84 



BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



The followincr is a list of the arborescent flora 



Jnniperus nioiiospernia (Eugelmaim) 



Sargent. 

 Yucca constricta Buckley. 

 Salix nigra Mai'shall. 

 Popiilus aiiffustifolia James. 



Populus fremontii Watson. 

 Quercus undulata Torrey. 

 Koeherlinia spinosa Zuccarini. 

 Sapindus iiiarf/iiiatus Willdenow. 



The mistletoe (Phoradendron holleanum Eichler) grows abun- 

 dantly on the one-seed junij^er. Other conspicuous plants are the 

 following : 



Porosela po(/o)i(it]icra (Gray) Vai). 

 Foitqiiicria fiplcndens Engelmann. 

 Thanniosiiia texana Torrey. 

 Rhus microphylla Engelmann. 

 Opuntiu arhorcscois Engelmann. 

 Cere us rfrnieri Miililenpfort. 

 Ciiritrhita faiidissijiia Humboldt, Bon- 



pland, and Kunth. 

 Se)iecio fiUfoliiis Nuttall. 

 Peres ia na»a Gray. 



Ephedra trifurca Torrey. 



Phragmites phragmltes (Liumeus) 



Karsteu. 

 Yucca haccata Torrey. 

 r»cca gJauca Nuttall. 

 Dasylirion sp. 

 Agave pahneri Engelmann. 

 Berber is trifoJioIata Moricand. 

 Astragalus nutfallianus trichocurpus 



Torrey and Gray. 

 Parosela formosa (Torrey) Vail. 



Station Xo. 11. — Upper Corner Monument (No. 40) at the west 

 end of the boundary parallel 31° 47'. At this point, 159 kilometers 

 < 99 miles) west of the Rio Grande, the Boundary Line bends at a 

 right angle and extends south 49.83 kilometers (30.96 miles) on the 

 meridian 108° 12' 30". Our camp was made beside Monument No. 

 40, in the midst of a tangle of hills known as the Apache Mountains, 

 the highest of which has an altitude of 1,656 meters (5,433 feet). 

 The onh' trees were a few red junipers. Vegetation was, however, 

 more luxuriant than in the region to the eastward. The lowest 

 valley, 4 miles (6 kilometers) west of JNlonument No. 40, has an 

 altitude of 1,350 meters (4,430 feet) ; like others of the vicinity, it 

 is covered with good grass. Our animals were kept at Mosquito 

 Springs, our men being supplied with water in metal water wagons 

 from wells at a distance. Collections in nearly all of the depart- 

 ments usually covered were made at this place from April 22 to May 

 15, 1892. The rock formation in the neighborhood of Monument 

 No. 40, in the Apache Mountains, is largely calcareous. Rising im- 

 mediately north of the Corner Monument is a series of rounded hills 

 of lime rock, in which the network of (mostly projecting) white 

 veins of silicious materials are very characteristic. In places most 

 of the rocks are covered with nodular projections, from differential 

 weathering, which make walking over them very wearing on shoe 

 leather. There has been an overflowing of lava, and fragments of 

 vitreous obsidian are scattered freely about the region. Southwest 

 from Monument No. 40 lie the Sierra Rica of Chihuahua, the base of 



