ADYEETISEMENT. 



This work is the twenty-first of a series of papers intended to illnstrate 

 the collections of natural history and ethnology belonging- to the 

 United States, and constituting the i^ational Museum, of which the 

 Smithsonian Institution was placed in charge by the act of Congress of 

 August 10, 1846. 



It has been prepared at the request of the Smithsonian Institution, 

 and printed by authority of the honorable Secretary of the Interior. 



SPEXCER F. BAIRD, 

 Secretary of the Snuthsonian Institution. 

 Smithsonian Institution, 



Washington, March 29, 1880. 



