ADVERTISEMENT. 
This work is the thirty-first of a series of papers intended to illus- 
trate the collections of natural history and ethnology belonging to the 
United States, and constituting the National Museum, of which the 
Smithsonian Institution was placed in charge by the act of Congress 
of August 10, 1846. 
It has been prepared at the request of the Institution, and printed by 
authority of the honorable Secretary of the Interior. 
The publications of the National Museum consist of two series—the 
Bulletins, of which this is No. 25, in continuous series, and the Pro- 
ceedings, of which the sixth volume is now in press. 
The volumes of proceedings are printed signature by signature, each 
issue having its own date, and a small edition of each signature is dis- 
tributed to libraries promptly after its publication. 
From time to time the publications of the Museum which have been 
issued separately are combined together and issued as volumes of the 
Miscellaneous Collections. These are struck off from the stereotype 
plates from which the first edition was printed, and in this form are 
distributed by the Smithsonian Institution to libraries and scientific 
societies throughout the world. Volume 13 of these collections includes 
Bulletins 1 to 10 inclusive; volume 19, vols. 1 and 2 of the Proceedings; 
volume 22, vols. 3 and 4 of the Proceedings; and volume 23, Bulletins 
11 to 15 inclusive. 
Full lists of the publications of the Museum may be found in the cur- 
rent catalogues of the publications of the Smithsonian Institution. 
SPENCER F. BAIRD, 
Secretary of the Smithsonian Institution. 
SMITHSONIAN INSTITUTION, 
Washington, June 1, 1884. 
