84 



BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



The following is a list of the arborescent flora : 



Populus fremontii Watson. 

 Querous undulata Torrey. 

 KcBberlinia spinosa Zuccarini. 

 Sapindus marginatus Willdenow. 



Juniperus monosperma (Engelmann) 



Sargent. 

 Yucca constriota Buckley. 

 Salix nigra Marshall. 

 Populus angustifolia James. 



The mistletoe {Phoradendron holleanum Eichler) grows abun- 

 dantly on the one-seed juniper. Other conspicuous plants are the 

 following : 



Ephedra trifurca Torrey. 



Phragmites phragmites (Linnaeus) 



Karsten. 

 Yucca haccata Torrey. 

 Yucca glauca Nuttall. 

 Dasylirion sp. 

 Agave palmeri Engelmann. 

 Berheris trifoUolata Moricand. 

 Astragalus nuttalUanus trichocarpus 



Torrey and Gray. 

 Parosela formosa (Torrey) Vail. 



Parosela pogonathera (Gray) Vai). 

 Fouqnieria splendens Engelmann. 

 Thamnosma texana Torrey. 

 Rh^s microphvlla Engelmann. 

 Opuntia arborescens Engelmann. 

 Cereus roemeri Muhlenpfort. 

 Cucurbit a fatidissima Humboldt, Bon- 



pland, and Kunth. 

 Senecio fllifoUus Nuttall. 

 Perezia nana Gray. 



Station No. 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 Eio 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 only trees were a few r^d junipers. Vegetation was, however, 

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

 valley, 4 miles (6 kilometers) wfest of Monument 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 

 Qf 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 



