Many who have contributed material for previous Bulletins have continued to cooperate. Receipts of material from several hundred contributors has been acknowledged in previous Bulletins. In addition to these, our thanks are due to the following new contributors: G. A. Ammann, O. L. Austin, Jr., F. S. Barkalow, Jr., Ralph Beebe, H. E. Bennett, A. J. Berger, Virgilio Biaggi, Jr., C. H. Blake, Don Bleitz, B. J. Blincoe, L. C. Brecher, Jeanne Broley, Maurice Broun, J. H. Buckalew, I. W. Burr, N. K. Carpenter, May T. Cooke, H. L. Crockett, Grace Crowe, Ruby Curry, J. V. Dennis, E. von S. Dingle, M. S. Dunlap, J. J. Elliott, A. H. Fast, Edith K. Frey, J. E. Galley, J. H. Gerard, Lydia Getell, H. B. Goldstein, Alan Gordon, L. I. Grinnell, Horace Groskin, F. G. Gross, G. W. Gullion, E. M. Hall, R. H. Hansman, Katharine C. Harding, H. H. Harrison, J. W. Hopkins, N. L. Huff, Verna R. Johnston, Malcolm Jollie, R. S. Judd, M. B. Land, Louise de K. Lawrence, R. E. Lawrence, G. H. Lowery, J. M. Markle, C. R. Mason, D. L. McKinley, R. J. Middleton, Lyle Miller, A. H. Morgan, R. H. Myers, W. H. Nicholson, F. H. Orcutt, H. L. Orians, R. A. O'Reilly, A. A. Outram, G. H. Parks, K. C. Parkes, M. M. Peet, J. L. Peters, F. A. Pitelka, Mariana Roach, James Rooney, Jr., O. M. Root, G. B. Saunders, James Sawders, Mary C. Shaub, Dorothy E. Snyder, Doris Heustis Speirs, E. A. Stoner, P. B. Street, H. R. Sweet, E. W. Teale, A. B. Williams, G. G. Williams, R. B. Williams, Mrs. T. E. Winford, and A. M. Woodbury. As the demand for these Bulletins is much greater than the supply, the names of those who have not contributed to the work during recent years will be dropped from the author's mailing list. Dr. Winsor M. Tyler has again read and indexed for this volume a large part of the current literature on North American birds and has contributed four complete life histories. Dr. Alfred O. Gross has written stories on the yellow-throats (_Geothlypis trichas_) and has contributed three other complete life histories. Edward von S. Dingle, Alexander Sprunt, Jr., and Dr. Josselyn Van Tyne have contributed two complete life histories each. INTRODUCTION William George F. Harris has increased his valuable contribution to the work by producing the entire paragraphs on eggs, including descriptions of the eggs in their exact colors, assembling and averaging the measurements, and collecting and arranging the egg dates, as they appear under Distribution; the preparation of this last item alone required the handling of over 5,600 records.