ADVERTISEMENT. 



The scientific publications of ihc United States National Museum consist of 

 two series, the Proceedings and the Bulletins. 



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

 primarily as a medium for the publication of original, and usually brief, papers 

 based on the collections of the National Museum, presenting newly-acquired facts 

 in zoology, geology, and anthropology, including descriptions of new forms of 

 animals, and revisions of limited groups. One or two volumes are issued annually 

 and distributed to libraries and scientific organizations. A limited number of 

 copies of each paper, in pamphlet form, is distributed to specialists and others 

 interested in the different subjects as soon as printed. The date of publication is 

 printed on each paper, and these dates are also recorded in the tables of contents 

 of the volume. 



The Bulletins, the first of which was issued in 1875, consist of a series of sepa- 

 rate pubhcations comprising chiefly monographs of large zoological groups and other 

 general systematic treatises (occasionally in several volumes), faunal works, reports 

 of expeditions, and catalogues of type-specimens, special collections, etc. The 

 majority of the volumes are octavos, but a quarto size has been adopted in a few 

 instances in which large plates were regarded as indispensable. 



Since 1902 a series of octavo volumes containing papers relating to the botanical 

 collections of the Museum, and known as the Contributions from the National Her- 

 barium, has been published as bulletins. 



The present work forms No. 73 of the Bulletin series. 



RiCHAED RaTHBUN, 



Assistant Secretary, Smithsonian Institution, 

 In charge of the United States National Museum. 

 Washington, D. C, June 1, 1910. 



