HISTORICAL PEEFACE. xxix 



and throughout the work liave unah'zed species under tlieir respective genera, these 

 under their subfainiHes or families, and these again under their orders. 



Part IV. consists of a Synopsis of the Fossil birds of North America, corresponding 

 to the appendix of the old " Key," but augmented by later discoveries. As before, this 

 part of the work has been revised by Professor O. C. Marsh. 



In the mechanical execution of the work, it has been my aim to compress the most 

 matter into the least space and leave no waste paper, in order to keep the treatise within 

 a single portable volume of convenient text-book size. I judge that there is nearly four 

 times as much matter in the present volume as there was in the original edition, the 

 page being much more closely printed, in a smaller type, and on thinner paper. 



The old " Key " was insufficiently illustrated, and the average character of the cuts 

 was not entirely satisfactory. The present edition more than doubles the number of 

 illustrations. These are in part original, in part derived from various sources, all of 

 which are duly accredited in the text. The basis of the series is of course the cuts of the 

 former edition ; but many of these have been discarded and replaced by better ones. 

 About fifty of the most effective engravings were secured by my publishers from Brehm's 

 " Thierleben ; " nearly as many more are from Dixon's " Rural Bird Life," the American 

 edition of which is owned by the same firm. A few have been copied from D. G. Elliot's 

 " Birds of America," and a few others from the Proceedings of the Zoological Society of 

 London. About fifty of the prettiest ones were drawn by Mr. Edwin Sheppard and en- 

 graved by Mr. H. H. Nichols, expressly for this edition. Another set — how nmiiy there 

 are of them I do not know — are from my own drawings, and have mostly appeared in 

 other of my publications. Several of Mr. E. Ridgway's drawings have been placed at my 

 service, through his kind attentions, and with Professor Bau'd's permission. I am in- 

 debted to Dr. E. AV. Shufeldt, U. S. A., for about thirty original anatomical drawings, as 

 well as for the colored frontispiece. Mr. Henry W. Elliott has kindly put at my dis- 

 position several of his own artistic compositions, and I have received some very beautiful 

 engravings with the compliments of the Century Company of New York. 



It is always agreeable to pay one's respects when due, and acknowledge assistance 

 and encouragement received in the preparation of one's books. Yet what an embarrass- 

 ment is mine now ! For there is no writer of repute on North American ornithology, 

 and scarcely a leader of the science at large, who has not assisted in the making of the 

 " Key ; " and there is no reader of the work who has not encouraged its author to produce 

 this new edition. I am trebly in debt, — to thousands whose names I know not ; to 

 hundreds I only know by name and fame ; to scores of tried and trusted friends. 



But let me say how much I am indebted to my compositors and proof-readers of the 

 (Jniversity Press at Cambridge for the skill with which they have turne'd copy into print, 

 and to the proprietors of that justly-celebrated establishment for the pains they have 

 taken in making the book an example of beautiful and accurate typography. Let me 

 recognize here the liberality and generosity of my friend, Mr. Dana Estes, senior of the 

 firm of Estes and Lauriat, in permitting me to make the book to suit myself, and in 

 sparing no expense to which he might be put in consequence. Let me not forget that 

 during its preparation, as for many years previously, I have enjoyed to tlie fullest extent 

 the privileges of the Smithsonian Institution and the National Museum, through the 

 courtesy of Professor Baird, my access to the great collection of birds being always facili 



