X INTRODUCTION. 



over the base of the culmen. Depth of bill is also measured with dividers, and is a 

 measurement requiring extreme care. Length of tarsus is measured with dividers, 

 one point resting in the tibio-tarsal joint, on the outer side, the other on the lower 

 edge of lowermost tarsal scutella, in front (in Passerine and certain Picarian and 

 Eaptorial birds), or to the more or less obvious transverse depression marking the 

 line of separation between tarsus and base of middle toe (in most water birds and 

 some others). Length of middle toe is always measured with dividers from the 

 last-mentioned point to the base of the claw, on top, and not including the claw, 

 unless so stated. 



Measurements of eggs represent the average of six specimens (more or less, ac- 

 cording to the extent of the series available for the purpose) which represent or 

 approximate the average size and form as nearly as could be determined by the eye 

 alone. 



The names oe colors used in the diagnoses are adopted from the author's " No- 

 menclature of Colors," 1 in which may be found an elaborate though concise treatise 

 on the subject, designed especially for the uses of the naturalist, and in which 186 

 colors, embracing all that are named in descriptive ornithology, are depicted, by 

 hand-colored plates. 



Illustrations. — With the exception of those which have already appeared in 

 the Review of American Birds' History of North American Birds, 1 and Water Birds 

 of North America* the illustrations have been made specially for the present work 

 by Mr. John L. Ridgway, under the author's supervision, and engraved by the cele- 

 brated " Jewett" process of Messrs. Matthews, Worthrupp & Co., of Buffalo, N.Y. 



Acknowledgments are specially due to Professor. Baird, not only for the 



1 A | Nomenclature of Colors | for Naturalists, | and | Compendium of Useful Knowledge | for Ornitholo- 

 gists. | By | Robert Ridgway, | Curator, Department of Birds, United States National Museum. | With ten 

 colored plates and seven plates | of outline illustrations. | Boston : | Little, Brown, and Company. | 188?. | 



[In this work is also embodied a " Glossary of terms used in descriptive ornithology," in which references 

 are given to all the plates. The latter include, besides those representing the colors, three showing the exter- 

 nal anatomy or " topography" of a bird, with special reference to the names used in descriptions, one illus- 

 trating various egg-contours, one showing a comparative scale of standard measurements, and two upon which 

 are depicted the various forms or patterns of feather-markings. There is also, among other things useful to 

 the naturalist, a series of tables for the easy conversion of inches and decimals into millimetres, and vice versa.] 



» Smithsonian Miscellaneous Collections. | — 181 — | Review | of American Birds, in the Museum of the | 

 Smithsonian Institution. | By | S. F. Baird. | — Part I. North and Middle America. | — [Medallion.] Wash- 

 ington : | Smithsonian Institution. | 



One volume, 8vo; date of publication (by signatures), June, 1864, to June, 1866. 



» A | History | of | North American Birds | by | S. V. Baird, T. M. Brewer, and R. Ridgway | Land Birds 

 | Illustrated by 64 colored plates and 593 woodcuts | Volume I [—III]. [Vignette.] | Boston | Little, Brown, 

 and Company | 1874. | 



[This is the most recent work on North American ornithology, giving, besides technical descriptions, 

 synonymy, etc., a general account of the history and habits of eaoh species, as known up to date of publica- 

 tion. The size is small 4to, and the total number of pages nearly 1800.] 



* Memoirs of the Museum of Comparative Zob'logy at Harvard College, Vols. XII. and XIII. The Water 

 Birds of North America. By S. F. Baird, T. M. Brewer, and R. Ridgway. Issued in continuation of the pub- 

 lications of the California Geological Survey. J. D. Whitney, State Geologist. Boston. Little, Brown, and 

 Company, 1884. 



[Two volumes, uniform in general style, typography, etc., with the " History of North American Birds," 

 and in reality the oonclus'ion of that work. Total number of pages 1104, embellished by numerous wood-cuts.] 



