^,,, PREFACE. 



•■s(i(MK-(^ is not literature,'^ neither has it any eoncern with what an 

 author should have done or meant to do, but only with what he 



actually did. 



Without the special arrangements for the preparation of this work 

 made hy the late Dr. G. Brown Goode (as mentioned at the beginning 

 of this preface) and contiiuied by his successors, Dr. Charles D. Wal- 

 i-ott and :^Ir. Richard Kathluui, the accomplishment of the task would 

 have been quite impracticable. These arrangements, it should be 

 stated, are all that are possible under existing circumstances, though 

 by no means all that could be desired for its early completion. 



Notwithstanding the great extent of the collection of birds in the 

 United States National Museum, which is much the largest and most 

 nearly complete of any in America, and of North American birds 

 luiquestionably the finest in existence, so many groups are inadequately 

 rcprescMited that it has been necessary to borrow specimens from other 

 collections for study in connection with this work. It is a great pleas- 

 ure to the author that he is able to say that such aid has, almost with- 

 out excei)tion, been most willingly and promptly rendered by those 

 having it in their power to do so. The unrivaled collection of Mexican 

 l)irds,* as well as very numerous specimens from the United States 

 (including Alaska) and the British Provinces, belonging to the United 

 States Biological Survey (Department of Agriculture) has been kindly 

 placed in the author's hands for study by the Director of the Survey, 

 Dr. C. Hart Merriam. The entire collection of each famil}^ belonging 

 to the American Museum of Natural History, New York City, has 

 been lent for the same purpose, whenever requested,*^ by the authori- 

 ties of that institution, through Dr. J. A. Allen, Curator of the Depart- 

 ment of Vertebrate Zoology, these including many types of Mr. George 

 N. Lawrence, so essential to any investigation of the birds of tropical 

 America. The Academ}^ of Natural Sciences of Philadelphia, through 



' For tlii.s inagiiificent collection of Mexican birds ornithologists are indebted to 

 the intelligent and energetic labors of Mr. E. W. Nelson, whose caivfnl, thorough, 

 and protracted field work has covered nearly every portion of that most interesting 

 section of the continent. It illustrates, to a degree which no other collection from 

 tliat country approaches, the remarkal)le variations, often within small areas, mani- 

 fest in many of the birds, resulting from unusually varied topographic features and 

 climatic conditions. Without a careful study of Mr. Nelson's collection, wdiich 

 int-ludes the types of numerous new^ species and sul)species described by him, a fairly 

 accurate knowledge of the geographic distril)ution and variations of Mexican birds 

 would not ])e possible. The inestimable value of this collection in the preparation 

 of the jtresent work lias l)een greatly enhanced l)y Mr. Nelson's kind assistance, both 

 verlially and by means of a ma]), colored by him to show the different faunal areas, 

 thereby exi)laining most clearly why marked variations often occur in birds of locali- 

 ties not far separated as to distance but in reality very different in physical character. 



'■'These include, to date, their entire representation of the families of Fringillidtc, 

 Icteridte, and Corvida^. 



