iv PEEFACE. 



they endeavoured to enumerate the characters which were sufficient to determine the genus, 

 leaving out of the diagnosis other characters, which may be very interesting and very 

 important, but are not absolutely necessary. Modern ornithologists belong to two schools ; 

 those belonging to the old school (than whom no better example can be found than Yarrell) 

 simply enumerate the so-called structural characters, leaving the reader to find out for 

 himself, if he can, which of them are diagnostic. No great fault can be found with this 

 mode of procedure, except perhaps that it may be regarded as an attempt to " play for 

 safety," which not unfrequently proves a great incentive to the use of strong language on 

 the part of the bewildered but irascible student, who tries in vain to determine the 

 genus of a strange bii'd. 



Dresser, in his ' Birds of Europe,' has adopted a most original course : he has simply 

 catalogued the structural characters of the type of each genus, without pointing out which 

 of them are common to all the species, and which of them are exceptional ; and, of the 

 former, without a hint as to whether they are common to allied genera, or are diagnostic 

 of the genus the type of which he is describing. 



The new school of modern ornithologists (of whom Ridgway and Sharpe may be 

 accepted as typical examples) boldly take the bull by the horns, and attempt to construct 

 diagnostic keys to the genera. They may or may not be successful, — unfortunately many 

 of these keys are lamentable failures, and will not turn in the lock ; but all honour to the 

 men who at least try to give definiteness to our knowledge. 



My thanks are due to many ornithologists for much valuable assistance. Firstly, to 

 Mr. Harting, for allowing me free access to his notes, and for permitting me to undertake, 

 with his help, a work upon a group of birds with which his name has been so lono- 

 associated; secondly, to Mr. Sharpe and the other officials of the British Museum, for 

 giving me access to the National Collections, even during the interregnum and semi-chaos 

 of the incorporation of the Hume collection ; thirdly, to Messrs. Salvin and Godman, for 

 the loan of rare birds from South America ; and, fourthly, to the Smithsonian Institution 

 in Washington, for the loan of equally rare birds from the Pacific Islands. 



It only remains for me to explain the use which I have endeavoured to make of these 

 and other materials to which I had access— to give, in short, a resume of the points of view 

 from which the Geographical Distribution of these birds may be studied. 



After having written a book, to add a preface in order to tell the reader the conclusion 

 at which it was intended to arrive, looks very much like the action of the leo-endary little 

 boy who made a picture of a quadruped with long ears, and then wrote under it " This is a 

 donkey." The little boy was not quite sure that a stranger would recognize his pictorial 

 efforts— not that he had any doubt as to the intelligence of the stranger, but because he 

 mistrusted his own powers of representation. 



The object which I set before me was to try and discover the origin of the various 



