n8 



THE COMMON SPIDERS 



Theridium unimaculatum. — This little species differs in color 

 and markings from all the others, and may almost alwavs be 

 distinguished by the white abdomen, with a black spot in the 



Fig. 276. Web of Steatoda borealis on the face of a conglomerate rock in the cavity 

 from which a pebble has dropped out. Half the real size. 



center of the back. The females are a twelfth of an inch long 

 and the males smaller. The cephalothorax is orange yellow, 

 with a black spot around the eyes, extending back in a point 

 as far as the dorsal groove, and there is also a fine black line 



