ADVERTISEMENT 



The scientific publications of the National Museum include two series, 

 known, respectively, as Proceedings and Bulletin. 



The Proceedings series, 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 dis- 

 tributed as published to libraries and scientific organizations and to 

 specialists and otliers interested in the different subjects. The dates at 

 which these separate papers are published are recorded in the table of 

 contents of each of the volumes. 



The series of Bulletins, the first of which was issued in 1875, contains 

 separate publications comprising monographs of large zoological groups 

 and other general systematic treatises (occasionally in several volumes ), 

 faunal works, reports of expeditions, catalogs 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 

 Bulletin series appear volumes under the heading Contributions 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. 191 of the Bulletin series. 



Alexander Wetmore, 

 Secretary, Smithsonian Institution. 



