ADVERTISEMENT. 



The present series, entitled "Smithsonian Miscellaneous Collec- 

 tions," is intended to embrace all the publications issued directly 

 by the Smithsonian Institution in octavo form ; those in quarto 

 constituting the "Smithsonian Contributions to Knowledge." The 

 quarto series includes memoirs, embracing the records of extended 

 original investigations and researches, resulting in what are be- 

 lieved to be new truths, and constituting positive additions to the 

 sum of human knowledge. The octavo series is designed to contain 

 reports on the present state of our knowledge of particular branches 

 of science ; instructions for collecting and digesting facts and mate- 

 rials for research ; lists and synopses of species of the organic and 

 inorganic world ; museum catalogues ; reports of explorations ; aids 

 to bibliographical investigations, etc., generally prepared at the ex- 

 press request of the Institution, and at its expense. 



In the Smithsonian Contributions to Knowledge, as well as in 

 the present series, each article is separately paged and indexed, and 

 the actual date of its publication is that given on its special title 

 page, and not that of the volume in which it is placed In many 

 cases works have been published and largely distributed, years 

 before their combination into volumes. 



S. P. LANGLEY, 



Secretary S. I. 



[31 



