MATERNAL INDUSTRY: COCOONS OF ORBWEAVERS. 



99 



yellow, glossy silk, and so abundant as to make quite a ribbon. Here the 



threads are carried around l)otli sides of a projecting twig, as though the 



spider motlier had purposely availed herself of this mechanical advantage, 



and are additionally strengthened by being crossed or twisted as they pass 



around the branch to which the cocoon 



is attached. The outer envelope is in 



color a very dark yellowish brown, and 



is of extraordinary stiffness. When cut 



open the bowl is found to contain a 



ball of white silken floss, within which 



the eggs are deiiosited. Tliis ball is 



n . T . , 1 i • . n 1 ^"'- 82- Fic. 83. 



raStenea to a very tOUgll twisted cord, Fic 82. CocoonofCyrtarachnecornigera (natural 



that ])asses Ul) thrOUgll the neck (Fig size), in site upon a twig. F.c.83. interior 



^ ^ " ^ *^ view of same. 



83), and which is the line by which the 



egg ball was suspended before the outer flask was spun around it. The 

 texture of the external .shell has every appearance, uniler the lens, of 

 having been hardened by means of a viscid secretion applied to it by the 

 spider ; the toughness is evidently not the result of simple weaving. 



Another example of Cornigera's cocoon is drawn at Fig. 84. The 

 manner in wliich the bowl of the vase shaped object is seated upon the 

 twig and lashed by a ribbon is there well sliown. The top of the stalk 

 is stayed by various lines wrapped al)0ut a neighboring twig. 



Epeira labyrinthea belongs to tlie small group of Orbweavers that spin 



compound snares ; that is, .snares in whicli the orb is associated with a 



well developed retitelarian snare. ^ Tlie labyrinth of crossed lines 



Laby- jg pi^t'od behind and above the orb, and within this the spider 

 ril'itii 



Snider ^^"'^ ^^'^^' '^^^''^lling, commonly beneath a dry leaf ; here also she 

 susi)ends her string of cocoons, placing them near her tent, and 

 usually above it ami to one side, as represented in Fig. 85. 



It consists of several, usually 

 Ave, lenticulai; or semiglobular 

 vessels, of a yellowisli, tough 

 texture, about one-fourth inch 

 lung and one-sixth wide. These 

 may be properly described as 

 woven di.shes with covers. Each 

 cocoon consists of two disks 

 joined together at the edges 

 tightly enough to cause them to 

 adhere until the parts are grad- 

 ually loosened before the strain of the growing spiderlings, and finally 

 open u[) and permit the inmates to escape. 



Fig. 84. Cocoon of Cyrtarachne cornigera, with ribbon 

 lasbing and stay lines. 



1 See Vol. I., page 131, and Fig. 115. 



