Chap. X.] 



COLEOPTERA. 



369 



a Trox sahulosus, a gamekeeper who stood by thought that 

 he had caught a mouse ; but I failed to discover the proper 

 organs in this beetle. In Geotrupes and Typhseus a nar- 

 now ridge runs obliquely across (r, fig. 25) the coxa of 

 each hind-leg, having in G. stercorarlus eighty-four ribs, 

 which are scraped by a specially projecting 

 part of one of the abdominal segments. In 

 the nearly-allied Cop7'is lunaris, an exces- 

 sively narrow fine rasp runs along the sutu- 

 ral margin of the elytra, with another short 

 rasp near the basal outer margin ; but in 

 some other Coprini the rasp is seated, ac- 

 cording to Leconte," on the dorsal surface of 

 the abdomen. In Oryctes it is seated on 

 the pro-pygidium, and in some other Dy- 

 nastini, according to the same entomolo- 

 gist, on the under surface of the elytra. ^^ 

 Lastly, Westring states that in Omaloplia Fig. 25.— Hind-leg 



, , -IT .1 of Geotrupes ster- 



brunnea the rasp is placed on the pro- corarUis (from 

 sternum, and the scraper on the meta- 



, , r. Rasp. c. Coxa. 



sternum, the parts thus occupymg the /. Femur. <. Tibia. 

 under surface of the body, instead of the 

 upper surface as in the Longicorns. 



We thus see that the stridulating organs in the difier- 

 ent coleopterous families are wonderfully diversified in 

 position, but not much in structure. Within the same 

 family some species are provided with these organs, and 

 some are quite destitute of them. This diversity is intelli- 

 gible, if we suppose that originally various species made 

 a shuffling or hissing noise by the rubbing together of the 

 hard and rough parts of their bodies Avhich were in con- 

 tact ; and that, from the noise thus produced being in 

 some way useful, the rough surfaces were gradually de- 



■" I am indebted to Mr. Walsh, of Illinois, for having sent me extracts 

 from Leconte's 'Introduction to Entomology,' pp. 101, 143. 



