Q2. BOTANICAL FEATURES OF NORTH AMERICAN DESERTS. 
a tendency on the part of the native plants to develop marked storage 
capacity for water. The distribution of the scanty rainfall throughout 
the year in any region will favor the development of slowly growing 
xerophytic forms. 
METEOROLOGY. 
The principal features in the distribution and total amount of rainfall 
in several localities which may be included within the arid regions of 
North America are given below. The data concerning the maximum and 
minimum temperatures and rate of evaporation afford a means of esti- 
mating the actual usefulness or availability of water-supply for the native 
vegetation. Thus, for example, evaporation is so great and humidity of 
the air so small, in the southernmost stations given, that the effectiveness 
of the rainfall in meeting the needs of plants is diminished 50 or even 60 
percent. Of the localities named below, El Paso, Fort Wingate, Chihua- 
hua, and San Luis Potosi may be included in the Chihuahuan Desert, 
and the other places within the Nevada-Sonoran Desert. 
METEOROLOGICAL TABLE. 
The following tables give the mean rainfall and the absolute maxi- 
mum and minimum temperatures for 16 stations, 13 in the United States 
and 3in Mexico. All data for the United States stations are from records 
in the U. S. Weather Bureau. Data for two Mexican stations, San Luis 
Potosi and Chihuahua, are taken from the Monthly Bulletin of the Central 
Meteorological Bureau of Mexico for 1901. The rainfall record for Torres, 
Sonora, Mexico, was courteously furnished by Mr. T. Oldendorff, agent of 
the Sonora Railway at that point. The figures for this station were 
copied from the report made daily to the manager of the railway. 
