PREFACE ix 



of gratitude for continual advice and criticism, and for 

 most efficient assistance in correcting proofs and verifying 

 references. 



I have attempted to express my indebtedness to Pro- 

 fessor Meldola, F.R.S., by dedicating this volume to him. 

 His writings were the original stimulus to which I owe 

 the work of my life, and during nearly a quarter of a 

 century devoted to that work I have relied probably even 

 more than I am myself aware upon his sympathy and 

 help. The great names of Darwin and Wallace are 

 associated with Meldola's in the dedication, thus express- 

 ing, although very insufficiently, my sense of an im- 

 measurable debt of gratitude. The life and immortal 

 work of Darwin are a heritage of inspiration to every 

 naturalist. To Alfred Russel Wallace I owe not only the 

 stimulus of epoch-making thoughts, but the incalculable 

 influence of long years of friendship and encouragement. 



EDWARD B. POULTON. 



Oxford, 

 March 31, 1908. 



