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 thirteenth of 

 the series. 



The articles in this series consist : First, of pa])ers 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 In- 

 stitution. 



The Bulletins of the National Museum, the publication of which was 

 commenced in 1875, consist of elaborate papers based upon the collec- 

 tions of the Museum, reports of expeditious, 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 exi)editious. 



Other papers, of more general popular interest, are printed in the 

 Appendix to the Annual Report. 



Papers intended for publication in the Proceedings and Bulletins of 

 the National Museum are referred to the Committee on Publications, 

 composed as follows : T. H. Bean, A. Howard Clark (editor), R. E. Earll, 

 Otis T. Mason, John Murdoch, Leonhard Stejneger, Frederick W. True, 

 and Lester F. Ward. 



S. P. Langley, 

 \ Secretary of the S^nithsoiiian Institirtion. 



