SEXUAL SBLECTIOir 897 



narrow fine rasp runs along the sutural margin of the elytra, 

 with another sharp rasp near the basal outer margin; but 

 in some other Coprini the rasp is seated, accprding to 

 Leconte," on the dorsal surface of the abdomen. In Oryctes 

 it is seated on the pro-pygidium; and, according to the same 

 entomologist, in some other Dynastini, on the under surface 

 of the elytra. Lastly, Westring states that in Omaloplia 

 brunnea the rasp is placed on the pro-sternum, and the 

 scraper on the meta-sternum, the parts thus occupying 

 the under surface of the body, instead of the 

 upper surface, as in the Longicorns. 



"We thus see that in the different coleopter- 

 ous families the stridulating organs are won- 

 derfully diversified in position, but not much 

 in structure. Within the same family some 

 species are provided with these organs, and 

 others are destitute of them. This diversity is 

 intelligible, if we suppose that originally vari- 

 ous beetles made a shuffling or hissing noise by 

 the rubbing together of any hard and rough 

 parts of their bodies which happened to be in j^^ 26 -Hind- 

 contact; and that, from the noise thus pro- stlroOTari^s*(ft-?S 

 duced being in some way useful, the rough c c'raa^/'r^^" 

 surfaces were gradually developed into regular *• ''''''*• **■• '^'^™- 

 Btridulating organs. Some beetles, as they move, now pro-- 

 duce, either intentionally or unintentionally, a shuffling 

 noise, without possessing any proper organs for the purpose. 

 Mr. Wallace informs me that the Ettchirus longimanus (a 

 Lamellicom, with the anterior legs wonderfully elongated 

 in the male) "makes, while moving, a low hissing sound 

 by the protrusion and contraction of the abdomen; and 

 when seized it produces a grating sound by rubbing its 

 hind-legs against the edges of the elytra." The hissing 

 sound is clearly due to a narrow rasp running along the 

 sutural margin of each elytron; and I could likewise make 



w I am indebted to Mr. Walsh, of Illinois, for having sent me extracts from 

 leconte's "Introduction to Entomology," pp. 101, 143. 



