THE FEATHERFOOT SPIDER, ULOBORUS PLUMIPES, 



177 



the centre; in the structure of the huVj; in the preliminary spiral scaffold; 



in the central concentrics, which correspond with the notched zone ; in 



the form and distrihution of the spirals; in the character of the 



• r^K riljbon decorations; in the manner in which the snare is swung 



_ „ to foundation lines in whatever site it may be i)laced; in the 



weaver. -^ '■ ' 



position of the spider underneath the web ; — in all these points 

 the spinningwork of Uloborus is analogous to that of Orbweavers, espe- 

 cially Tetragnatha, or of the Orchard and Hunchback spiders. 



There is, however, one important difference. The spiral concentrics, in- 

 stead of being composed of single lines covered with viscid beads, as in 

 tyi)ical snares of the Orbitelariee, are composed for the most part 

 of several very delicate filaments, although in certain parts the 

 thread is single. To threads and filaments alike are often at- 

 tached a number of minute objects, opaque, and for the most part amor- 

 phous; but many of them being very small globes of a yellow color, per- 



No Viscid 

 Beads. 



Fig. 164. Circular ribboned decorations on the snare of Uloborus. 



haps the pollen of flowers. They adhere to the single threads, but more 



fully to the portions containing several distinct filaments. These opaque 



objects have so much the a|)pearance of beads that a careless observer is 



likely to be deceived by them ; at least, I was thus led astray in my first 



studies of the Uloborus snare. There are, however, no viscid beads upon 



any of the lines, although the thread is certainly very adhesive, chiefly 



I suppose by reason of the delicacy and flocculence of the fibre. The 



smooth point of a pencil touched to it does not adhere ; but when my 



finger was laid upon a spiral it adhered as in the case of a beaded web. 



In this respect the snare of Uloborus resembles that of the Triangle 



spider, Hyptiotes cavatus, and also certain species of the Clubion- 



Kelations j,!,^,^ such as Dictyna philoteicluis and other species of that genus. 



, . This flocculent web was discovered and described by Blackwall, 

 culent 1-1 J ' 



Spirals. '^'"' ^^ produced by special organs known as the cribellum and 



calamistrum. The calamistrum is located upon the metatarsus 



of the hind i>airs of legs. It resembles somewhat in form the flyers upon 



