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 

 4 < Smithsonian Contributions to Knowledge." The quarto series in- 

 cludes memoirs, embracing the records of extended original investiga- 

 tions and researches, resulting in what are believed 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 materials 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 express request of the Institution, and at its expense. 



The assignment of a work to one or the other of the two series will 

 sometimes depend upon whether the required illustrations can be pre- 

 sented more conveniently in tlie quarto or the octavo form. 



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 combi- 

 nation into volumes. 



While due care is taken on the part of the Smithsonian Institution to 

 insure a proper standard of excellence in its publications, it will be 

 readily understood that it cannot hold itself responsible for the facts 

 and conclusions of the authors, as it is impossible in most cases to verify 

 their statements. 



S. F. BAIED, 



Secretary S. I. 



