ADVEETISEMENT 



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 scien- 

 tific organizations and to specialists and others 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, 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 volimies 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 

 Hcrharium.! in octavo form, published by the National Museum since 

 1902, which contain papers relating to the botanical collections of 

 the Musemn. 



The present work forms No. 174 of the Bulletin series. 



Alexander Wetriore, 

 Assistant Secretary^ Smithsonian Institution. 



Washington, D. C, March 22, 1939. 



