334 



SEXUAL SELECTION, 



[Part II. 



"and obviously for the same end." In male dragon-flies, 

 " the appendages at the tip of the tail are modified in an 

 almost infinite variety of curious patterns 

 to enable them to embrace the neck of the 

 female-" Lastly, in the males of many in- 

 sects, the legs are furnished with peculiar 

 spines, knobs, or spurs ; or the whole leg is 

 bowed or thickened, but this is by no means 

 invariably a sexual character ; or one pair, 

 or all three pairs are elongated, sometimes 

 to an extravagant length. 8 



In all the orders, the sexes of many 

 species present differences, of which ' the 

 meaning is not understood. One curious 

 case is that of a beetle (fig. 9), the male of 

 which has the left mandible much enlarged ; 

 so that the mouth is greatly distorted. In 

 another Carabidous beetle, the Eurygna- 

 thus, 9 we have the unique case, as far as 

 known to Mr. Wollaston, of the head of the 

 female being much broader and larger, 

 though in a variable degree, than that of 

 the male. Any number of such cases could 

 be given. They abound in the Lepidoptera : 

 one of the most extraordinary is that cer- 

 tain male butterflies have their fore-legs 



Fig 9 _ Taphro- more or l ess atrophied, with the tibise and 

 deres distortus tarsi reduced to mere rudimentary knobs. 



(much enlarged). J 



Upper figure, The win^s, also, in the two sexes often differ 



male; lower fig- & > > 



ure, female. j n neuration, 10 and sometimes considerably 



about Pcnthe, and others in inverted commas, are taken from Mr. Walsh, 

 1 Practical Entomologist,' Philadelphia, vol. ii. p. 88. 



8 Kirby and Spence, ' Introduct.' etc., vol. iii. pp. 332-336. 



9 'Insecta Maderensia,' 1854, p. 20. 



10 E. Doubleday, « Annals and Mag. of Nat. Hist.' vol. i. 1848, p. 379. 



