PREFACE. 



Wi rn the remarkable increase of the collection of Birds this volume 

 of the ' Catalogue ' has assumed a bulkier shape than any of its 

 predecessors. In fact, since the commencement of the work in 

 1874 the collection has been nearly trebled, so that the species 

 described in the present volume are represented on an average by 

 a series of about seventeen examples each. 



In the Preface to Volume X. it was my pleasing duty to place 

 on record the acquisition of two most important collections of 

 South-American Birds. These accessions were quickly followed 

 by the equally valuable gifts of two celebrated collections of Birds 

 of the Old "World — both formed by ornithologists who thoroughly 

 understood the requirements of modern Ornithology as -to the 

 methods and principles of collecting. 



The first of these donations is the collection formed by Allan 

 0. Hume, Esq., C.B., beyond comparison the most extensive, com- 

 plete, and important that has ever been formed of the birds of the 

 British Asiatic Empire. Beside the specimens obtained by the 

 donor himself and the collectors employed by him, this collection 

 embraces the Mandelli collection from Sikkim and Tibet, Brooks' 

 North-Western and Central-Indian Birds, Bingham's collection 

 from Delhi and Tcnasserim, Scully's collection from Turkestan, and 

 others. It consists of 63,000 bird-skins, 18,500 eggs, and 500 nests. 

 Many of the species, the number of which has been computed at 

 2000, are represented by long series very completely illustrating 

 their geographical distribution and variation according to age, season, 

 or locality. 



