Chap. X. 



Coleoptera. 



;oi 



enormously developed mandibles (fig. 24) ; he is bold and pug- 

 nacious ; when threatened he faces round, opens his great jaws, 

 and at the same time stridulates loudly. 

 But the mandibles were not strong 

 enough to pinch my finger so as to 

 cause actual pain. 



Sexual selection, which implies the 

 possession of considerable perceptive 

 powers and of strong passions, seems 

 to have been more effective with the 

 Lamellicorns than with any other 

 family of beetles. With some species 

 the males are provided with weapons 

 for fighting; some live in pairs and 

 show mutual affection ; many have 

 the power of stridulating when excited ; 

 many are furnished with the most ex- 

 traordinary horns, apparently for the 

 sake of ornament ; and some, which 

 are diurnal in their habits, are gor- 

 geously coloured. Lastly, several of 

 the largest beetles in the world belong 

 to this family, which was placed by 

 Linnaeus and Fabricius at the head of 

 the Order. 72 



Stridulating organs — Beetles belong- 

 ing to many and widely distinct 

 families possess these organs. The 

 sound thus produced can sometimes 

 be heard at the distance of several feet 

 or even yards, 73 but it is not comparable 

 with that made by the Orthoptera. 

 The rasp generally consists of a narrow, 

 slightly-raised surface, crossed by very 

 fine, parallel ribs, sometimes so fine as 

 to cause iridescent colours, and having 

 a very elegant appearance under the 

 microscope. In some cases, as with 

 Typhosus, minute, bristly or scale-like 

 prominences, with which the whole 

 surrounding surface is covered in approximately parallel 

 lines, could be traced passing into the ribs of the rasp. The 



Fijr. 24. Chiasognatbusgrantii, 

 reduced. Upper figure, male ; 

 lower figure, female. 



72 V/estwood, ' Modern Class.' 

 rol i. p. 184. 



73 Wcllaston, ' On certain Musical 



Curculionidse,' 'Annals and Mag. of 

 Nat. Hist.' vol. vi. 1860, p. 14. 



