XXIV INTRODUCTION. 



upheld upon fixed principles by sucli rules as those above 

 mentioned. In the present case, therefore, an attempt has 

 been made to rectify the nomenclature of all the species which 

 have found their way into the British list, by presenting the 

 reader with the oldest, as far as could be ascertained, and 

 therefore the most correct name for each, coupled with the 

 name of the author who first bestowed it. 



The same principle has been applied, although less satis- 

 factorily, to genera; and, for the sake of simplicity, the adop- 

 tion of subgenera has been as much as possible avoided. It 

 may be further observed that, although in the main the syste- 

 matic arrangement here followed is that adopted by Yarrell, 

 it has been deemed expedient to introduce therein certain 

 modifications which have become necessary from an extended 

 knowledge of the species dealt with. The Orioles, for ex- 

 ample, as also the Rock Thrushes, have been separated from 

 the true Thrushes, with which Yarrell had associated them. 

 The Tree Creeper and Common Wren, hitherto placed 

 amongst the Scansorial birds in company with the Wryneck 

 and other zygodactyle forms, have been removed to a position 

 more in accordance with their structure and habits. The 

 Plovers and Sandpipers, between which families Yarrell in- 

 terposed the Cranes, Herons, and Storks, have been brought 

 into close proximity from a due consideration of their natural 

 affinities ; and in a similar manner other families and genera 

 have been dealt with. In all cases where Yarrell's work is 

 quoted, the pages indicated are those of the 3rd and last 

 edition of 1856, the publication of the 4th edition by Pro- 

 fessor Newton having only recently commenced. 



In conclusion, it may be observed that, as the present work, 

 from its nature, cannot be expected to be free from mistakes, 

 any corrections or emendations which may be communicated 

 by the reader will be gratefully received by the author. 



