57 



7. — Geometrical Webs. 



These familiar structures are the work of the family Epeiridm (Figs. 7 and 10). 

 The process of making them can be observed in any garden ; it is, of course, very different 

 from that described above in the construction of cobwebs. The net is usually fixed in a 

 perpendicular or somewhat oblique direction, in an opening between the leaves or branches 

 of some shrub or plant, in a window-frame or fence, or some such open wooden structure, 

 where there is a hole or crack in which they can hide when necessary. 



" It is obvious," to quote Kirby and Spence's description, "that round the whole extent 

 of the net, lines will be required to which can be attached those ends of the radii that are 

 furthest from the centre. Accordingly the construction of these exterior lines is the 

 spider's first operation. She is careless about the shape of the area which they enclose, 

 but is guided by the distance or proximity of the points to which she can attach them. 

 She spares no pains, however, to strengthen and keep them in a proper degree of tension. 

 With the former view she composes each line of five or six or even more threads glued, 

 together ; and with the latter she fixes to them from different points a numerous and 

 intricate apparatus of smaller threads. Having thus completed the foundations of her 

 snare, she proceeds to fill up the outline. Attaching a thread to one of the main lines, 

 she walks along it, guiding it with one of her hind feet that it may not touch in any part 

 and be prematurely glued, and crosses over to the opposite side, where, by applying her 

 spinners, she firmly fixes it. To the middle of this diagonal thread, which is to form the 

 centre of her net, she fixes a second, which in like manner she conveys and fastens to 

 another part of the lines encircling the area. Her work now proceeds rapidly. During 

 the preliminary operations she sometimes rests, as though her plan required meditation. 

 But no sooner are the marginal lines of her net firmly stretched, and two or three radii 

 spun from its centre, than she continues her labour so quickly and unremittingly that the 

 eye can scarcely follow her progress. The radii, to the number of about twenty, giving 

 the net the appearance of a wheel, are speedily finished. She then proceeds to the centre, 

 quickly turns herself round, and pulls each thread with her feet to ascertain its strength, 

 breaking any one that seems defective and replacing it by another. Next, she glues im- 

 mediately round the centre five or six small concentric circles, distant about half a line 

 from each other, and then four or five larger ones, each separated by a space of half an 

 inch or more. These last serve as a sort of temporary scaffolding to walk over, and to 

 keep the radii properly stretched while she glues to them the concentric circles that are 

 to remain, which she now proceeds to construct. Placing herself at the circumference, and 

 fastening her thread to the end of one of the radii, she walks up that one, towards the 

 centre, to such a distance as to draw the thread from her body of a sufficient length to 

 reach to the next ; then stepping across, and conducting the thread with one of her hind 

 feet, she glues it with her spinners to the point in the adjoining radius to which it is to be 

 fixed. This process she repeats until she has filled up nearly the whole space from the 

 circumference to the centre with concentric circles, distant, from each other about two 

 lines. She always, however leaves a vacant interval around the smallest first spun circles 

 that are nearest to the centre. Lastly, she runs to the centre and bites away the small 

 cotton-like tuft that united all the radii, which beinc? now held together by the circular 

 threads, have thus probably their elasticity increased ; and in the circular opening result- 

 ing from this procedure, she takes her station and watches for her prey." 



Some species, however, do not entirely surround the radii of their nets with 

 concentric circles, but leave one radius free, which serves as a sort of ladder for access to 

 the net. Others, again, spin spiral lines from the centre to the circumference, as shewn 

 in Fig. 24. In this case, when the radii are finished, the spider begins at the centre to 

 spin a spiral line across them, a, a, a, in Fig. 2i; the turns of the spiral being as far 

 apart as the spider can conveniently reach. She climbs from one radius to the next, 

 holding her thread carefully off with one of the hind-feet till she gets to the right point, 

 and then turns up her abdomen and touches the radius with her spinnerets, thus fasten- 

 ing the cross-threads to it. The figure shows her in this position. When this spiral 

 has been carried to the outside of the web, she begins there another and closer one 

 of thread of a different kind. While the first thread was smooth, the latter is 



