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; and 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 prepared at the 

 express request of the Institution. 



The " Smithsonian Contributions to Knowledge," in quarto form, 

 embraces 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. 



In both of these series each article bears a distinct number, and is 

 also separately paged unless the entire volume relates to one subject. 

 The 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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