ADVERTISEMENT. 
This work (Bulletin No. 51) is one of a series of papers intended to 
illustrate the collections belonging to or placed under the charge of 
the Smithsonian Institution and deposited in the United States National 
Museum. 
The publications of the National Museum consist of two series—the 
Bulletin and the Proceedings. 
The Bulletin, publication of which was commenced in 1875, is a 
series of elaborate papers issued separately and based for the most 
part upon collections in the National Museum. They are monographic 
in scope and are devoted principally to the discussion of large zoolog- 
ical groups, bibliographies of eminent naturalists, reports of expedi- 
tions, etc. The bulletins, issued only as volumes with one exception, 
are of octavo size, although a quarto form, known as the Special Bul- 
letin, has been adopted in a few instances in which a larger page was 
deemed indispensable. 
The Proceedings (octavo), the first volume of which was issued in 
1878, are intended primarily as a medium of publication for newly 
acquired facts in biology, anthropology, and geology, descriptions of 
new forms of animals and plants, discussions of nomenclature, ete. 
A volume of about 1,000 pages is issued annually for distribution to 
libraries, while a limited edition of each paper in the volume is printed 
and distributed in pamphlet form in advance. 
In addition, there are printed each year in the second volume of the 
Smithsonian Report (known as the Report of the National Museum) 
‘papers, chiefly of an ethnological character, describing collections in 
the National Museum. 
Papers intended for publication by the National Museum are usually 
referred to an advisory committee, composed as follows: Frederick 
W. True (chairman), William H. Holmes, George P. Merrill, James 
E. Benedict, Otis T. Mason, Leonhard Stejneger, Lester F. Ward, and 
Marcus Benjamin (editor). 
S. P. Laneiey, 
Secretary of the Smithsonian Institution. 
Wasuineton, U.S. A., April 4, 1902. 
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