Stridulating- Organs in the Genus Scytodes. 373 
fro, pass over the ridges on the mandible, and perhaps produce 
a strident sound of greater or less intensity (see figures I. 
and II.). 
Of several other genera, Lowxosceles and Dietis, for instance, 
which M. Simon regards as closely allied to Scytodes and 
Thomisoides, it is noteworthy that they show no signs of 
either ridges on the mandibles or spines on the palpus. At 
any rate, the species which 1 have been able to examine— 
Lowxosceles rufescens, L. Duf., and Dictis gilva, Thor.—do not. 
M. Simon, in ‘ Histoire Naturelle des Araignées,’ regards 
the generic term Dictis as a synonym of Scytodes., One 
would, however, be inclined to think that the absence of this 
organ might be a sufficient reason for keeping the genera 
Scytodes and Dictis quite distinct, as originally contemplated 
by Dr. Thorell. 
Of those other organs to which I have briefly referred 
above, consisting of a deep fovea in the base of the abdomen, 
just above the pedicle, working in correlation with the 
roughened or developed and prominent end of the cephalo- 
thorax, I may refer to those visible in certain genera of the 
family Theridiide, as, for instance, in Steatoda, Asagena, 
Pedanostethus, &c. 
But by far the most remarkable and the most highly 
specialized of these organs yet observed is that recently 
discovered by Mr. Pocock in the male of Cambridgea anti- 
podiana (White), and described, with figures, in the Ann. & 
Mag. Nat. Hist. ser. 6, vol. xvi., Sept. 1895, in a paper 
entitled “ On a new Sound-producing Organ in a Spider.” 
In this case the upper surface of the pedicle is produced in 
the form of a sharp, curved, triangular blade, which, when 
the abdomen is moved, works in and across a deeply corru- 
gated fovea in the base of the abdomen. 
