ADVERTISEMENT. 



The extension of the scope of the National Museum during the past 

 few years, and the activity of the collectors employed in its interest, 

 have caused a great increase in the amount of material in its possession. 

 Many of the objects gathered are of a novel and important character, 

 and serve to throw a new light upon the study of nature and of man. 



The importance to science of prompt publication of descriptions of 

 this material led to the establishment, in 1878, of the present series of 

 publications, entitled "Proceedings of the United States National 

 Museum,^ the distinguishing peculiarity of which is that the articles 

 are published in signatures as soon as matter sufficient to fill sixteen 

 pages has been obtained and printed. The date of publication being 

 plainly expressed in each signature, the ready settlement of questions 

 of priority is assured. 



The articles in this series consist : First, of papers prepared by the 

 scientific corps of the National Museum ; secondly, of papers by others, 

 founded upon the collections in the National Museum ; and, finally, of 

 interesting facts and memoranda from the correspondence of the Smith- 

 sonian Institution. 



The Bulletins of the National Museum, the publication of which was 

 commenced in 1875, consist of elaborate papers (monographs of families 

 of animals, &c.), while the present series contemplates the prompt pub- 

 lication of freshly acquired facts relating to biology, anthropology, and 

 geology; descriptions of restricted groups of animals and plants; the 

 settlement of particular questions relative to the synonymy of species, 

 and the diaries of minor expeditions. 



The Bulletins and Proceedings are published by the authority and at 

 the expense of the Interior Department, and under the direction of the 

 Smithsonian Institution. 



The present volume, constituting the seventh of the series, has been 

 prepared under the editorial supervision of Dr. Tarleton H. Bean, 

 curator of the department of fishes. 



SPENCER F. BAIRD, 

 Director of the U. S. National Museum. 



United States National Museum, 



Washington, April 29, 1885. 



(n) 



