298 



THE DESCENT OP MAN. 



■whether their great size can thus be accounted for. We have seen 

 that they are used by the Lucanus elaphus of N. America for seiz- 

 ing the female. As they are so conspic- 

 uous and so elegantly branched, and as 

 owing to their great length they are not 

 well adapted for pinching, the suspicion 

 has crossed my mind that they may in 

 addition serve as an ornament, like the 

 horns on the head and thorax of the 

 various species above described. The 

 male Chiasognathus Grantii of S. Chile 

 — a splendid beetle belonging to the 

 same family — has enormously developed 

 mandibles (fig. 24) ; he is bold and pugna- 

 cious; when threatened he faces round, 

 opens his great jaws, and at the same 

 time stridulates loudly. But the mandi- 

 bles were not strong enough to pinch my 

 finger so as to cause actual pain. 



Sexual selection, which implies the pos- 

 session of considerable perceptive powers 

 and of strong passions, seems to have 

 been more effective Vi^ith the Lamellicorna 

 than with any other family of beetles. 

 With bome species the males are provided 

 „ . with weapons for fighting; some live in 



^ S. $ \ pairs and show mutual affection; many 



have the power of stridulating when ex- 

 cited; many are furnished with the most 

 extraordinary horns, apparently for the 

 sake of ornament; and some, which are 

 diurnal in their habits, are gorgeously 

 colored. Lastly, several of the largest 

 beetles in the world belong to this fam- 

 ily, which was placed by Linnaeus and 

 Fabricius at the head of the Order.'= 



* . -, - Strldulati7ig organs. — Beetles belonging 



' ? to many and widely distinct families pos- 



Pig. 24. Chiasognathus sess these organs. The sound thus pro- 



grantii, reduced. Up- duced can Sometimes, be heard at the dis- 



per flgrure, male; low- ta,nce of several feet or even yards," 



er figure, female. ^^^ jj. j^ ^^^ comparable with that 



made by the Orthoptera. The rasp generally consists of 



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

 '"■ 'VVollaston, 'On certain Musical Curculionidae,' 

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



'Annals and Mag. 



