SELECTION AND COURTSHIP. 26 71 
hand, are the antlers of the stag, the tusks of the boar, the 
spur of the cock, and the hugely developed pair of jaws in 
the male stag-beetle ; all are instruments employed by the 
males in the struggle for the females, for annihilating or 
chasing away their rivals. 
In the cases just mentioned, it is the bodily “struggle to 
the death” which determines the origin of the secondary 
sexual characters. But, besides these mortal struggles, there 
are other important competitions in sexual selection, which 
no less influence the structure of the rivals. These consist 
principally in the fact that the courting sex tries to please 
the other by external finery, by beauty of form, or by a 
melodious voice. Darwin thinks that the beautiful voices 
of singing birds have principally originated in this way. 
. Many male birds carry on a regular musical contest when 
they contend for the possession of the females. It is known 
of several singing birds, that in the breeding season the 
males assemble in numbers round the females, and let their 
songs resound before them, and that then the females choose 
the singers who best please them for their mates. Among 
other songsters, individual males pour out their songs in the 
loneliness of the forest in order to attract the females, and 
the latter follow the most attractive calls. A similar musical 
contest, though certainly less melodious, takes place among 
crickets and grasshoppers. The male cricket has on its belly 
two instruments like drums, and produces with these the 
sharp chirping notes which the ancient Greeks curiously 
enough thought beautiful music. Male grasshoppers, partly 
by using their hind-legs like the bow of a violin against 
their wing coverings, and partly by rubbing their wing 
coverings together, bring out tones which are, indeed, not 
