294 NORTH AMERICAN FAUNA. [No. 7. 



Walker Pass. — At the cast cud of Walker Pass it ascends to 1,050 

 meters (3,400 feet), and on the south slope of the hills on the north side 

 of the entrance to this pass reaches 60 meters (200 feet) higher, or to 

 1,100 meters (3,000 feet). 



Salt Wells Valley. — This valley is a true Larrea plain, and the Larrea 

 is continuous with that of the Mohave Desert. 



Panamint Valley. — Common on the gravel soils, reaching up on the 

 west slope of the Panamint Mountains as high as 1,500 meters (5,000 

 feet), and on favorable slopes to a still greater altitude. In Emigrant 

 Canon (which slopes to the northeast) it stops at about 1,200 meters 

 (4,000 feet). 



Death Valley. — Common throughout the gravel slopes on both sides 

 of the salt bottom, where it was just beginning to flower April 7. (It 

 was seen in flower in southern Arizona two weeks earlier.) It reaches 

 north through the lower part of the Northwest Arm of Death Valley 

 (Mesqnite Valley) as far as Grapevine Canon, keeping on the gravel 

 slopes, but does not occur much further north, the altitude being too 

 great. 



Owens Valley. — In Owens Valley, Larrea, is restricted to the extreme 

 southern end of the valley, except along the east side where it ranges 

 for some miles north of Owens Lake, along the warm west slope at the 

 foot of the Inyo Mountains, this being the hottest slope exposure of the 

 valley. South of Owens Lake it occurs in scattering patches for several 

 miles, and completely covers the broad valley between Haway Mead- 

 ows and Little Owens Lake, this valley being a true Larrea plain. 



NEVADA. 



Amargosa Desert. — At the point where the clay soil of Ash Meadows 

 changes to the gravel of the Amargosa Desert proper, Larrea begins 

 with a solid front and ranges northward without interruption over the 

 whole of the north arm of the Amargosa Desert, forming one of the 

 purest Larrea plains met with. Throughout the greater part of this 

 desert the Larrea is hardly invaded by any other plant except the 

 small and inconspicuous Chorizanthe rigida. The Larrea on this desert 

 is stunted, hardly averaging more than § of a meter (about 2 feet) in 

 height, and along the northern edge of the desert is mostly dead; per- 

 haps winter killed. It was heavy with its woolly fruit May 30, though 

 a few blossoms were seen here and there. At the same date it was 

 still in flower in Indian Spring Valley. 



Oasis Valley. — Most parts of Oasis Valley are a little too high for 

 Larrea, which forms a belt on favorable slopes hardly more than three 

 miles wide. On good south and southwest slopes a scattering growth 

 reaches as high as 1,370 meters (4,500 feet). To the east of the north 

 end of Oasis Valley is a small valley draining into the east fork of 

 Amargosa Creek in which a little Larrea occurs. It does not grow east 

 of the main part of Bare Mountains, or anywhere to the east or north 



