ARGIOPE AND HER RIBBOXED ORB. 



99 



Use of the 

 Shield. 



used. However, in one snare noted, Ijuilt within a lodge across the angle 

 of two walls, the zigzag was prolonged into a series of lines like the rounds 

 of a ladder, spun across the corner quite dowii to the floor. This was used 

 as a gangway, by which on one occasion, at least, the occupant descended 

 to the floor and thence escaped from the room. 



The entire system of spinningwork thus described, .shield and ribbons, is 

 often five inclies in length, and extends across the Free space, dividing it 

 into two nearly equal parts. The spider hangs at the centre upon 

 the shield which thus covers the lower part of her body. Her 

 legs are well extended, but the corresponding pairs, the two fore 

 legs and the two hind legs, are approximated so that these members are 

 arranged somewhat X-shaped. The feet, however, are usually turned out- 

 ward, the points of contact of the legs being at the tibia. 



The main purpose of the shield I believe to be protective. It certainly 

 may serve as a strong screen against attack of enemies from the under or 



ventral side of the animal. As a rule 



that side of the shield which looks 



outward from the site is occupied by 



her; but at tim^s the animal hangs 



also upon tlie opposite face, next the 



leaves or shrubbery. I have often 



seen an alarmed spider scurry through 



the open space from the outer to the 



inner face of the shield. Again, the 



spiders which on one day were found 



Fig. 91. ^f=^-;Y^;/«jP;- hanging to the inside of the shield, 



Fig. 92. The abdomen 

 dropped, and the mass 

 of lines gathered into 

 loops. 



ning the 



Spinnerets open and the ^yQuld bc SCCU cliuging tO tllC OUtsidc 

 conical mass of spin- ° " 



ningwork drawn out. Oil thc iicxt day ; aiid, again, some on one side and some 



The abdomen lifted. , , ^, „,, , • n t ici • x 



on the otlier. 1 have fully satisfied myselt by experiment 

 that a threatened danger will be avoided by placing the shield between her- 

 self and thc apprehended peril. This is done by a dextrous movoniont, part 

 swinging, part crawling, through the free zone. 



The central shield and zigzag lines are not of slow growth, but are made 

 immediately after the spinning of the web. The manner of spinning is as 

 follows : When the orb is finished in the ordinary way, as heretofore de- 

 scribed, the spider goes to the hub, cuts out the temporary central anchor- 

 ages which she puts into her mouth, and i)roceeds to weave in the 

 Manner of ^],j(,|,]_ She holds ou with her feet to the lines of tlie notched zone, 

 Qp. , , throws the abdomen upward and backward as far as convenient, 

 the spinnerets being flared or extended to their utmost width 

 instead of being closed upon each other. The threads, wliicli issue from 

 all the si)inning tubes in streams of delicate filaments, are, of course, attached 

 to the shield and drawn out by this motion and the action of tlie hind legs. 

 (Fig. 91.) The alxlomen is tlien dropped down against the sliield space, 



