202 



AMEllICAN SPIDERS AND THEIR SPINNINGWORK. 



Fig. 196. Ray spider. Action when an 

 insect is taken. S, spider ; In, insect. 



Theridiosoma, as represented at Fig. 194, or again, as shown at Fig. 195, 

 we observe that if the fore feet, 1, 2 (Fig. 194) are released suddenly from 

 the trapline, T, the whole body shoots backward, although still toward the 



snare, as with Hyptiotes. This was the ac- 

 tion which I observed. 



The determination was finally accomplished 

 by first carefully sketching the arrangement 

 of the basket stretched between the feet (2, 

 3, 3, 4, 4, Fig. 195). With this chart in one 

 hand, and in the other hand a magnifying 

 glass focused upon the feet, I watched until 

 favored with several successive and unsuc- 

 cessful springings of the net. As the spider 

 only leaves her seat when she thinks that an 

 insect is well entangled, and again bows her 

 net by pulling on the trapline if no prey be 

 ensnared, the above conditions enabled me to 

 compare my chart of the basket, with the 

 basket itself as seen under the glass. I found 

 that the outlines on the paper and the lines under the animal's feet ex- 

 actly corresponded. There had therefore been no change in the relative 

 positions of the hind feet, mandibles, and palps, and perhaps also of the 

 second pair (2) of feet. There had been an actual (not seeming) motion 

 of the body with and in the direction of the snare, and this had been 

 caused by releasing the first pair of legs (1) from the trapline. The only 

 actual motion, therefore, was the slight hitch forward produced by the 

 elasticity of the axes of the rays and other parts of 

 the snare behind the aranead. 



The importance of this determination seems greater 

 from the fact that I had at first concluded that the 

 Ray spider actually operated her snare by sections. 

 That is, instead of springing the whole orb at once, 

 as above described, she simply sprung the ray struck 

 by an insect, by unclasping the foot holding the axis 

 of that ray. Thus, ray ii, Fig, 195, would be sprung 

 by releasing the axis of ii from the third foot, No. 

 3. This is probably not done when the snare is in 

 comidete form (as at Figs. 187, 189, 190), but I be- 

 lieve that it is done when the web has been par- 

 tially destroyed, and is reduced to two rays or sec- 

 tors, as at Fig. 197. 



The fragmentary condition of the Ray si)ider's web after contact with 

 insects has already been referred to. The snare is gradually obliterated, a 

 conclusion to which the spider herself very curiously contributes. When 



Fig. 197. Ray spider's snare 

 after usage in taking prey. 

 The spider is at the centre, 

 holding the rays " locked." 



