3? 



SEXUAL 



DIMORPHISM 



IN THE 



ANIMAL KINGDOM 



THEORY OF THE EVOLUTION OF SECONDARY 

 SEXUAL CHARACTERS 



BY 



J. T. CUNNINGHAM, M.A. 



FORMERLY FELLOW OF UNIVERSITY COLLEGE, OXFORD J AUTHOR OF 'MARKETABLE 

 MARINE FISHES OF THE BRITISH ISLANDS.' 



WITH THIRTY-TWO ILLUSTRATIONS 





LONDON 



ADAM AND CHAELES BLACK 



1900 



