ADVERTISEMENT 



The scientific publications of the National Museum include two 

 series, known, respectively, as Proceedings and Bulletin. 



The Proceedings^ begun in 1878, is intended primarily as a medium 

 for the publication of original papers, based on the collections of 

 the National Museum, that set forth newly acquired facts in biology, 

 anthropology, and geology, with descriptions of new forms and 

 revisions of limited groups. Copies of each paper, in pamphlet 

 form, are distributed as published to libraries and scientific organi- 

 zations and to specialists and others interested in the different sub- 

 jects. The dates at which these separate papers are published are 

 recorded in the table of contents of each of the volumes. 



The Bulletin., the first of which was issued in 1875, consists of 

 a series of separate publications comprising monographs of large 

 zoological groups and other general systematic treatises (occasion- 

 ally in several volumes), faunal works, reports of expeditions, cata- 

 logues of type-specimens, special collections, and other material of 

 similar nature. The majority of the volumes are octavo in size, 

 but a quarto size has been adopted in a few instances in which large 

 plates were regarded as indispensable. In the BuUethi series appear 

 volumes under the heading Contnhutions from the United States 

 National Herbarium.^ in octavo form, published by the National 

 Museum since 1902, which contain papers relating to the botanical 

 collections of the Museum. 



The present work forms No. 138 of the Bulletin series. 



Alexander Wetmore, 

 Assistant Secretary, Smithsonian Institution. 



Washington, D. C, November 8, 1926. 



