178 AMERICAN SPIDERS 



nificant as indicating intermediate stages. The basilica spider, Al- 

 lepeira, still entirely encloses its web within a maze of threads. The 

 labyrinth spiders, Metepeira, largely preserve the lower maze as a 

 tangle placed behind the orb, in which the spider rests. 



The spiders that inherited the tradition of the formal orb trap 

 comprise a multitudinous group, of which many are familiar because 

 of large size, bizarre form, and bright coloration. They are specially 

 noticeable during the fall months, when their orbs, and the spiders 

 themselves, attain maximum size and cover the vegetation in great 

 profusion. Many of the spinners are fat little creatures that hang 

 serenely in the hubs of their webs, head-downward, claws pulling 

 the rays taut, poised to move in the direction of any disturbance. 

 Others are less bold; they sit in the comparative security of a leafy 

 nest, but they are attentive to the thread that communicates with 

 the center of their snare. All are accomplished trapeze artists, and 

 swing across the lines with grace and precision. They have pro- 

 duced many different types of orb webs; but while their success 

 must be largely attributed to the perfection of this trap, they have 

 also sacrificed much to gain their pre-eminence among the space 

 web spinners. 



They resemble the linyphiids rather completely in fundamental 

 features. The cephalothorax is lower and wider in front; the eyes, 

 invariably small and little used, lie near the front edge. The cheli- 

 cerae are large and strong, and the maxillae are short and parallel, 

 never pointed inward. The legs may be long and well spined, but 

 they are frequently quite short and stout. They lack the stridulat- 

 ing organs present on the chelicerae of the linyphiids. Sexual di- 

 morphism is often very pronounced. In many instances, the males 

 are quite safe within the bounds of the female's web, but not infre- 

 quently she is an ogress. 



The developmental history of the orb web is only vaguely indi- 

 cated in the spinning of modern orb weavers, which retain the 

 essential details as an instinctive racial memory. The baby spider 

 weaves its remarkably symmetrical web soon after leaving the egg 

 sac, and thereafter, throughout its lifetime, modifies the plan only 

 in minor ways. The spinning of an orb web is an involved process 

 consisting of a series of separate steps. The spider must first delimit 

 the area of operations by framing it with silken lines. The first and 

 most important line is a more or less horizontal bridge on which the 

 whole web is hung. There are two way of establishing this bridge 

 line. A thread may be emitted from the spinnerets and floated in the 



