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 collec- 

 tions 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 organiza- 

 tions 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 series of Bulletins^ the first of which was issued in 1875, con- 

 tains separate publications comprising monographs of large zoologi- 

 cal 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 Contributiotis 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. 183 of the Bulletin series. 



Alexander Wetmorb, 

 Assistant Secretary^ Smithsonian Institution. 

 II 



