648 THE POPULAR SCIENCE MONTHLY. 



them to a cylinder, the two colors were wound separately from the 

 living spider. Thus far, however, I have failed to ascertain their dis- 

 tinction with this species. So my figure and description may not be 

 correct in assigning to the anterior pair the duty of supplying the in- 

 terradial lines. 1 However, it seems probable that the process is as fol- 

 lows : One or more pairs of the spinners are first pressed together and 

 then separated. This draws out the silk as a band connecting their 

 tips. By keeping them apart, and repeatedly carrying the calamistrum 

 backward across their tips, the lines from each of the two mammulae 

 in one pair are kept separate until thoroughly dried. When the line is 

 completed and drawn taut they remain distinct, but very near together. 



We are now ready to observe the way in which the spider employs 

 the organs above described. Let us suppose that the framework of 

 the net is completed, and that the first or longest interradial line (Fig. 

 8, I') has also been made. Instead of beginning the second interra- 

 dial at S"", she begins at 4 ; and instead of climbing up the interradial 

 or the strong and convenient base-line (B JB), she runs to a point (2) 

 near the apex, crosses the two intermediate radii, and passes along 

 the upper radius to the attachment of the first interradial (*S"). On 

 reaching this, she turns and moves for about her own length tow- 

 ard the apex. Contrary to the usual habit of spiders, during this 

 roundabout passage from 1 to 4 she spins no thread. She now spreads 

 her spinners a little, and presses them upon the radius, keeping them 

 so while she advances again about her own length. This forms the 

 attachment of the second interradial. The spider then lets her abdo- 

 men fall somewhat, supporting her body and advancing upon the line 

 by means of her first, second, and third pairs of legs. The fourth pair 

 are applied together to the spinners with great rapidity, at least five 

 times in a second or three hundred times in a minute, and in so doing 

 they draw out a double litie. 2 



The spider moves slowly along the radius until she reaches a point 

 (5) where she can step across to the next radius (H"). While so doing, 

 she ceases to draw out the double line, and carefully keeps it from 



1 From a notice in the American Naturalist for February, 1875 (page 125), it appears 

 that Mr. A. J. M. Underbill has lately published, in Science Gossip, some observations 

 upon the employment of the different pairs of spinners. He assigns to the third (mid- 

 dle ?) pair the production of a line which is either viscid or curled. 



2 I must here admit an error in a previously-published account of the net (" Proceedings 

 of the American Association for the Advancement of Science," 1873, pages 264-274). 

 The interradial lines were there described as viscid. The fact is, that I had never thought 

 it necessary to examine them under the microscope, since the interradial lines of all the 

 Epeiridm are viscid ; that is, consist of a slender axis enveloped by a viscid coating, 

 which, soon after the net is completed, runs spontaneously into minute globules. Find- 

 ing that the interradial lines of the "triangle-spider" were elastic, and that they readily 

 adhered to the prey, or to any other body, I not unnaturally, but most unscientifically, 

 drew the inference that with this spider the lines were likewise viscid. During the sum- 

 mer of 1874, while examining the manner of attachment of these lines to the radii, I saw 

 that the interradial lines were neither viscid, like those of the Epeiridm, nor provided 



