viii British Diving Ducks 
no pictures of special interest to help the descriptions, except some interesting ones 
of eclipse plumages. Mr. Booth, too, in his excellent Rough Notes^ gives us some 
pictures of immatures, but they are also few in number, and do not deal with the 
rarer species. Of recent years I have discovered only one collection which con- 
tains many specimens of rare Arctic and Palaearctic ducks. This belongs to 
Mr. E. Lehn Schioler, of Copenhagen, and I cannot thank him too sincerely for the 
generous way in which he has placed his specimens at my disposal. When he 
found another ornithologist as anxious as himself to unravel the tangled skein of 
duck life, he immediately extended the hand of welcome, and lent to me any birds 
I required to fill the missing gaps. Thus I was able to complete my series without 
further search. As an instance of Mr. Schioler's thoroughness, I may state that on 
asking to see Eiders and King-Eiders, he at once produced eleven hundred speci- 
mens of these birds, which took us three days to examine. Another ornithologist 
to whom I owe a debt of gratitude is Rev. F. C. R. Jourdain, whose knowledge 
of the local distribution and the nests and eggs of European birds is second to none 
in Europe. He has most kindly given me many valuable notes on migration and 
the breeding habits and distribution of our ducks, as well as exact measurements of 
their eggs, and has saved me much work in the examination of Continental records. 
I am also grateful to the following friends for many useful notes and observa- 
tions : the Hon. Gerald Legge, Lord William Percy, Mr. Maurice Portal, Mr. 
Heatley Noble, Mr. H. St. Quintin, and Mr. Hugh Wormald. These are all men 
gifted with unusual powers of observation, whose records we can trust, and whose 
opportunities for studying ducks have been exceptional. Some of them have been 
my regular correspondents for many years, and all are imbued with a great love 
of ducks, so that if I can make these volumes acceptable to all such serious 
students of this subject I shall be very happy. 
Mr. Archibald Thorburn has again assisted me in the illustrations, and, with 
his usual skill and thoroughness, has achieved some remarkable work. Especial 
care has been taken in depicting the "soft" parts of the birds, as well as the natural 
surroundings of each species, and without this we cannot hope to have accuracy. 
Every drawing by Mr. Thorburn is a finished unit, perfect alike in harmony of 
colour and accuracy of drawing, and I trust that my readers will appreciate the 
