COMPOSITE SNAKES AND SECTORAL ORBS. 



145 



web of the Orbitelarise ; or, shall we say, a tendency to run tangent from 

 its own typical form into that of the established type of Epeira? 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 iuterblending of spinning habit 

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

 the genus Epeira, Epeira 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 orb with the feet of the spider lodged 



Traphne jj^ }^g^ retreat above and at the side / /A of her snare. As a 



ana- Yv\>i, the end which is attached to 



several branches, obviously giv 



in the way of telegraphy. Sometimes 



will be observed near the feet of the spi 



the trapline. But generally 

 holds the single line within 

 Labyrinth s})ider, the trap 

 threads which diverge near 

 by the foot, and converge 

 the ordinary r«le 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. 

 assumed the rude outline of an hour glass 



Flfi. 136. Branched 

 trapline system of 

 Zilla. 



the hub divides into 

 ing greater facility 

 one or more branches 

 der, where she clasps 

 one fore foot reaches out and 

 the claws. In the case of the 

 line consists of a number of 

 tlie 2)oint where they are clasped 

 toward the liub, 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- 

 supported by another Y-shaped 

 At Fig. 135 the trapline has 

 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 

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

 grounds of A\'oodland Cemetery. The question, of course, naturally arose. 



