conspicuous and familiar types of armature, but none of 

 them adequately account for the very diverse forms actually 

 existing, sometimes in one sex only, sometimes in identical 

 or in different forms in both sexes. 



Fabre (" Souvenirs Entomologiques ") has described the 

 wonderfully elaborate nidification, in which male and female 

 collaborate, of Copris hispanus and C. lunaris and Geotrupes 

 typhaeus, and has observed the employment of the horns by 

 the last. Probably if we knew the habits of other species 

 we should find the armature serving a variety of purposes. 

 In the absence of such information I have found useful evidence 

 in the presence or absence of wear in the digging teeth of the 

 front tibiae of male and female respectively. When the two 

 sexes co-operate the average amount of wear is the same in 

 both; in others the examination of a considerable number 

 of specimens shows the wear confined to the females, and in 

 one interesting case, Corynoscelis glaucon, Perty, a Dynastid 

 curiously resembling the very remote Geotrupes typJiaeus, it 

 is markedly greater in the male. In many of the giant forms 

 there is a great elongation, and consequently reduced muscu- 

 larity, of the legs of the males. 



Such evidence seems to me to indicate that in the very 

 numerous species in which there is an armature in both sexes 

 or in which that of the male is not extravagantly developed, 

 there is collaboration between the sexes, but that when the 

 male is fantastically horned it is invariably a drone, bearing 

 no part in nidification. In the former case the development 

 is restrained by the operation of Natural Selection, which in 

 the latter, while suppressing awkward outgrowths in the female, 

 has had no such effect upon the comparatively unimportant 

 male. It is perhaps not impossible that the conspicuousness 

 of the male of the horned giants, frequently also manifested 

 in these cases in a more brilliant exterior, may by attracting 

 enemies to itself help to save the more important female and 

 so become beneficial to the race. 



Fabre's discovery of the existence of a prothoracic pro- 

 tuberance in the pupae of both sexes in the genus Onthophagus, 

 although he was entirely wrong in declaring it to have no 

 counterpart in adult beetles, appears to me to have great 



