The Evidence from Sexual Characters. 199 



the summit of this appendage, and in a third species the 

 whole appendage is converted into a horn. In the fe- 

 males of all these species and in the young males the ap- 

 pendage is very minute. The male Chameleon bifurcus 

 has two great solid bony projections, covered with scales, 

 in the upper part of the skull. The male Chameleon 

 Owenii has three great bony horns on his head. These 

 bony horns are covered with a smooth sheath of integu- 

 ment, so that they are strikingly like those of a bull or 

 a goat. In the females and young of both species these 

 appendages are rudimentary." 



BIRDS. The sexual characteristics of birds are most 

 diversified and conspicuous, and most persons, even those 

 who are not naturalists, know enough of this subject 

 to agree that the males are as a rule much more modi- 

 fied than the females, and it will not be necessary to de- 

 vote very much space to this group. Darwin has de- 

 voted more than, two hundred pages to the discussion of 

 the differences between male and female birds, and he has 

 brought together an array of facts all tending to show 

 that male modification is the rule, while female modifi- 

 cation is comparatively rare, and although it is true that 

 lie gives another explanation of the phenomena, an ex- 

 planation which will be discussed in the next chapter, yet 

 every reader of his essay must be convinced of the cor- 

 rectness of his conclusion, p. 227, " that weapons for bat- 

 tle, organs for producing sound, ornaments of many 

 kinds, bright and conspicuous colors, have generally been 

 acquired by the males, . . . the females and the 

 young being left comparatively but little modified." 



This conclusion will be accepted without question by 

 all who arc familiar with the subject, and it is hardly 

 necessary to dwell upon it, but the great diversity of the 

 sexual differences in birds demands that in a general 



