MAMMALS OF THE MEXICAN BOUNDARY. 59 



ACACIA GREGGII Gray. 

 DEVILS CLAWS. 



A common tree of Arizona and southern California ; abundant 

 along- the JMoxican Border. The larger trees have the trunk a foot 

 in diameter and reach the height of 20 feet. At Pozo de Luis these 

 acacias were shedding their leaves in January. It is a species of 

 the Sonoran Zone. In southwestern Texas there is a shrub acacia 

 resembling ^Imrk greggii (Cat. No. 152?), July 1, 1893, Sierra Blanca, 

 Texas), but with smaller leaves." 



PROSOPIS ODORATA Torrey and Fremont. 

 TORNILLO; SCREW BEAN. 



A slender, graceful tree, bearing twisted pods and whitish spines; 

 abundant along streams of the Lower Sonoran zone from tlie liio 

 Grande of Texas to the Coast Range Mountains of California. It is 

 usually of the size of the devils claws {Acacia areggi'i), though some- 

 times rivaling the mesquite. Along the Colorado River, in the 

 vicinity of Fort Mohave, Arizona, the forests of screw beans are 

 utilized by the Mohave Indians, who use the fruit for food. Heaps 

 of screw beans may be seen in all of their settlements. 



PROSOPIS GLANDULOSA Torrey. 

 MESatJITE. 



This is a common tree or shrub, as the case may be, from the Gulf 

 coast of Texas to the Pacific Ocean, though it is rare west of the Coast 

 Range Mountains, along the Mexican Boundary Line. The vertical 

 range of the mesquite is from sea level (near Monument No. 258), 

 and below it (in parts of the Colorado Desert) up to the lower timber 

 line (altitude 1,092 meters, or 5,550 feet, near Langs Ranch) on the 

 mountains of the interior. This is an exceedingly variable species. 

 In Texas it grows as a small tree, having a drooping habit, and fern- 

 like, long pinnate leaves. In the deserts of New Mexico, Arizona, 

 and California it becomes a shrub, forming mounds or sand hills in 

 the most fertile places. Along the Colorado River and its tribu- 

 taries it becomes a tree of considerable size. Along the Santa Cruz 

 River, in Sonora, are forests of unusually large mesquites, some of 

 which measure 2^ feet in diameter and 50 feet in height. The mes- 

 quites of the Colorado River bottom, below Fort Mojave, also have 

 distinct trunks and grow to an unusual height. 



a Another acacia (Acacia constrict a P>entham), usually considered as a shrub, 

 becomes a small tree on the headwaters of the Yaqui River, near the Inter- 

 national Line and the boundary between New Mexico and Arizona. 



