MATERNAL INDUSTRY : COCOONS OF ORBWEAVERS. 



99 



a twig " FlG ' 83 ' Interior 





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



threads are carried around both sides of a projecting twig, as though the 



spider mother 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 ^^ tlfev 



the eggs are deposited. This ball is pje g2 Fic , 83 



fastened tO a Very tOUgh twisted COrd, FIG. 82. Cocoon of Cyrtarachne cornigera (natural 



that passes up through the neck (Fig. 



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, under 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 which the bowl of the vase shaped object is seated upon the 

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

 is stayed by various lines wrapped about a neighboring twig. 



Epeira labyrinthea belongs to the small group of Orbweavers that spin 



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



well developed retitelarian snare. 1 The labyrinth of crossed lines 



Laby- j g pi ace( j behind and above the orb, and within this the spider 



^ n . , has her dwelling, commonly beneath a dry leaf ; here also she 



suspends her string of cocoons, placing them near her tent, and 



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



It consists of several, usually 

 five, lenticular or semiglobular 

 vessels, of a yellowish, tough 

 texture, about one-fourth inch 

 long and one-sixth wide. These 

 may be properly described as 

 woven dishes with covers. Each 

 cocoon consists of two disks 

 joined, together at the edges 



tightly enough to CaUS6 them to 

 fe * 



adhere until the parts are grad- 

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

 open up and permit the inmates to escape. 



FIG. 84. Cocoon of Cyrtarachne cornigera, with ribbon 

 lushing and stay lines. 



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



