 

 the principal diverging lines of her system. 



I have observed similar arrangements in the trapline system of Epeira 

 domiciliorum whose orbs were swung upon a barbed wire fence inclosing the 

 grounds of ^^^)()dland Cemetery. The question, of course, naturally arose, 



