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 nionographic 

 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 onty 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 

 L878, 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, etc. 

 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 visually 

 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. LANGLEY, 

 Secretary of the Smithsonian Institution. 



WASHINGTON, U. S. A., April 4, 



