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 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 in- 

 organic 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 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 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. 



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 impossible in most 



cases to verify their statements. 



Spencer F. Baird, 

 Secretary Smithsonian Institution. 



vn 



