204 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. [Vol. YI. 



cnpy the low bank on the opposite side. The country receding from 

 either shore is covered to some extent by generally worthless shrubbery, 

 though northward the valley widens in several places and presents a 

 pleasing landscai)e. 



Further information regarding the reports of the authorities cited, in 

 addition to others relating to the birds of the region under consideration, 

 will be found by reference to the Api)endix. 



W. J. HOFFMAK, M. D. 



Washington, D. C, February^ 1881. 



EEMAEKS O:^ THE DISTEIBUTIOis^ OF VEGETATION IK NE- 

 VADA AS AFFECTING THAT OF THE AVIFAUNA. 



There is probably no other area of like extent within'the confines of 

 the United States that presents a greater variety of physical features 

 than Nevada ; and as the distribution of birds is closely correlated with 

 that of the vegetation, it becomes a matter of propriety as well as of in- 

 terest to refer to the subject more fully than would under ordinary cir- 

 cumstances be necessary. Extending from latitude 35° to 42° north, 

 and from longitude 114° to 120° west, this region embraces about 112,000 

 square miles of surface, presenting nearly every variety of geologic con- 

 figuration and condition of soil, from the fertile and cultivated valley to 

 the parched and arid desert, exhibiting also extreme forms of vegeta- 

 tion, from the lichens of the zone of perpetual snow to the sub-tropic va- 

 rieties of Cactacece, &c. 



The average altitude of Nevada is about 5,600 feet. The greatest de- 

 pression — which receives all the drainage of the northern half of the 

 State — is located in the western portion, while toward the east there is 

 a gentle rise in elevation, as well as southward, until at a point between 

 Mount Nagle and Mount Magruder, when the descent toward the Colo- 

 rado Eiver and the Mojave Desert becomes more rapid. Throughout 

 the northern portion the water-courses are more numerous, furnishing 

 an abundant flora, while in the southern half of the State there exist 

 immense areas which are nearly, if not totally, destitute of vegetation, 

 with scarcely any indications of moisture save an occasional spring of 

 brackish or saline water; here also we find the ridges and mountain 

 peaks with scarcely any arboreal growth, unless their summits penetrate 

 the zone of Coniferce. 



In a previous paper* on the distribution of vegetation in portions of 

 Nevada, &c., the flora was divided into four distinct classes, viz : I, the 

 flora of the mountains ; II, the flora of the foot-hills ; III, the flora of 

 the plains ; and IV, the flora of the salt marshes. T-o these may be added 

 the aquatic, as well as other subdivisions of which further notice will 



*Am. Nat. x, 1877, pp. 336-343. 



