Notice to Subscribers. 



Tn the present work the author, after much consideration, has decided to 

 follow the recommendations of the Fifth International Zoological Congress 

 with regard to nomenclature. While fully aware of the inconvenience 

 caused to those who have become accustomed to the names most commonly 

 in use among English naturalists, he is convinced that this drawback is 

 outweighed by the advantage of adopting the same system of nomenclature 

 which is in use among almost all other civilized nations. After all, the 

 main use of scientific nomenclature is to provide a common language for 

 scientists of all nations, and this can only be done by all agreeing to 

 accept one code of rules. For this reason the Tenth Edition of Linnaeus has 

 been adopted as the original standpoint instead of the Twelfth, although the 

 writer's personal preference would be for the latter work, as embodying 

 the matured judgment of the great Swedish naturalist. 



With regard to the recognition of geographical races, now that the 

 various forms of all the Pala?arctic species are being worked out by 

 Dr. Hartert in his work on the Birds of the Palsearctic Fauna, it becomes 

 for the first time possible to extend this study to the Oology of the Birds 

 of Europe. Hither to the usual practice among British naturalists has 

 been to elevate our local races to the rank of species (as in the case the 

 Motacilke and Pari), while at the same time entirely ignoring many equally 

 well marked continental races. For the nomenclature of these forms the 

 trinomial system has been adopted, as clearer and less open to confusion 

 than the binomial systems of Dr. Sharpe and Mr. Dresser. Possibly some 

 of the forms mentioned in this work may be thought scarcely sufficiently 

 well defined to require subdivision, and this may eventually prove to be 

 the case; but great care has been taken to avoid the lumping together of 

 statistics which apply to distinct races. 



For purposes of measurement the millimetre has been adopted as the Measure- 

 unit, in order to facilitate comparison with the statistics in continental ^^^ 

 works, and as being now in general use for scientific purposes. It should weights 

 be noted that the breadth of an egg is usually subject to much less 

 variation than the length, and is therefore a more reliable test. Where 

 sufficient material has been accessible a series of not fewer than 100 eggs 



