PLATE 7 



Fig. 8. The salt-bush association, on second-bottom above the reach of 

 the highest overflow. The large plant in the center of the picture is the 

 creosote bush (Larrea divarxcata) which in places invades the second bottom 

 nearly or quite to the edge of the mesquite and grows to larger size in such 

 places than on the desert mesa. The prevailing low, light-colored shrub, is 

 the salt-bush (Atriplex polycarpa). Winter visiting birds of this association 

 were: Nevada sage sparrow, Brewer sparrow and desert Bewick wren; mammals 

 caught at this point were Dipodomys merriami and Perognathus penicillatus. 

 Photograph taken one mile above Mellen, Arizona, February 27, 1910. 



Fig. 9. Tj-pical wash association, the catclaw {Acacia gregyii) being the 

 plant most constantly present. Thickets of catclaw are to be seen in the right 

 foreground, while large ironwood and palo verde trees are to be seen in the 

 middle distance. The distant hill slopes are dotted with creosote bushes, while 

 Atriplex polycarpa margins the wash in the immediate foreground. Eesident 

 birds of this wash association were: verdin, plumbeous gnatcatcher, and cactus 

 wren. Photograph taken March 10, 1910, on California side, near lower end 

 of Chemehuevis Valley. 



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