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 be- 
lieved 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 mate- 
rials for research; lists and synopses of species of the organic and 
inorganic world ; museum catalogues; reports of explorations; aids 
to bibliographical investigations, ete., generally prepared at the ex- 
press 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 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 volunre in which it is placed. In many 
cases works have been published and largely distributed, years 
before their combination into volumes. 
S. P. LANGLEY, 
Secretary S. I, 
