2 CO Scott on the Birda of Arizona. [April 



large and two smaller rivers, the Gila being- the former and the 

 Santa Cruz and San Pedro the two latter. 



Practically one mountain range, the Santa Catalina, forms the 

 backbone of this region. Rising abruptly to the northward and 

 eastward of Tucson, at a distance of from fifteen to twenty miles, 

 it extends in low hills to the Gila River, on the opposite side of 

 which, directly north, are the Mescal Mountains, which termi- 

 nate in the Pinal range. To the west of Tucson there are no 

 mountains proper in the area under discussion, but very consid- 

 erable hills break the great plain, and the Barboquivori Moun- 

 tains are reached at the extreme south-western border. On the 

 southern edge of the area is the vSanta Rita range, whicii is far 

 the most imposing in appearance, though in altitude its highest 

 peaks, as well as those of the Santa Catalinas, do not much ex- 

 ceed eleven thousand feet. Here much work has been done by 

 Mr. H. W. Henshaw, and also by Mr. F. Stephens. I mention 

 this to show the connection of the lists published by these gentle- 

 men with the remarks I shall have presently to offer. . 



The several points at which most of my material was obtained 

 are Tucson, Florence, Riverside, the San Pedro slope of the 

 Santa Catalinas, and the headwaters of Mineral Creek, which is 

 just outside of Pinal County, in Gila County. In addition, many 

 notes and items have been accumulated on rides and drives 

 between these various points, and now and again specimens 

 procured on such journeys, where anything of special interest 

 happened to occur. 



Let me now briefly describe the general environment of each 

 of the places above mentioned, in order to introduce to those of 

 my co-workers who have not been in this region some of the 

 more salient characteristics that obtain here. To make this more 

 clear and intelligible, a map is presented showing some of the 

 great physical features of the country, and to this constant refer- 

 ence will be made in the following pages. The map is based on 

 one compiled for the use of the General Land Otfice of the 

 United States, in 1S79, under J. A. Williamson, Commissioner. 



The region about Tucson, it will be noticed, is a great plain, 

 the altitude of which above the sea does not vary greatly from 

 3300 feet. During many months of the year this plain is arid, 

 but in the region watered by the Santa Cruz River, cultivation 

 by irrigation is largely pursued : and the same remarks apply to 



