SPIDERS. 253 



-species of Epeira place themselves in the centre of 

 their net, with their heads directed downwards. 



The Melon Spider l is not more than a quarter of 

 an inch in length, and its conspicuous oval abdomen 

 is of a melon-green colour, with a red spot at the outer 

 extremity. Its geometrical net is often horizontal, but 

 sometimes inclined, attached to shrubs, to which also 

 its cocoon, of bright yellow silk, is affixed. Another, 2 

 even more common, species constructs a geometrical 

 net in woods, with a vacant space in the centre, which 

 it usually occupies. Whenever disturbed, it drops 

 suddenly, as if falling to the ground, but really remains 

 suspended by a thread, along which it regains its 

 position in the centre of its snare when all danger is 

 past. Most of the species in this group have the 

 abdomen beautifully variegated with white and black 

 spots and lines. 



Mr. Blackwell has calculated the number of viscid 

 globules which would be distributed over a geometric 

 web of a medium size. He says that " The mean dis- 

 tance between two adjacent radii is about seven-tenths 

 of an inch : if, therefore, the number seven be multi- 

 plied by 20, the mean number of globules which 

 occur on one-tenth of an inch of the elastic spiral 

 line at the ordinary degree of tension, the product will 

 be 140, the mean number of globules deposited on 

 seven-tenths of an inch of the elastic spiral line. This 

 product multiplied by 24, the mean number of cir- 

 cumvolutions described by the elastic spiral line, gives 

 3,360, the mean number of globules contained between 



1 Epeira ciiciirbitina. a Epeira ittclinata. 



