ARTHROPODA. 235 



the different type of web. How is the web produced? 

 Details of the construction, and the order in which the 

 parts are made (Fig. 100). 



Select some well-developed web and watch the behavior 

 of the spider in reference to it. What is the usual position 

 of the spider? How does he behave when an insect be- 

 comes entangled in it? Study carefully; record all your 

 observations; indicate your conclusions as to the senses 

 on which the spider most depends in capturing his prey. 

 Do spiders develop directly or do they have a meta- 

 morphosis? Are "Daddy-long-legs" spiders or insects? 

 Mites and ticks belong to which division? Study figures 

 in text-books. 



253. " Thousand -legs :" a Practical Exercise. These 

 are elongated, weak-bodied creatures, which every student 

 has seen under boards and stones, or in other moist 

 places. The body may be flat, or rounded, in cross- 

 section. Each segment of the body may have one 

 (or two) pair of appendages. 



In how many different kinds of places have you found 

 them? Can you get any clue to their feeding habits? 

 What is their behavior on being exposed and touched? 

 How many segments in the body? How much variety 

 among the segments? How many pairs of appendages? 

 Are these all alike? Are they homologous? How many 

 different functions do you think these appendages may 

 perform? Evidences? 



Study the method of locomotion. In what way are 

 the numerous appendages used? Do all on one side act 

 at one time? If not, how do they act? 



What senses have the myriapods? Do these seem 

 more or less like annelids than the insects do? 



