BEETLES THAT *^ BLUFF" 211 



dimorphism is also met with, it will be remembered, 

 among the Butterflies and Moths. 



While brilliant colour is the more usual form of orna- 

 ment among the Beetles, there are many species wherein 

 the males have developed enormous horns, or have greatly 

 exaggerated the length of the jaws ; and these outgrowths 

 give the impression of a formidable armature, but so far 

 as the evidence goes this is by no means the case. 

 They must therefore be relegated to the category of 

 " ornaments," though the term " excrescences " would 

 more fittingly apply to them, for they are " ornaments " 

 only from a human standpoint. At any rate, there is 

 no evidence whatever that they serve to enhance their 

 possessors in the eyes of the females. 



In relation to the Sexual Selection theory these 

 excrescences are of quite exceptional interest, for they 

 throw a strong light en the meaning of ornament, such 

 as obtains among birds, which seem to show a conscious- 

 ness of its existence and effectiveness. Darwin argued 

 from the birds to the Beetles. Convinced that the gorgeous 

 crests and trains and vivid colours were appreciated 

 by the females of the former, he was impelled to 

 believe that the ornaments of the latter had developed 

 in like case by the fostering influences of the females. 

 Similarly, from the evidence as to the use of horns in the 

 case of mammals, and spurs in the case of birds, he was 

 induced to believe that the horn-like outgrowths of Beetles 

 had been attained by like influences. But in both kinds 

 of cases, he could only infer their action, for he could 

 discover no really decisive instances of conquest either by 

 display or by battle, such as he was able to produce in 

 the case of the higher animals. Had chance directed 

 his attention in the beginning either to the Warblers 



Id* 



