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 m 1878, are 

 intended primarily as a medium for the publication of original, and 

 usually brief, papers based on the collections of the National Museum, 

 presentincr newly acquired facts in zoology, geology, and anthro- 

 pology, 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 different subjects, as soon as printed. 

 The dates of publication are recorded in the tables of contents of the 



volumes. . . „ 



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

 series of separate publications comprising chiefly monographs ot 

 laro-e 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. ihe majority 

 of the volumes^re octavos, but a quarto size has been adopted m 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 Contribu- 

 tions from the National Herbarium, has been published as bulletins. 

 The present work forms No. Ill, of the Bulletin series. 



William deC. Ravenel, 

 Administrative Assistant to the Secretary, 

 in charge of the United States National Museum. 

 Washinoton. D. C, June 20, 1920. ^^^ 



