54 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Parts of 

 the Orb. 



1. In Full Orb snares the spiral concen- 

 trics cross all the radii, appearing to form 

 conii)lete circles. (See Fig. 47.) They are 

 divided into Simple and Compound snares. 



a. A Simple orbweb is simply an orb of 

 radiating straight lines crossed by si)iral or 

 looped lines. The snare of the Furrow spi- 

 der (Epeira strix) is a typical example. 



b. A Comi>ound orbweb adds to the sim- 

 ple orb a system of netted or retitelarian lines 

 crossed and joined at different angles, and 

 placed above and on either side of the upper 



Fig. 49. Subdivisions of an orbweb. part of the oi'b, or placcd bclow tlic orb. The 

 snare of the Labyrinth Spider (Epeira labyrinthea) is an example. Sim- 

 ple orbicular snares may be approximately arranged into three groups 

 according as they have the Hub Meshed, Sheeted, or Open. 



I am not aware that any arrangement, description, or nomenclature of 

 the various parts of the orbweb has ever been attempted apart from the 

 following, which will therefore be found convenient and perhaps 

 sufficiently comprehensive.^ The orb may be naturally divided 

 into the Central Space, CS, the Spiral Space, SS, and the Foun- 

 dation Space, FS. (See Fig. 49.) 



The Central Space is included between the centre of the orb and the 

 origin of the Spiral Space. It has three 

 distinct parts, the Hub, the Notched zone, 

 and the Free zone. The Hub is a small 

 circular part immediately surrounding the 

 centre, which is either wholly open, or 

 covered in whole or in part by spinning- 

 work. 



1. The Meshed IIul) is wholly or partly 

 covered by a series of irregularly shai^ed 

 meshes, througli which one can often trace 

 the continuation of the radii as zigzag lines. 

 In fact, it may ))e considered as a small 

 rudimentary and irregular orbweb (Fig. 

 50). Usually it nearly corresponds in size 

 to iIk' length (including the legs) of the 

 spider that has woven it. 



The spider wlicii waiting for her prey 

 upon licr snare is frequently and at night 

 generally stretched upon or near this hul), fig.so. Meshed nub ami central space. 



1 First |.iilili.<lic,| ill "Our ( 'ontinciit," l'liila(U'li>hia, No. 33, page 362, 1882, and "Pro- 

 c-eedin-,'?^ of tlic, Ac;uK'iiiy ..f .\atural Sciences," Pliila'lclphia, 1882, page 257. 



