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 

 more or less atrophied, with the tibiae and 

 deres distortus tarsi reduced to mere rudimentary knobs. 



(much enlarged). J 



Tipper figure, The winsrs, also, in the two sexes often differ 



male; lower fig- to ' ' 



ure, female. m neuration, 10 and sometimes considerably 



about Penthe, 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. 



Fig. 9. — Taphro- 



