THE CRIBELLATE SPIDERS 151 



metrical especially during the cocooning season, when the feeding 

 instinct is replaced by a maternal one and irregular in its details, 

 but it remains quite as pleasing to the eye as the snares of the typical 

 orb weavers. 



Special features of the web are the hub, which is closely and 

 beautifully meshed, and the ribboned decorations or stabilmenta 

 that ornament the orb and possibly add to its strength. The most 

 frequent form of the stabilmentum is a scalloped band that crosses 

 the central portion of the orb; it is scarcely visible at the delicate 

 hub. Other variations are numerous, a common one being a ribbon 

 coming from a nearby sector to form a V-shaped figure; or four 

 ribbons forming a cross; or broken or completed circles around 

 the hub. 



In position, the featherfoot spider lies stretched out beneath 

 the hub of her web, her legs directed forward and backward to 

 form a bridge between the stabilmenta and make a complete band 

 across the snare. As she hangs there, swaying with the breeze, she 

 often resembles a bit of leaf or stick. When her eggs are laid, she 

 places the several elongate sacs in a row across the web, and then 

 aligns her long body so that she becomes almost indistinguishable 

 from them one in a line of bits of debris. 



Among the tropical uloborids, it is interesting to note, are many 

 social spiders that spin immense webs, where large numbers of males 

 and females live amicably together. These colonial webs are fea- 

 tured by a large central retreat suspended from many long silk lines 

 running in all directions and forming a loose maze. Most of the 

 males, as well as many females and spiderlings, live in the inner part 

 of the web; but from time to time and this is a particularly fas- 

 cinating part of their activity individuals detach themselves and 

 move to open spaces on the periphery, there to spin their own 

 characteristic round webs. The outer part of the communal web 

 provides snare-space for all the spiders, and part of the time they 

 live singly in their tiny orbs. Mating takes place in the central re- 

 treat, and the egg laying occurs there as well. 



Several social species are found in the United States, but their 

 communal webs are rarely notable for size. Uloborus arizonicus, 

 occurring in the Santa Rita and other mountain ranges of south- 

 ern Arizona, will completely invest a low shrub with its web, and 

 several dozen individuals will live there together. Except for size, 

 the colonies of this species closely resemble those of the tropical 

 uloborids. 



