This work (Bulletin No. 47) is one of a series of papers intended 

 to illustrate the collections belonging to the United States, and 

 constituting the National Museum, of which the Smithsonian Insti- 

 tution was placed in charge by the act of Congress of August 10, 

 1846. 



The publications of the National Museum consist of two series 

 the Bulletins, of which this is No. 47, in continuous series, and the 

 Proceedings, of which the eighteenth volume is now in press. A 

 small edition of each paper in the Proceedings is distributed in 

 pamphlet form to specialists, in advance of the publication of the 

 bound volume. 



The Bulletins of the National Museum, the publication of which 

 was commenced in 1875, consist of elaborate papers based upon the 

 collections of the Museum, reports of expeditions, etc., while the 

 Proceedings facilitate the prompt publication of freshly-acquired 

 facts relating to biology, anthropology, and geology, descriptions 

 of restricted groups of animals and plants, the discussion of par- 

 ticular questions relative to the synonymy of species, and the diaries 

 of minor expeditions. 



Other papers, of more general popular interest, are printed in the 

 Appendix to the Annual Report. 



Full lists of the publications of the Museum may be found in 

 the current catalogues of the publications of the Smithsonian 

 Institution. 



Papers intended 6r publication in the Proceedings and Bulletins 

 of /the r^T^imal ;Museum are referred to the Committee on Publi- 

 cations, composed r as follows : FREDERICK W. TRUE (chairman), 

 R. EDWARD EARLL (editor), J. E. BENEDICT, OTIS T. MASON, 

 LEONHARD STEJNEGER, and LESTER F. WARD. 



S. P. LANGLEY, 

 Secretary of the Smithsonian Institution. 



WASHINGTON, D. C., 



March 18, 1896. 



