402 ARACHNIDA—ARANEALE CHAP. 
any clear line between certain groups which he 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 chelicerae 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 Epistyinar 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, 
