470 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM [18S5. 



The vegetation is that peculiar to the great Texano-Mexican Desert. 

 The sparse trees are confined to the alhivial bottom and dependent 

 ravines ; they are Cottonwood, Hackberry, Mesquite, Screw Bean and 

 Willow {Salix longifolia and nigra). Shrubs and bushes are common 

 enough, but in scattered thickets nowhere forming a dense chaparral ; 

 those preponderating on mesas and hills are : 



Acacia Greggii and constricta. 



Mimosa borealis and hiuncifera. 



Dalea formosa. 



Condalia ohovata and spathulata. 



Zizyphus obtusifolius. 



Kceberlinia spinosa. 



Celtis pallida. 



Lycium Carolinianum, Berlandieri, puberulum. 



Mozinna spathulata. 



Ephedra antisypMlitica and trifurca. 



Larrea Mexicana. 



Flourensia cernua. 



Yucca angustifolia. 

 The Palmo {Yucca baccata, var. australis), with tall caudex, 10 to 20 

 feet high and 1 to 2 feet in diameter, covers the broad graded incline 

 extending from the valley to the Chenate Mountains. The obnoxious 

 Lechuguilla {Agave heteracantha) is everywhere but too common. The 

 Bear-Grass or Sotol {Dasylirion Texanum) is also conspicuous. Of the 

 abundant Cacti the most remarkable species are: Anhelonia fissurata 

 (Pellote) bearing a beautiful flower and used medicinally by Mexicans ; 

 Anhelonia Williamsii not before observed on this side of the Rio Grande; 

 Cereus Greggii^ one of the most ornamental of its class ; Gereus stramineus 

 (Strawberry Cactus) with large, red, delicious fruit. 

 The bottom is covered with such weeds as — 



Nama hispidum. 



Solarium nigrum and elwagnifoUuni. 



Fortulaca oleracea, retusa, lanceolata. 



Petunia parvijlora. 



Sida hederacea. 



Gucurbita perennis. 



Lippia nodiflora. 



Tribulus maximus. 



Bumex Berlandieri. 

 And also the following Composites : 



Helianthus lenticularis and ciliaris. 



Verbesina encelioides. 



Aster spinosus, tanacetifolius and canescms. 



Coreopsis cardaminefolia. 



Aplopappus spinulosus. 



Gutierrezia Terana. 



Selenium amphibolum. 



