ob AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
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. Blackwall! 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 haye the free zone. 
It seems strange that Blackwall? should speak 
of the nets which are destitute of the free zone 
_as haying 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.* 
Bee The economy of the Central Space in 
Space. _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 fe. 53. Notched spirals (greatly en- 
freer motion of the spider around the centre Pe 
without liability of entanglement upon her own snare. She is, indeed, 
Free 
Zone. 
FiG. 52. Sheeted hub of Argiope. 
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 common English Epeiroids, 
as Zilla atrica, Epeira diademata, Ep. quadrata, ete., by the presence of a notched zone 
and the absence of a meshed centre. Fyidently, his observation of the common species 
showed a closed centre, 
