1(3 INTRODUCTORY LETTER. 



The expedition being divided, a collector was assigned to each of the 

 main parties, who diverged therefrom in the vicinity of the rendezvous 

 camps and other desirable points along the line of travel. In this way, 

 facility was also afforded for visiting portions of Nevada, California, and 

 Utah, which were minutely examined; special attention being paid to the 

 areas in basins of drainage of large parts of the several interior basins, as 

 Owens River, Death Valley, Amargosa Desert, Las Vegas Valley, valleys 

 of the Muddy and Eio Virgen, southeastern edges of the San Francisco 

 Plateau, Verde and Salt Rivers, and Rio Gila. The map of the region in 

 question, however, affords a more graphic as well as a better explanation of 

 the localities visited than would any written description. 



The reports on the parts of the collection which were received show 

 that the regions visited are possessed of great interest to the student of 

 natural history, and with the study of the specimens themselves can hardly 

 fail to extend greatly our knowledge of the range of the fauna and flora of 

 North xluierica. 



It is to be regretted that the great fire in Chicago left but few of the 

 specimens gathered; those that remain, however, suffice to attest the reputa- 

 tion for zeal and industry of the gentlemen by whom the collection was 

 made, and are abundant evidence to warrant the belief that the collection 

 entire must have been extremely interesting. 



Confident, perhaps, of the recent universally marked increase in atten- 

 tion to this branch of natural science, and of the great enthusiasm being 

 manifested by foreign governments in kindred researches, and, perchance, 

 not unmindful of the necessity for increased knowledge of our own fauna 

 and flora, for the proper study of the fauna and flora of other lands, and 

 that to tins end specimens were necessary for comparison to establish the 

 degrees of resemblance which exist between different bodies, in 1872 every 

 facility practicable Avas afforded. 



In 1872, the natural history branch of the survey was placed in my 

 charge, with Mr. II. W. Henshaw, as assistant. The expedition was organ- 

 ized at Salt Lake (Jit}', where investigations were made in regard to the 

 natural history of the vicinity of Great Salt Lake. 



From this point, Mr. Henshaw and myself proceeded south fifty milea 



