SMITHSONIAN 







lECTMS. 



VOL. XX. 



"bVKRT man is a valuable member of society who by his 0BSEUVATI0N8, RE8EAKCHES, 

 AND EXPEMMENTS PBOCUHES KNOWLEDGE FOR MEN." — 8MITHS0N. 



^^Tt^ 



L 



WASHINGTON: 



PUBLISHED BY THE SMITHSONIAN INSTITUTION. 



1881. 



