INTRODUCTION. XVII 



Potts, Major Rich, and Lieut. Couch. Incidental mention of these ig also made occasionally in 

 the present volume, wherever necessary to complete the indications of geographical distribu 

 tion. 



The collections of all the government parties just mentioned were transmitted, from time to 

 time, to the Smithsonian Institution, and were there properly cared for until the return of the 

 several expeditions. They were then placed in the hands of the naturalists selected to elabo 

 rate them, and the necessary drawings prepared, within its walls, under the direction of the 

 Institution, to which, also, was committed the general supervision of the engraving and 

 printing of the plates. Every facility has been furnished by the War Department, through 

 Captain Humphreys, in charge of the Pacific Railroad Office, and the heads of the different 

 expeditions, for bringing the results properly before the world. 



