50 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



of this tree arc scarce on the San Luis Mountains; and few were 

 seen that reached 25 feet in height on the San .lose Mountains; but 

 large trees were frequently seen in the Iluachuca Mountains. (Plate 

 V,fig.2.) 



Its vertical range on the San Luis Mountains is from -2.-204: meters 

 ( 7. 230 feet) to the summit, or 2,400 meters (7,874 feet) ; on the San 

 Jose Mountains, from 2,085 meters (6,840 feet) to the summit (2,541 

 meters, or 8,337 feet) ; and on the Iluachuca Mountains, from 2,133 

 meters (7,000 feet) to the summit (2,887 meters, or 9,472 feet). 

 The two largest specimens seen on the San Jose Mountains measured, 

 respectively, 21 feet in diameter and 30 feet in height (altitude 7,150 

 feet), and 2 by GO feet (altitude 7,250 feet; beside a spring). 



QUERCUS BREVILOBA (Torrey) Sargent. 

 DURAND OAK. 



This is a large evergreen oak. abundant along- the streams of 

 Texas as far west as Devils River. It usually leans toward the 

 streams along which it grows, the branches frequently touching those 

 of the opposite side. In Texas this species is the analogue of Quer- 

 cus (/(//■/folic in California. 



QUERCUS UNDULATA Torrey. 

 ROCKY MOUNTAIN OAK. 



This is a scrub oak, ranging from western Texas to Arizona. It is 

 less abundant on the Mexican Boundary than farther north. 



QUERCUS ENGELMANNI Greene. 

 ENGELMANN OAK; EVERGREEN WHITE OAK. 



This is a tree of the Upper Sonoran zone, west of the Coast Range, 

 in California and Lower California. This zone was crossed between 

 Campo and Tecate Mountain (Monuments Nos. 240 to 245), on the 

 Mexican Line. Farther north, between San Diego and Cuyamaca 

 Mountain, it forms a somewhat broader zone, below the range of 

 Pinus sdbiniana. It is a handsome evergreen oak of medium size. 



QUERCUS OBLONGIFOLIA Torrey. 

 OBLONGLEAF OAK; BLUE OAK. 



This is the oak of the lower timber line on the mountains of the 

 interior region, where the groves of this tree bear a general resem- 

 blance to apple orchards in the East. The leaves are small, glaucous, 

 and evergreen. We found it on the Dog Mountains, in Guadalupe 

 Canyon, and on the Mule, San Jose, Iluachuca. Patagonia, and 

 Pajaritos mountains, always forming a narrow belt at the lower 

 general timber line. Its vertical range is from 1,266 meters, or 4,157 

 feet (Monument No. 73, in Guadalupe Canyon), to 1,874 meters, or 



