SCHEFFKR : COCOONING HABITS OP SPIDERS. 101 



may have, in addition, foreign material added for protection. 

 When tube-shaped it is spun in crevices of wood or bark, in 

 stone fences, or in rolled leaves. When larger and more globu- 

 lar it is usually enclosed in a tent of leaves drawn together. 

 In one subfamily, at least (Sparassinse) , the female shuts her- 

 self up in the dwelling-sack, with the eggs. In other groups 

 the sack has one or two openings, allowing the mother spider 

 to perform sentinel duty and at the same time to pounce upon 

 stray insects for food. The female in some species is said to 

 defend her nest to the last ; in others to leave it at the approach 

 of danger. 



In contrast to the above practices, some members of this 

 family merely spin upon rocks or wood a plano-convex cocoon at- 

 tached by the flat face and having no outer protecting tent. The 

 cocoon itself, in this case, is of strong, paper-like tissue. It is 

 probable that a great many of the dry, parchment cocoons we 

 find on the sides of rocks belong to the genus Agroeca. Females 

 of the supergenus Ctenese are said to guard the otherwise un- 

 protected cocoon. 



A third method of procedure is that adopted by the Heter- 

 opodese. All members of this group that have been observed 

 carry their cocoon about with them, holding it close to the 

 sternum by means of the chelicerse and pedipalps. The cocoon 

 is disk-shaped and of rather firm tissue. 



Type: Trachelas tranctuilla. 



Females of this species can be found under bark or in wood- 

 piles. In such situations they spin their cocoons in September 

 and October. The cocoon consists of a low, dome-shaped cap, 

 resting upon a flat disk, which projects beyond the edges of 

 the convex piece so as to form a narrow border. This disk is 

 firmly glued to the surface of the wood or bark. Including the 

 disk, the cocoon is about three-eighths inch in diameter. When 

 first spun it is pure white, glossy, and of paper-like texture. 

 These qualities are not long apparent, however, for the mother 

 covers the entire surface with chewed bits of bark and then 

 spins a light web over the whole. The eggs, thirty or forty in 

 number, are creamy white and slightly agglutinate. 



