56 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



overlays the radius loiigitiulinally 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. BlackwalP 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 

 })art of our vertical orbs have the free zone. 

 It seems strange that Black wall ^ should speak 

 of the nets which are destitute of the free zone 

 Fi.,.52. Sheeted hub of Argiope. .^^ havlug 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 



tlie spinningwork of British spiders.^ 



Tlie economy of the Central Space in 



its several 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 fkj.ss. Notched spu-ais (greatly en- 

 freer motion of the spider around the centre ^'^'^^ ^' 

 witlioul liability of entanglement upon her own snare. She is, indeed, 

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



' " On tlie Construction of the Nets of Geometric Spiders," Zoological Journal, Vol. Y., 

 1832-t, page 184. 



^ As above, i)age 185. 



' Mr. Cecil Warburtoii writes me from Southport, I'^ngland, that the snares of Meta 

 segmentata are distinguisliahle at a glance from tliose of most common English Epei'roids, 

 as Zilla atrica, lOpcira diatlemata, l'>p. (|nadrata, etc., hy the ])rcscnce of a notched zone 

 ami llii' alisence of a meshed (;entrc. llv 'ulcntly, liis ol)S('r\atioii of [\\v coniiiion sjiccies 

 sliowcd a closed centre. 



Use of the 



Central 



Space. 



