274 



THE DESCENT OP MAN. 



beetles) a few of the middle joints of the antennse are dilated and 

 furnished on the inferior surface with cushions of hair, exactly 



like those on the tarsi of the Car- 

 abidse, "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 en- 

 "able them to embrace the neck of 

 "the female." Lastly, in the males 

 of many insects, the legs are fur- 

 nished with peculiar spines, knobs 

 or spurs; or the whole leg is bowed 

 or thickened, but this is by no 

 means invariably a sexual charac- 

 ter; or one pair, or all three pairs 

 are elongated, sometimes to an ex- 

 travagant length.' 



The sexes of many species in all 

 the orders present differences, of 

 which the meaning is not under- 

 stood. One curious case is that of a 

 beetle (fig. 10), the male of which 

 has the left mandible much en- 

 larged; so that the mouth is greatly 

 distorted. In another Carabidous beetle, Burygnathus," we have 

 the case, unique as far as known to Mr. Wollaston, of the head of 

 the female being much broader and larger, though in a variable de- 

 gree, than that of the male. .4.ny number of such cases could be 

 given. They abound in the Lepidoptera: one of the most extra- 

 ordinary is that certain male butterflies have their fore-legs more 

 or less atrophied, with the tibiae and tarsi reduced to mere rudi- 

 mentary knobs. The wings, also, in the two sexes often differ in 

 neuration," and sometimes considerably in outline, as in the 

 Aricoris epitus, which was shown to me in the British Museum 

 by Mr. A. Butler. The males of certain South American butter- 

 flies have tufts of hair on the margins of the wings, and horny 



Fig. 9. Crabro crlbrarlus. Up- 

 per fignre, male; lower fig- 

 ure, female. 



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

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



« Kirby and Spence, 'Tntroduct.' &c., vol. ill. pp. 332-336. 



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



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

 I may add that the wings in certain Hymenoptera (see Shuckard, 

 'Fossorial Hymenop.' 1837, pp. 39-43) differ in neuration according to 

 sex. 



