Superfamily Argiopoidea 



armed with teeth, on that part of the abdomen that overhangs 

 the thorax, and of a plate marked with numerous, fine, trans- 

 verse striae on each side of that part of the thorax overlapped 

 by the abdomen. The abdomen is freely movable up and down; 

 and by rubbing the teeth on the abdomen across the striae on the 

 thorax a feeble sound is produced. 



While several species live in houses and other protected 

 places, a larger number live on plants in the fields. Most species 

 build irregular webs of the type built by the house-spider men- 

 tioned above; but some {Argyrodes) live 

 as commensals in the webs of other 

 spiders; and a few (Euryopis) do not live 

 in webs and spin very 

 little, but are found 

 under stones, or in moss ^^^y-i 

 and leaves, and run with ^r ijy £r^ V 

 great rapidity. 



b _ r r , • Fig. 325. STRIDULATING ORGANS OF ASAGENA 



One genus of this 

 family, Latrodedus, is of especial interest as to it belong those 

 spiders which in all countries where they occur are greatly 

 feared on account of the supposed deadly nature of their bite; 

 a single species of this genus occurs in the Southern States. 



Most of the silk spun by the comb-footed spiders is of the 

 plain type; but occasionally a viscid thread is used. A speci- 

 men of Steatoda borealis which 1 had in a cage spun threads upon 

 which the viscid drops could be seen with a hand lens. It has 

 been shown by Apstein ('89) that the Theridiidae agree with the 

 Argiopidae in the possession of the aggregate silk glands which 

 are supposed to be the source of the viscid silk. 



But the most characteristic silk of the theridiids is that used 

 for enveloping their prey; this is thrown over their victims by 

 the comb on the hind tarsi, and is supposed to be derived from 

 the lobed silk glands, which have been found only in this family. 

 These glands open through a spigot without a tip on the hind 

 spinnerets (Apstein '89). 



TABLE OF GENERA OF THE THERIDIID/E 



A. Lateral eyes of each side widely separate. 



B. Abdomen flattened, and broad behind. P. 142. Episinus 



333 



