THE SPIDER 



109 



spider. If an insect should enter the web, the spider releases 

 its pull upon the central part, and the web springs out- 

 ward, strikes the insect, and causes it to adhere to the 

 threads. 



While, on the one hand, some spiders have evolved in the 

 direction of the construction of complicated webs, some, on 

 the other band, have never ac- 

 quired the web-spinning habit. 

 Such, for example, are the wander- 

 ing spiders, which may be classi- 

 fied into three chief groups. 



(1) Crab spiders are so called 

 because they run sideways. They 

 make nests by fastening together 

 leaves by threads of silk. Their 

 young are reared in these nests, 

 and watched over by the mother 

 (Fig. 11.3). 



(2) Running Spiders. — These 

 are for the most part large and 

 powerful species which wander 

 over fields or along watercourses in search of prey. Our North- 

 ern species are chiefly "wolf spiders" (Lycosidse,^ Fig. 114). 

 The female carries her eggs about in a special cocoon attached to 

 the end of the abdomen. The young are borne on the back 

 of the mother. The great size, black color, and hairiness of 

 some of these spiders have given them an apparently unjusti- 

 fied reputation of being very poisonous. Naturalists who have 

 allowed these spiders to bite the hand report that the bite is 

 rarely more poisonous than that of the mosquito. Some of 



' lykos, wolf. 



Fic. 110. — Diagram on nomencla- 

 ture of parts of an orb-web. FS, 

 foundation space ; SS, spiral 

 space ; CS, central space ; FZ, 

 free zone ; IVZ, notched zone ; H, 

 centre. From McCook. 



