150 ARTHROPODA. 



(c) Four pairs of walking legs. Count their segments and see 

 if they are armed with claws. 



(d) The comb-shaped pectines. Are they on the thorax or 

 the abdomen? Their function is doubtful. 



5. Examine the mouth. Are there any jaws? Is a labrum 

 present ? 



6. Find the position of the anus. The terminal spine is pro- 

 vided with a poison gland and serves as a sting. In the living 

 animal, the post-abdomen is habitually carried over the back. 



Make a drawing of the under side of a specimen. 



EPEIRA. (Round-Web Spider.) 



Examine the webs of different species of spiders and see how 

 they are constructed. Do all of the webs have places for the 

 concealment of the owners? Do all spiders seem to construct 

 definite webs for the capture of insects ? How do spiders entan- 

 gle insects in their webs? Do different kinds use different 

 methods? What parts of insects are eaten? 



By destroying webs that are occupied by spiders that are in 

 convenient places for observation, the construction of new webs 

 may be observed. Notice how the framework is laid and then 

 how the threads are attached to the framework. Are any of 

 the legs used in handling the thread ? Are spiders equally active 

 at all times of the day? 



Spiders' webs may frequently be seen floating in the air, 

 especially in the late summer or autumn. By watching spiders 

 that are on fences and bushes the formation of these threads 

 may be observed. Watch such a spider and see if you can deter- 

 mine the use to which the thread is put. 



Capture a spider and watch it descend by a thread. Where 

 is the thread formed? Does the spider hold to it with its legs? 

 Keep taking the thread up so that the spider cannot reach the 

 ground, and see if there is a limit to the amount that can be 

 formed. When the spider starts to climb the thread see how 

 this is done, and whether the thread is taken up as the animal 

 climbs or is allowed to float free. 



