INSECTS AND THEIR NEAR RELATIVES, 



39 



the habits of this spider (see Popular Science Monthly^ 1875), 

 illustrates the form of the web. It consists of four plain 

 lines corresponding to the radiating Hnes of an orb web, and 

 a series of double cross lines, which are spun by the cribel- 

 lum and calamistrum. From the point where the radiating 

 lines meet a strong line extends to one of the supporting 

 twigs. Near this twig the spider rests, pulling the web tight 



Fig. 45. — Web of Hyptiotes cavaius. (From Wilder.) 



SO that there is some loose line between its legs, as shown in 

 the enlarged figure. When an insect becomes entangled in 

 one of the cross lines, the spider suddenly lets go the loose 

 line so that the whole web springs forward, and the insect is 

 entangled in other cross threads. The spider then draws 

 the web tight and snaps it again. This may be repeated 

 several times before the spider goes out upon the web after 

 its prey. 



Uloborus (U-lob'o-rus). — The spiders of this genus make 

 round webs which resemble at first sight those of the Orb 

 Weavers ; but they differ from the ordinary orb webs in that 



