ADVERTISEMENT. 



The scientific publications of the United States National Museum consists of two 

 series, the Proceedings anti the BuUetins. 



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

 marily 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 

 zoologj', geology, and anthropology, 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 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 (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. 110 of the Bidletin series. 



William deC. Ravenel, 

 Administrative Assistant to the Secretary, 

 In charge of the United States National Museum. 



Washington, D. C, June 20, 1920. 



