

ADVERTISEMENT. 



The present series, entitled " Smithsonian Miscellaneous Collections," 

 is intended to embrace all the publications issued directly by the Smith- 

 sonian Institution in octavo form ; those in quarto constituting the 

 " Smithsonian Contributions to Knowledge." The quarto series include 

 memoirs, embracing the records of extended original investigations and 

 researches, resulting in what are believed to be new truths, and constitut- 

 ing 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 materials for research ; lists and synopses of species of the 

 organic and inorganic world ; museum catalogues ; reports of explora- 

 tions ; aids to bibliographical investigations, etc., generally prepared at the 

 express 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. 



