372 
SEXUAL SELECTION. 
Part li- 
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 
body, yet in the females a rudiment of a single horn on 
the head (fig. 21, a), and of a crest (b) on the thorax, 
are plainly visible. That the slight thoracic crest in the 
Fig. 21. Left-band figure, male of Onitis furcifer, viewed laterally. Right-hand figu re 
female. a. Rudiment of cephalic horn. &. 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 
horns on the upper surface of the 
