viii Preface. 



potheses. Some of the results of these endeavours 

 are presented in this volume, which, if it has no other 

 value, may claim this : that it describes, as far as I 

 can, observations and enquiries undertaken with a 

 desire for knowledge only, and to satisfy myself, and 

 with no notion of writing a book. 



The question may well be asked : why, then, do 

 you write a book ? My answer is that science is 

 surely aided by any demonstration of unity in type 

 or tendency where before only differences and varieties 

 were observed and distinguished. Since, I believe, 

 against some great authorities, that our common 

 cuckoo (Cuciilus canonis) is far more intimately re- 

 lated to the two best-known American cuckoos and 

 to several others of India and elsewhere than has yet 

 been demonstrated, I crave for permission to put my 

 demonstration before those who may be presumed to 

 be interested in it, and to leave the matter with them. 

 I have scorned no pains to make it complete. 



The reader will find as he proceeds that the single 

 species — our cuckoos — soon leads to questions of 

 larger interest — questions, indeed, of the highest 

 scientific interest, in which not only birds, but many 

 other species are more or less involved. 



I have to thank Dr. Bowdler Sharpe and Mr. 

 Saunders at South Kensington for aid, and Mr. E. 

 Bidwell for much ready assistance ; Dr. Richard 



