56 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Free 

 Zone. 



FIG. 52. Sheeted hub of Argiope. 



overlays the radius longitudinally for a minute space at the point of 

 crossing. The precise effect of this arrangement may be produced thus : 

 Stretch a cord tightly ; then take a second cord, loop it by one twist 



around the first, and draw its two loose ends 

 in opposite directions. The appearance of these 

 notches is shown at Fig. 53. 



The Free Zone (FZ, Fig. 49, see also Fig. 

 50), the third division of the Central space, is 

 that portion of the orb which, for the 

 most part, lies between the notched 

 zone and the spirals, and consists 

 simply of the radii without any crossing lines. 

 Its outer boundary appears always to be marked 

 by the last or innermost of the foundation 

 spirals. Black wall 1 objects to the statement 

 of Kirby and Spence concerning a free zone 

 as characteristic of geometric webs, that this 

 is true of but one species. But the greater 

 part of our vertical orbs have the free zone. 

 It seems strange that Black wall 2 should speak 

 of the nets w r hich are destitute of the free zone 

 as, having the centre entirely closed up (meshed 

 hub), for certainly in America the orbs spun by the genus Epeira, which 

 are by far the most frequent, have both the closed centre and the free 

 zone, almost invariably. (See Fig. 50.) I must doubt the accuracy at 

 this point of the distinguished observer, and the 

 doubt is confirmed by my limited observation of 

 the spinningwork of British spiders. 3 

 , , The economy of the Central Space in 

 Space. its severa l parts must be a matter of 

 conjecture, but there are some good 

 grounds for the following opinions: 



1. It must be noted, first, that no part of the 

 Central space has viscid beads. This permits the FIG. 53. Notched spirals (greatly en- 

 freer motion of the spider around the centre 



without liability of entanglement upon her own snare. She is, indeed, 

 able to run over the beaded spiral space with apparent impunity, yet her 



1 " On the Construction of the Nets of Geometric Spiders," Zoological Journal, Vol. V., 

 1832-4, page 184. 



2 As above, page 185. 



3 Mr. Cecil Warburton writes me from Southport, England, that the snares of Meta 

 segmentata are distinguishable at a glance from those of most ronminii Kuglish Epei'roids, 

 as Zilla atrica, Epeira diadcinata. Ep. quadrata, etc., by the presence of a notched zone 

 and the absence of a meshed centre. Kvidmtly, his observation of the common species 

 showed a closed centre. 



