ADVERTISEMENT. 



The scientific publications of the National Museum consist of two 

 series — Proceedings and Bulletins. 



The Proceedings, the first volume of which was issued in 1878, are 

 intended primarily as a medium for the publication of original papers 

 based on the collections of the National Museum, setting forth newly 

 acquired facts in biology, anthropology, and geology derived there- 

 from, or containing descriptions of new forms and revisions of limited 

 groups. A volume is issued annually or oftener for distribution to 

 libraries and scientific establishments, and, in view of the importance 

 of the more prompt dissemination of new facts, a limited edition of 

 each paper is printed in pamphlet form in advance. The dates at 

 which these separate papers are published are recorded in the table 

 of contents of the volume. 



The present volume is the fifty-first of this series. 



The Bulletin, pubhcation of which was begun in 1875, is a series 

 of more elaborate papers, issued separately, and, like the Proceedings, 

 based chiefly on the collections of the National Museum. 



A quarto form of the Bulletin, known as the "Special Bulletin," has 

 been adopted in a few instances in which a larger page was deemed 

 indispensable. 



Since 1902 the volumes of the series known as "Contributions from 

 the National Herbarium," and containing papers relating to the 

 botanical collections of the Museum, have been published as Bulletins. 



Richard Rathbun, 

 Assistant Secretary, Smithsonian Institution, in 



charge of the United States National Museum. 



March 12, 1917. ^ 



