CnAP. X.] 



COLEOPTERA, 



369 



a Trox sabulosus, 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 Typhams a nar- 

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

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

 which are scraped by a specially projecting 

 part of one of the abdominal segments. In 

 the nearly-allied Gopris 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, 73 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. 8 



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



.. ° . _ of Geotrupes ster- 



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



Landois). 



r. Rasp, c. Coxa. 

 /. Femur, t. Tibia. 

 tr. Tarsi. 



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 the stridulating organs in the differ- 

 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 which were in con- 

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

 some way useful, the rough surfaces were gradually de- 



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

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



