ADVERTISEMENT 



The present series, entitled " Smithsonian Miscellaneous Collec- 

 tions," is intended to embrace the principal 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 ex- 

 tended 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 ma- 

 terials for research ; lists and synopses of species of the organic and 

 inorganic world ; reports of explorations ; aids to bibliographical in- 

 vestigations, 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 bears a distinct number, and is also sep- 

 arately paged unless the entire volume relates to one subject. The 

 actual date of the publication of each article is that given on its 

 special title-page, and not that of the volume in which it is placed. 

 In many cases papers have been published and largely distributed, 

 several months before their combination into volumes. 



CHAS. D. WALCOTT, 

 Secretary of the Smithsonian Institution 



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