8 PREFACE TO THIRD EDITION. 
Fifteenth) to the Check-List, published respectively in ‘The Auk’ for 
July, 1908, and July, 1909." 
The changes in nomenclature from the second edition are numer- 
ous, and result mainly from two causes: The recent unprecedented 
activity in bibliographic research, abroad as well as in America, and 
the strict application of the law of priority. ‘The critical examination 
of many little known or wholly overlooked early publications, and 
more careful scrutiny of others long well known, has led to the dis- 
covery of many generic and specific names that, under universally 
accepted rules of nomenclature, must be adopted. Many of these 
changes result from the tendency heretofore to ignore rules of nomen- 
clature when their observance entailed unwelcome changes in technical 
names. With each year, however, the tendency is toward a strict 
enforcement of generally accepted rules of nomenclature, the former 
indifference to such rules rapidly giving place to their strenuous 
observance, especially by the younger school of taxonomers. 
Many changes in generic names have resulted from raising to 
generic rank various groups recognized merely as subgenera in the 
first and second editions of the Check-List, their reduction in grade 
by the original Committee having failed to meet with general 
approval. 
The classification adopted for the Check-List a quarter of a century 
ago does not now reflect current views on the relationships of many 
1 Eight Supplements to the Check-List have been published since the appearance of 
the second edition, as follows: : 
Eighth Supplement to the American Ornithologists’ Union Check-List of North 
American Birds.— Auk, XIV, Jan., 1897, pp. 117-135. 
Ninth Supplement to the American Ornithologists’ Union Check-List of North Ameri- 
can Birds.— Auk, XVI, Jan., 1899, pp. 97-133. 
Tenth Supplement to the American Ornithologists’ Union Check-List of North Ameri- 
can Birds.— Auk, XVIII, July, 1901, pp. 295-320. 
Eleventh Supplement to the American Ornithologists’ Union Check-List of North 
American Birds.— Auk, XIX, July, 1902, pp. 315-342. 
Twelfth Supplement to the American Ornithologists’ Union Check-List of North 
American Birds.— Auk, XX, July, 1903, pp. 331-368. 
Thirteenth Supplement to the American Ornithologists’ Union Check-List of North 
American Birds.— Auk, XXI, July, 1904, pp. 411-424. 
Fourteenth Supplement to the American Ornithologists’ Union Check-List of North 
American Birds.— Auk, XXV, July, 1908, pp. 343-399. 
Fifteenth Supplement to the American Ornithologists’ Union Check-List of North 
American Birds.— Auk, XX VI, July, 1909, pp. 294-303. 
For a list of the previous Supplements see the Preface to the second edition of the 
Check-List (below, p. 15). 
