402 ARACHNIDA ARANEAE CHAP. 



any clear line between certain groups which lie previously 

 classed under the Theridiidae and the spiders commonly known 

 as Epeiridae, that he has recently removed them from the 

 Theridiidae and united them with the orb-weaving spiders to 

 form the Family Argiopidae, the family name Epeiridae being dis- 

 carded. The groups which, in his view, belong to the Argiopidae 

 will be indicated below. This view has not met with universal 

 acceptance, and notwithstanding the undoubted difficulty of 

 clearly distinguishing between the two families, it is more con- 

 venient in the present work to maintain as a separate family a 

 group of spiders nearly all of whose members possess the easily 

 recognised characteristic of spinning a circular snare. 



The Theridiidae and the Epeiridae form the great bulk of the 

 sedentary spiders. They do not wander in search of prey, but 

 sit in snares of various structure and wait for their victims to 

 entangle themselves. The spinnerets, organs whose peculiarities 

 are often strongly marked in other families, are here wonderfully 

 constant in their arrangement and general appearance, forming 

 a compact rosette-like group beneath the abdomen. Their eyes, 

 normally eight in number, present an infinite variety of arrange- 

 ment. Their clielicerae and mouth-parts vary considerably, but 

 no abruptness of variation is distinguishable. This is unsatis- 

 factory from a systematic point of view, and the necessary result 

 is that certain groups might with equal propriety be classed 

 with the Theridiidae or the Epeiridae. The latter family will 

 here be taken as including all the orb-weaving spiders and a few 

 groups which appear inseparable from them. 



We shall consider the Theridiidae as comprising the seven 

 sub-families, ARGYRODINAE, EPISININAE, THERIDIONINAE, PHORON- 

 CIDIINAE, ERIGONINAE, FORMICINAE, and LINYPHIINAE, and shall 

 briefly deal with them in this order. 



(i.) The ARGYRODINAE are very curious spiders with very long 

 and often flexible abdomen. They are commonly parasitic on 

 the circular snares of Epeirid spiders, between the rays of which 

 they spin their own irregular webs. There are three genera, 

 Argyrodes, Ariamnes, and Rhomphaea, which are distributed in 

 the tropical and sub-tropical regions all over the world. 



(ii.) The EPISININAE hardly conform to the character of 

 sedentary spiders, being frequently found outside their webs. In 

 most species the abdomen is narrow in front and broader behind, 



