894 



THE DESCENT OF MAN 



and pugnacious; 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 efiEective 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 colored. Lastly, several of 

 the largest beetles in the world belong 

 to this family, which was placed by 

 Linnaeus and Pabricius at the head 

 of the Order." 



Stridulating Organs. — Beetles be- 

 longing to many and widely distinct 

 families possess these organs. The 

 sound thus produced can sometimes 

 be heard at the distance of several 

 feel;, or even yards," but it is not 

 Fia.Z4.-chisognathusgran- comparable with that made by the 



til (reduced). Upper figure, m 



male; lower figure, female. Orthoptera. The rasp generally con- 

 sists of a narrow, slightly raised surface, crossed by very 

 fine, parallel ribs, sometimes so fine as to cause iridescent 



« Westwood, "Modern Class.," vol. i. p. 184. 



■"s WoUaston, "On Certaia Musical Curoulionidae, " "Annals and Mag. of 

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



