INTRODUCTION. 
XVII 
Potts, Major Rich, and Lieut. Couch. Incidental mention of these is 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. 
