ADVERTISEMENT. 



This work (Special Bulletin No. 2) is one of a series of papers intended to illustrate tlie 

 collections belonging to, or placed in 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. 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 Bulletin is 

 issued only in volumes. Most of the volumes hitherto published have been octavos, but a 

 quarto form has been adopted for works of the size and character of the present Bulletin, 

 this being No. 2 in the quarto series. 



The Bulletin of the United States National Museum, the publication of which was 

 commenced in 1S75, consists of elaborate papers based upon the collections of the Museum, 

 reports of expeditions, etc. The Proceedings are intended to facilitate the prompt publi- 

 cation of freshly acquired facts relating to biology, anthropology, and geology, descriptions 

 of restricted groups of animals and plants, discussions of particular 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. 



Papers intended for publication in the Proceedings and Bulletin of the United States 

 National Museum are referred to the advisory committee on publications, composed as 

 follows: Frederick W. True (chairman), It. Edward'Earll (editor), James E.Benedict, Otis 

 T. Mason, Leonhard Stejueger, and Lester E. Ward. 



S. P. Langley, 

 /Secretary of the Smithsonian Institution. 



Washington, D. C, June 3, 1S95. 



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