VI BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



The manuscript of the present volume was completed in 1936 and 

 was revised and brought up to date in 1940, again in 1945, and, for 

 the last time, in February to May 1948. Just before going to press 

 in August 1949 a few changes were made to bring it in line with 

 changes suggested by Hellmayr and Conover, page proofs of whose 

 volume were kindly sent me for that purpose. 



Measurements of specimens for use in the preparation were made 

 by the author and by A. L. O'Leary, under the author's supervision. 

 The late Maj. Allan Brooks contributed (before the present author 

 began this work) a series of notes on the colors of the unfeathered 

 parts of many of the species discussed herein. The outline drawings 

 of generic details, except those previously published, were made 

 partly by E. R. Kalmbach, and partly, under the author's supervision, 

 by Mrs. Aime M. Awl, of the United States National Museum staff. 

 Compilation of literature references was done by the author witli 

 some assistance from the late J. H. Rile}^ and from Dr. E. M. Has- 

 bro uck. 



Herbert Friedmann. 



