Darwin's Theory of Sexual Selection 183 
Darwin compares them to the horns of stags and of the 
rhinoceros. They “are wonderful from their size and 
shapes.” Darwin offers the following conjecture as to their 
meaning: “The extraordinary size of the horns, and their 
widely different structure in closely allied forms, indicate 
that they have been formed for some purpose; but their 
excessive variability in the males of the same species leads 
to the inference that this purpose cannot be of a definite 
nature. The horns do not show marks of friction, as if used 
for any ordinary work. Some authors suppose that as the 
males wander about much more than the females, they re- 
quire horns as a defence against their enemies; but as the 
horns are often blunt, they do not seem well adapted for 
defence. The most obvious conjecture is that they are 
used by the males for fighting together; but the males have 
never been observed to fight; nor could Mr. Bates, after a 
careful examination of numerous species, find any sufficient 
evidence, in their mutilated or broken condition, of their hav- 
ing been thus used. If the males had been habitual fighters, 
the size of their bodies would probably have been increased 
through sexual selection, so as to have exceeded that of the 
females; but Mr. Bates, after comparing the two sexes in 
above a hundred species of the Copridz, did not find any 
marked difference in this respect amongst well-developed 
individuals. In Lethrus, moreover, a beetle belonging to 
the same great division of the lamellicorns, the males are 
known to fight, but are not provided with horns, though their 
mandibles are much larger than those of the female.” 
«The conclusion that the horns have been acquired as orna- 
ments is that which best agrees with the fact of their having 
been so immensely, yet not fixedly, developed, —as shown 
by their extreme variability in the same species, and by their 
extreme diversity in closely allied species. This view will at 
first appear extremely improbable; but we shall hereafter 
find with many animals standing much higher in the scale, 
