148 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Orbweavers. Each concentric of the scaffolding, which is marked by the 

 arrows in the figure (Fig. 138), makes a marked division between the in- 

 termediary spirals, which are thus divided 

 into groups or bands, adding much to the 

 peculiar form of the snare. 



Wilder states * that the free sector or 

 space uncovered by beaded spirals in the 

 snare of Nephila, in natural site is equal 

 on an average to about one-sixth the sur- 

 face of the orb. He, however, gives a 

 drawing of a web made by a spider in 

 captivity upon a circular wire frame, which 

 has a free sector equal to two-thirds of the 

 orb. 2 (Fig. 139.) No doubt this abnormal 

 form was due to the artificial conditions 

 FIG. 139. snare of Nephila, woven on a wire under which the spider plied her industry. 



hoop. (After Wilder.) ^ . -. . , . , , . . . , . 



Prof. Wilder is sufficiently explicit in his 



description to allow us to present the diagramatic or restored web, Fig. 

 140, as approaching the characteristic form in natural site. 3 It thus closely 

 approximates that of Epeira triara- 

 nea and Zilla. The spirals do not 

 form complete circles, but are looped 

 across the radii, in a manner already 

 described, and in spinning them the 

 spider does not move around the 

 web, but returns upon her course 

 from one side to a corresponding 

 point on the other. The web thus 

 made is strong enough to support 

 a light straw hat when hung up- 

 on it. 



Gosse speaks of the immense 

 snares of Nephila as one of the 



obstructions to free travel 



Jamaica ^ n ^ Q WOO( j s o f J ama i ca . 



Nephila: 



Gosse. These, he says, are in- 

 fested with the great long 



" FIG. 140. A diagramatic snare of Nephila, composed from 

 bodied Spider With brush tufted the descriptions and sketches of Prof. Wilder. 



1 Proceedings American Association, 1873, page 265. 



2 This has led Emerton, Structure and Habits of Spiders, page 66, to the erroneous state- 

 ment that her snare " consists of loops running round about quarter of a circle." 



3 Prof. Wilder, in his paper, Proceedings American Association, 1873, page 272 ; also 

 Galaxy, page 111, 1869, and on the Triangle Spider, Popular Science Monthly, page 653, 

 1875, gives an outline cut of Plumefoot's orb, which corresponds with that of Fig. 140. 



