The Structure and Habits of Spiders. 75 



threads being parallel, and crossed by shorter 

 ones at regular intervals, Fig. 37. Others are 

 circular, with a tube in the centre which runs 

 into a crack, and from which radiate irregularly 

 the principal threads of the web. Such webs 



Fig- 37- 



are sometimes very numerous on stone build- 

 ings, and, as they collect large quantities of 

 dust, seriously disfigure them. The webs alone, 

 when clean, would not be noticed. 



THE TRIANGLE SPIDER. 



Among those spiders that use the calamis- 

 trum is one which makes a web unlike any 

 other. It has been described by Professor 

 Wilder, in the " Popular Science Monthly " for 

 April, 1875, under the name of the "triangle 

 spider." It lives usually among the dead 

 branches around the lower part of pine and 

 spruce trees, and is colored so like the bark, 

 that when it stands, as it usually does, on the 



