214 



INTRODUCTION. 



by their extreme variability in the same species, and by their 

 extensive diversity in closely allied species — is that they have 

 " been acquired as ornaments. This view will at first appear 

 extremely improbable, but we shall hereafter find with many 

 animals standing much higher in the scale, namely, fishes, amphi- 

 bians, reptiles, and birds, that various kinds of crests, knobs, 

 horns, and combs have been developed apparently for the same 

 purpose." 



Fig. 96. — Xylotrupes gideon. Larva x |. (After Schiodte.) 



We very much doubt this theory, and it is possible that there 

 may be no explanation further than the fact that these growths 

 are the outcome of a cell-stimulus of which at present we know 

 nothing. 



These gigantic species, in spite of their formidable appearance,, 

 are quite harmless. They are mostly nocturnal or crepuscular in 

 their habits, and live in the hollows of old trees, feeding on 

 exuding sap. Their colouring, therefore, is mostly of a sombre 

 description, black or brown ; one fine Indian species, Chalcosoma 

 atlas, is plainly, but not strongly, metallic. 



