308 OUNITIIOLOGY. 



In tlie preparation of this report, the vahied facilities afforded by the 

 Smithsonian Institution were availed of, through the courtesy and kindness 

 of Professor Joseph Henry, the Secretary of the Institution ; among the 

 many advantages thus secured being frequent access to a splendid working 

 library and an unrivaled collection of North American birds. The author 

 wislies also to express himself as particularly indebted to Professor Spencer 

 F. Baird, Assistant Secretary of the Smithsonian Institution and Curator of 

 the National Museum, for invaluable assistance kindly rendered throughout 

 the progress of the work. 

 I have the honor to be, 



Very respectfully, your obedient servant, 



ROBERT RIDGWAY. 

 Clarence King, E.sq., 



United States Geologist, 



In charge of U. S. Geological Explorations, 40th Parallel. 



