ADVERTISEMENT. 



The scientific publications of the 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 anthropol- 

 ogy, including descriptions of new forms of animals, and revisions of 

 limited groups. One or two volumes are issued annually and dis- 

 tributed 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 diflPerent 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 volumes. 



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

 series of separate publications comprising chiefly monographs of 

 large zoological groups and other general systematic treatises (occa- 

 sionally 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 Con- 

 tributions from the National Herbarium,, has been pubhshed as 

 bulletins. 



The present work forms No. 81 of the Bulletin series. 



Richard Rathbun, 

 Assistant Secretary, Smithsonian Institution, 



In charge of the United States National Museum. 



Washington, D. C, June 2, 1913. 



