ADAPTATION FOR THE SPECIES 1 33 



colored much like the common Leghorns. Shades of 

 red and yellow decorate his neck and back, while the 

 flight feathers of his wings and of his tail and the 

 sickle feathers which ornament the rear of his back 

 and hang over his tail are lustrous dark green. The 

 hen meanwhile is very much less brilliant in her con- 

 trasts. I shall speak more fully of this in discussing 

 polygamy. 



The attraction of beauty is not the only lure by 

 which a creature may win its mate. Sound may cap- 

 tivate as effectively as beauty. This is true of insects 

 as well as of birds. Certain insects at least advise 

 their mates of their presence by means of a sound 

 which they emit. This is particularly noticeable 

 among the group of straight-winged insects to which 

 the grasshopper, katydid and cricket belong. The 

 grasshopper has a ridge on the angle of his wing and 

 a roughness on the side of his leg. When these two 

 are rubbed together the result is sometimes a fiddling, 

 sometimes a snapping or cracking sound, differing in 

 different grasshoppers. I doubt not these sounds are 

 pleasing to the female of the species, for they are al- 

 ways made by the male. The katydid, instead of fid- 

 dling in this way, has a sort of drum on the angle 

 of his one wing, which he can rub over a tooth in 

 the corresponding angle of his other wing, thus pro- 

 ducing the familiar "katydid" sound. I have never 



