XX. 



Fig. 1. Populus Dilatata spreading by suckers over the blow sand into the blowout. 

 Jamesii grows in abundance in the right foreground. — Upon the Popvius 

 are Metachroma parallelum and 71/ . angustulum. 



Cri&tatella 



Flo. 2. A dune has invaded a walnut grove. The ground cover on the moist shaded sand 18 mainly 



Solarium nigrum and Sicyos angulatus. — Under logs are Ischnoptera inceyualis, 



Udeopsylla robusta, Pangitus, etc. 



