XIX. 



Fig. 1 . A low mound of sand held in place by Rhus aromalica. Several other 3peeies grow in the pro- 

 tected sand on its lee side. The small plants in the left foreground are Commelina virjfinica 



Fig. 2. A dense thicket of the sand-binder R/ius aromatica. The tumbleweeds, Cpclotoma atrtpHctfoHum, 



are the only plants on the blow-sand in front. -Upon the Bhlta are BlephorUta rhoU and its 



larvae, Peritius circumcinclus and its nymphs, Hestkt um tnattioa, 



and the predaccous Zelvssoctus. 



