Horizontal and vertical extensions of root-systems of Carnegiea gigantea, Covillea 

 tridentata, and Parkinsonia microphylla, from the bajada west of West Wash, 

 Dec-ember, 1906. The Carnegiea is represented l.>y black, the Covillea b}' yellow, and 

 the Parkinsonia by green. 



