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 constitut- 

 ing tlie "Smithsonian Contributions to Knowledge." The quarto 

 series includes memoirs, emliracing the records of extended original 

 investigations and researches, resulting in what are believed to be new 

 truths, and constituting positive additions to the sum of human knowl- 

 edge. 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; reports of 

 explorations; aids to bibliographical investigations, etc., generally pre- 

 pared at Ihe 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. 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 pub- 

 lished aiid largely distribnlod, years 1)efore their combination into 

 volumes. 



CHAS. D. WALCOTT, 

 Secretary of the Smithsonian Institution, 



(iii) 



