585 

 POWER TO UTTER SOUNDS. 



At p. 97, in describing the abdomen of Steatoda bipunctata, and 

 also at (p. 1 1 -2), that of Asagena pJialerata,an apparatus isinentioned 

 as enabling the spider to emit sounds by means of the friction of 

 two serrated or roughened surfaces against each other. Other 

 spiders of the samo f genus are furnished with a somewhat 

 similar apparatus ; but I am not aware that sounds have been 

 heard in any instance excepting that of A. phalerata. The 

 apparatus in these cases is either confined to the male, or 

 is imperfectly developed in the spider. A stridulating 

 apparatus has also been found in a large Indian spider of the 

 family Tlicraphosides — My gale stridulans, Wood-Mason. A loud 

 squeaking sound is emitted by this spider by means of a scraper 

 of sharp spines on the falces, acting upon a kind of comb formed 

 by elastic corneous rods, situated on the inner face of themaxillas. 

 My friend, Mr. F. M. Campbell, of Hoddesdon, has discovered a 

 roughened surface on the outer sides of the falces of some small 

 British spiders of the genus Zinypkia, formed either by trans- 

 verse grooves, or raised bands, which he believes to be intended 

 to act as a stridulating apparatus, by means of the friction of a 

 horny knob on the inner surface of the third joint of the palpus. 

 This structure is found in both sexes, but no sound has yet 

 been heard from it. I have myself observed somewhat similar 

 transverse bands on the outer side of the falces of several other 

 small spiders ; and it is quite possible that the palpi may be used 

 to rub against them either with or without a special knob or 

 series of points on some one or othor of their joints. I look 

 upon this question, however, as very far from settled, though 

 an interesting point is indicated for the observation of facts 

 connected with it. Where stridulating noises are actually 

 made by spiders, it is probably for the purpose of attracting the 

 notice of the opposite sex. Mr. Campbell has lately read a 

 paper on this subject before the Linnoan Society, but beyond 



1 1 havo also lately noticed this apnaratus in Nbrient aUnpttnclata. Cambr. 

 (p. 122). 



