74 CENTIPEDES— SPIDERS. 



I may refer to Landois's interesting work, "TLier- 

 stimmen." 



From the fact that the power of producing sounds 

 audible to us is scattered among so many groups, and 

 that the sounds themselves are often so shrill, I am 

 disposed to suspect that many insects usually regarded 

 as dumb really produce sounds, which, however, are 

 beyond our range of hearing. 



Among centipedes Gertitiicker has described* a 

 sound-producing organ in Eucoryhar crotylus. The 

 posterior legs have the fourth segment much enlarged 

 and leaf-like, with the edges raised and formed of 

 very hard chitine. The legs are rubbed against one 

 another, and thus produce a rasping sound. Bourne 

 also has recently described! a stridulating organ in 

 another genus (Sphcerotherium). It is situated just 

 behind the twenty-tirst pair of legs, and consists of a 

 hood-like process bearing a number of parallel ridges. 



There is a very general impression that spiders hear 

 well, and even enjoy music! There seems, however, 

 very little evidence of any value on the subject. No 

 doubt they are extremely sensitive to vibrations. The 

 presence of even a veiy small insect on their web is 

 at once perceived. Mr. Boys has shown that the 

 vibrations of a tuning-fork affect them strongly.^ 

 This sensitiveness to vibrations is, however, not nece.s- 

 sarily the same as a true sense of hearing. Kraepelin 

 says § that he knows only one observation which seems 

 to him to possess suflicieut exactness to justify the 

 couclnsion that spiders possess any sense of hearing — 

 namely, that of Lchmann. 



* Gertitaukcr, " SMlln Ent. Zeit, 1854. 



t Uouriie, Lfuiu'un Juuntal, 18u>5. J Nature, vol. xsiii. 



(j " Ueber die Geruflisorgane der Gliedcitliicre." 



