372 



SEXUAL SELECTION. 



Part II. 



the same species and by their extreme 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, amphibians, reptiles and birds, that various 

 kinds of crests, knobs, horns and combs have been 

 developed apparently for this sole purpose. 



The males of Onitis furcifer (fig. 20) are furnished 

 with singular projections on their anterior femora, and 



with a great fork or pair of horns on 

 the lower surface of the thorax. This 

 situation seems extremely ill adapted 

 for the display of these projections, 

 and they may be of some real ser- 

 vice ; but no use can at present be 

 assigned to them. It is a highly 

 remarkable fact, that although the 

 Fig. 2o. onitis furcifer male, mal eg do t ^^bit even a trace of 



viewed from beneath. 



horns on the upper surface of the 

 body, yet in the females a rudiment of a single horn on 

 the head (fig. 21, a), and of a crest (6) on the thorax, 

 are plainly visible. That the slight thoracic crest in the 



& 



Fig. 21. Left-hand figure, male of Onitis furcifer, viewed laterally. Pdght-hand figure, 

 female. a. Rudiment of cephalic horn. b. Trace of thoracic horn or crest. 



female is a rudiment of a projection proper to the male, 

 though entirely absent in the male of this particular 

 species, is clear : for the female of Bubas bison (a form 



