Chap. X. 



Coleoptera. 



303 



are completely reversed in position, for the rasps are seated on 

 the inferior surface of the elytra, near their apices, or along 

 their outer margins, and the edges of the abdominal segments 

 serve as the scrapers. In Pelobius Hermanni (one of Dytiscidae 

 or water-beetles) a strong ridge runs parallel and near to the 

 sutural margin of the elytra, and is crossed by ribs, coarse in 

 the middle part, but becoming gradually finer at both ends, 

 especially at the upper end; when this insect is held under 

 water or in the air, a stridulating noise is produced by the 

 extreme horny margin of the abdomen being scraped against 

 the rasps. In a great number of long-home i beetles (Longi- 

 cornia) the organs are situated quite otherwise, the rasp being 

 on the meso-thorax, which is rubbed against the pro-thorax; 

 Landois counted 233 very fine ribs on the rasp of Cerambyx 

 heros. 



Many Lamellicoms have the power of stridulating, and the 

 organs differ greatly in position. Some species stridulate very 

 loudly, so that when Mr. F. Smith caught a Trox sabuhms, a 

 gamekeeper, who stood by, thought he had caught a mouse ; 

 but I failed to discover the proper organs in ,. 



this beetle. In Geotrupes and Typhosus a / 



narrow ridge runs obliquely across (r, fig. 26) 

 the coxa of each hind-leg (having in G. ster- 

 corarius 84 ribs), which is scraped by a 

 specially projecting part of one of the ab- 

 dominal segments. In the nearly allied Coprfs 

 lunar is, an excessively narrow fine rasp runs 

 along the sutural margin of the elytra, with 

 another short rasp near the basal outer mar- 

 gin; but in some other Coprini the rasp is 

 seated, according to Leconte, 78 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. 



™^m—c 



Ficr. 26. Hind-leg of 

 Gfotrupos stercora- 

 ri us (from Landois). 



r. Rasp. c. Coxa. /. 

 Femur, t. Tibia 

 tr. Tarsi. 



We thus see that in the different coleopterous families the 



not, as far as I could judge, come 

 into play in scraping the rasps on 

 the elytra. 



78 1 am indebted to Mr. Walsh, 



of Illinois, for having sent me ex- 

 tracts from Leconte's ' Introduction 

 to Entomology,' pp. 101, 143. 



