//^.6^' 



ADVERTISEMENT 



The Smithsonian Miscellaneous Collections series contains, since the 

 suspension in 1916 of the Smithsonian Contributions to Knowledge, 

 all the publications issued directly by the Institution except the An- 

 nual Report and occasional publications of a special nature. As the 

 name of the series implies, its scope is not limited, and the volumes 

 thus far issued relate to nearly every branch of science. Papers in 

 the fields of biology, geology, anthropology, and astrophysics have 

 predominated. 



Leonard Carmichael, 

 Secretary, Smithsonian Institution. 



(iii) 



