ADVERTISEMENT. 
The extension of the scope of the National Museum during the past 
few years, and the activity of the collectors employed in its interest, 
have caused a great increase in the amount of material in its possession. 
Many of the objects gathered are of a novel and important character, 
and serve to throw a new light upon the study of nature and of man. 
The importance to science of prompt publication of descriptions of 
this material led to the establishment, in 1878, of the present series of 
publications, entitled ‘ Proceedings of the United States National 
Museum,” the distinguishing peculiarity of which is that the articles 
are published in pamphlet form as fast as completed and in advance 
of the bound volume. The present volume constitutes the fifteenth of 
the series. 
The articles in this series consist: First, of papers prepared by the 
scientific corps of the National Museum; secondly, of papers by others, 
founded upon the collections in the National Museum; and, finally, of 
facts and memoranda from the correspondence of the Smithsonian 
Institution. 
The Bulletin of the National Museum, the publication of which was 
commenced in 1875, consists of elaborate papers based upon the collec- 
tions 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 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 National Museum are referred to the Advisory Committee on Pub- 
lications, composed as follows: T. H. Bean (chairman), A. Howard 
Olark, R. E. Earll, Otis T. Mason, Leonhard Stejneger, Frederick W. 
True, and Lester F. Ward. 
S. P. LANGLEY, 
Secretary of the Smithsonian Institution. 
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