Mil INTRODUCTION. 



nient adopted by Mr. Salvin and myself in our 'Nomeuclator 

 Avium Neotropicalium,' published in 1873. It would have been 

 better, no doubt, in some respects to have attempted a thorough 

 revision of these groups; but I felt that the short time assigned to 

 me for the preparation of the present volume and the comparatively 

 little leisure I had to devote to it would not give me a chance of 

 performing this revision satisfactorily. This, therefore, I must 

 leave to some younger and better qualified worker to perform. 

 Nevertheless, after sorting the large material belonging to these 

 groups now in the Collection of the British Museum, and reducing 

 them into the order of the ' Nomenclator,' I feel that I have 

 accomplished a not unsatisfactory piece of work, and one that will 

 enable the ornithologist of the future, who may wish to take in hand 

 a real monograph of these difficult groups, to start with much 

 greater advantage. For myself I am content to have produced, not 

 a monograph, but a catalogue. 



The total number of specimens of Mesomyodian Passeres in the 

 Collection of the British Museum, as enumerated in the present 

 volume, is 7360. These I have referred to 665 species, leaving only 

 38 species recognized as probably valid, but unrepresented in the 

 Collection. The series of specimens is generally very complete, and 

 the range of the species is in most cases admirably shown by the 

 localities affixed to them. For this very valuable feature the 

 Museum is mainly indebted to the Salvin-Godman Collection, with 

 its unrivalled set of specimens directly obtained from the collectors. 



The number of actual " types " of species in the families treated of 

 in the present volume is 161, besides which there are a considerable 

 number of "authentic" specimens — that is, such as have been 

 obtained in the same locality and by the same collector as the types 

 themselves, and are accordingly of nearly equal value. 



I have now only to thank the many valued friends and corre- 

 spondents who have assisted me during the progress of the present 

 volume, both by the loan of specimens for comparison and by 

 affording me information on difficult points. Amongst these I must 

 specially mention the names of Dr. G. Hartlaub of Bremen, Herr 

 August von Pelzeln of Yienna, MM. Alphonse Milne-Edwards and 

 E. Oustalet of Paris, M. Taczanowski of Warsaw, Hans, Graf von 

 Berlepsch of Muendcn, Dr. F. A. Jentink of Leyden, Mr. Jouy 

 of Washington, and Sir Walter Buller. 



Mr. <!. X. Lawrence, of New York, was kind enough to send all 

 his types of Tyrannidce across the Atlantic for examination; and 



