BOTANICAL GEOGRAPHY. 461 



common with other Halophytes belonging to the same botanical group. The 

 other most common thickets of the upper steppe consist of Maeagnns 

 argentea and Shepherdia argentea ; then Amorpha frutescens, Rosa parvifolia, 

 and woody Synantheracese, e. g. Iva and Bigelovia. Juniperus andina (J. repens 

 of Wied), with Yucca angustifolia, appear to be confined to the Missouri 

 country below the mouth of the Yellowstone river. Geyer's further distinc- 

 tions of several districts of vegetation in the region of the upper terraces 

 has not been carried out sufficiently clearly. The following may be regarded 

 as characteristic forms : Of the Leguminosse, Astragalus, Homolobus, 

 Psoralea, Glycyrrhiza, Hosackia, Schrankia, and Amorpha; Cruciferee, Stan- 

 ley a pinnatifida ; Loasese, Bartonia ornata ; Onagraria?, (Enothera ; Cacteee, 

 Opuntia missurica ; Umbelliferse, Cymopterns ; Synantheraceae, in addition 

 to the above-mentioned shrubs, several Chrysopsidese, Cichoracese, Achillea ; 

 Scrophulariaceae, the same genera as those of the lower terraces ; Chenopo- 

 diacece, in addition to Sarcobatus: KocMa, Salsola, Chenopodium, and Atriplex; 

 Liliaceee, CalocJiortus and Allinm, Iris, Triglochin maritimum, Carex ; Gra- 

 minacese, e. g. Triticum missuricum, B ordeum jubatum, and Ceratochloa. 



Geyer's description is rendered geographically more clear by the excellent 

 diary kept by FREMONT of his travels, who, being the chief of an expedition 

 of discovery, and furnished with botanical knowledge, explored the whole of 

 the steppes of the North American prairies, down to Lower Oregon and 

 Upper California, in different directions, with the most fortunate results 

 (Narrative of the Exploring Expedition to the Rocky Mountains in 1842, and 

 to Oregon and North California in 1843-44. Washington, 1845. I am only 

 acquainted with it from the English edition, London, 1846-8). On this side 

 of the Rocky Mountains, Eremont followed the same course to the River 

 Platte as Geyer ; on the second occasion, he ascended the Kanza and its 

 accessory streams, to the central chain. The country ascends very gradually 

 from the bifurcation of the Kanza (79 W. long.), to the foot of the Rocky 

 Mountains, and on the west side of the mountain the land sinks to the con- 

 flux of the Lewis and Oregon, as is evident from the following line of level 

 which was determined barometrically by Eremont, and intersects the entire 

 steppe from east to west. Bifurcation of the Kanza (79 W. long.) = 926'; 

 3iver Platte (81) = 200(y; River Platte (83) ==2700'; Eort Laramie, on 

 the Platte (87) = 4470'; and almost in the same meridian, Eort Trains 

 (40 16' N. lat.) == 4930'; as also the River Arkansas (38 15' N. lat.) 

 = 4880'; Artemisia-steppe, at the eastern foot of the Rocky Mountains 

 (41 36' N. lat. and 90 W. long.) = 6820'; south pass through the Rocky 

 Mountains, in a deep depression, which does not possess any mountain cha- 

 racter (42 27') = 749CK; foot of the Rocky Mountains, at the upper part 

 of the course of the Colorado of California (41 46') = 6230'; Eort Hall, 

 on the Lewis (43 N. lat., 95 W. long.) = 4500'; River Lewis (43 49' 

 and 99) 2100'; River Lewis (44 17' and 100 W. long.) = 1880'. 



