16 F. P. SMITH ON THE SPIDERS OF THE SUB-FAMILY ERIGONINAE. 



approaching buzz, to remain motionless until the supposed 

 victim absolutely touched the snare, Some species of Aranea 

 which are much persecuted by fossorial wasps have been seen 

 to drop suddenly from their snares upon the approach of their 

 tormentors; and, by mechanically imitating the buzzing of one 

 of these insects, I have been able to produce, although by no 

 means invariably, a similar result. 



The falces of the Linyphiidae are devoid of any basal pro- 

 tuberance, a very constant structure in some of the spider families ; 

 but their outer surface is furnished with a number of more or 

 less parallel ridges, which are actuated by a point upon the 

 palpus, no doubt for the purpose of stridulation. In some 

 species these ridges are almost obsolete and broken up into a 

 number of short pieces ; but in most cases they are quite distinct 

 under careful illumination and accurate focussing. In some 

 species — for example, those of the Walckenaera group — the ridges 

 are widely separated and few in number, whereas in the genus 

 Erigone they are excessively fine and close together. The clypeus 

 — i.e. the space between the anterior row of eyes and the front 

 edge of the caput — is hardly ever narrower than the distance 

 between lines tangential to the fore edges of the anterior central 

 eyes and the hinder edges of the posterior centrals. 



The family Linyphiidae, as defined by the foregoing characters, 

 may be synomymically expressed as follows : 

 Linyphiidae (ad partem), Black wall, 1861. 

 Theridiides (ad partem), 0. P. Cambridge, 1878-81. 

 Argiopidae (ad partem), E. Simon, 1895, etc. 

 To be more concise, Blackwall's Linyphiidae consists of those 

 species which are common to both Mr. Cambridge's Theridiides 

 and Mr. Simon's Argiopidae, whilst my Linyphiidae is equivalent 

 to Blackwall's, less the genus Pachygnatha. 



The numerous species constituting the family Linyphiidae fall 

 into two divisions, whose systematic separation, however, owing 

 to the presence of many intermediate forms, is a matter of great 

 difficulty. Having before us a vast and heterogeneous assemblage 

 of creatures which have apparently developed along two divergent 

 main lines from a common stock, it is, of course, only natural 



