154 ON THE STEIDULATING-OEGANS OF STEATODA, ETC. 



palps " and " the penultimate joint of the chelicerse." The organs 

 which I venture to call stridulating in both sexes of Linyphia tene- 

 bricola, Wider. ( = Linyphia terricola, ~Bla,ck\Y., = Linyphia tenuis, 

 Blackw.f), are also seated on the falces and palpi, but are of 

 different structure. I observed them while examining the palpal 

 organs with a f objective, and denned them with higher powers as 

 follows : — On the outer side of the basal joint of each falx are 

 about twenty parallel transverse chitinous bands, placed so that 

 their inferior edges are free (fig. 2, A), as is easily seen in section 

 (fig. 2, B). The effect, when viewed from the front, is that each 

 falx has a distinctly serrated outer edge, which becomes more de- 

 cided towards the base. The opposing surface is that of the 

 humeral joint of each palpus, which is marked with a more or less 

 regular series of curved grooves, deep enough to give the ap- 

 pearance of serration on its sides under a -§ objective. On the 

 inside of this joint close to its base is a curved enlargement, 

 and on the top a prominent, horny, somewhat triangular, knob- 

 like plate (fig. 2, C * and D *) with a rounded apex. This differs in 

 form, size, elevation, and position from the chitinous prominences 

 usually seen in connexion with spines, of w T hich there is one near 

 its side, but of which in some individuals it is independent. 



X7S 



Fig. 2. 



X3C0 



X30O 



Stridulating-organs of Linyphia tenebricola, Wider., $ . 



A. Right falx as viewed obliquely from the right side. 



B. Part of three stridulating-bands. The broken edge is to the reader's right. 



C. Humeral joint of left palpus, the spines being omitted, except those on 

 the inside. * Horny plate. 



D. Easal portion of third joint, showing at # the horny plate. 



These organs persist in all adult members of both sexes of this 

 species ; but those on the palpi of the females are not so highly 

 developed, the chief difference being the size of the enlarge- 



t See Thorell, 'Remarks on Synonyms of European Spiders,' p. 66; and 

 Cambridge, ' Spiders of Dorset.' 



