ARTHRGPODA, 

 FIG. 149. 



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PIG. 149. Spiders (Epeira marmorea). After McCook. Male on left; female on right. 



Natural size. 



Questions on the figure. What differences do you note with re- 

 spect to the sexes? What habits of the spiders are correlated with this 

 difference in size in the sexes? 



FIG. 150. 



FIG. 150. Web of Epeira' strix, an Orb-weaving Spider. After McCook. 



Questions on the figure. By reference to other texts or by observa- 

 tion determine if there is any regular order in which the parts of the web 

 are produced. To what is this form of web an adaptation? Evidences? 

 What other forms of webs are constructed for similar purposes? 



