ADVERTISEMENT. 



The scientific publications of the United States National Museum 

 consist of two series — the Proceedings and the Bulletins. 



The scientific publications of the United States National Museum 

 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 annu- 

 ally and distributed to libraries and scientific organizations. A 

 limited number of copies of each paper, in pamphlet form, is distrib- 

 uted 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 

 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 work, 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 relat- 

 ing to the botanical collections of the Museum, and known as the 

 Contributions from the National Herbarium, has been published as 

 bulletins. 



The present work forms No. 92 of the Bulletin series. 



Richard Rathbun, 

 Assistant Secretary, Smithsonian Institution, 

 In charge of the United States National Museum. 



Washington, D. C, July 21, 1915. 



Ill 



