ADVERTISEMENT, 



The present series, entitled " Smithsonian Miscellaneous Col- 

 lections," 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 believed 

 to be new truths, and constituting positive additions to the sum of 

 human knowledge. The octavo series is designed to contain re- 

 ports on the present state of our knowledge of particular branches 

 of science: instructions for collecting and digesting facts and ma- 

 terials 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 

 expressed request of the Institution, and at its expense. 



The position of a work in one or the other of the two series 

 will sometimes depend upon whether the required illustrations can 

 be presented more conveniently in the quarto or the octavo form. 



In the Smithsonian Conti'ibutions 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 

 niany cases, works have been published, and largely distributed, 

 years before their combination into volumes. 



While due care is taken on the part of the Smithsonian Institu- 

 tion 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 im])0ssible in most 

 cases to verify their statements. 



SPENCER F. BAIRD, 



Secretary S. I. 



( vii ) 



