GENERAL CHARACTERISTICS OF ORBWEAVERS' SNARES. 59 



Certain species (indeed, the habit has its representatives among several 

 genera) further strengthen the notched space by a close, plain band of 

 white silk, which ordinarily extends between two radii, along the perpen- 

 dicular diameter upward from the hub to the spiral space. (Fig. ">4.i 

 Sometimes also the ribbon reaches both upward and downward from the 

 hub, and takes the form of a scalloped band or thick winding cord. This 

 peculiarity prevails in all our indigenous examples of the genus Acrosonia, 

 and is also quite characteristic of the exotic species of the same- 1 genus. 

 Our beautiful and familiar representatives of the genus Argiope I A. cophi- 

 naria and A. argyraspis AValck.) 1 have the same habit. (See Figs. 5c 



Some species, as frequently Argiope argyraspis, add to this perpendicular 

 ribbon, on either side thereof, one or more semicircular zigzag cords, which 

 further tend to strengthen the central part of the orb. Some species of 

 Uloborus have a similar habit, but also at times throw the cord entirely 

 around the notched space, making a series of circles. (Figs. 56 and 57.) The 

 perpendicular cords are sometimes extended above and below the notched 

 space, and terminate in serpentine folds, bulb shaped tufts, or tapering 

 points. They give a striking and beautiful appearance to the web, the 

 graceful lines, and thick, white, flossy texture showing in pretty contrast 

 against the radii and spirals. Examples of these peculiarities will be found 

 among the descriptions of characteristic webs. (See Chap. VI.) 



These bands and cords, besides probably serving as braces, are used by 

 the spider as supports when she hangs at the open hub. Acrosoma rugosa 

 will generally be found hanging by her hind pair of legs to the lower end 

 of the ribbon. 



1 Epeira fascia ta Hentz, and Argiope transver^a Eim-rtnn. 



