1902.] NATURAL SCIENCES OF PHILADELPHIA. 645 



supports, as shown ia fig. 1, three character plants, viz., Myrica 

 cerifera L:, Solidago semp^rvirens L. and Hadsonia tomnitosa 

 Nutt. The sides of the irregular basin not wind-swept support the 

 marram grass, Ammophila arenaria (L.) Link, Solidago semper- 

 virevs L., H adsonia tomentosa Nutt., and an occasional clump of 

 wax-berry, Myrica cerifera L. If the sand is still farther trans- 

 ported by the wind, there remain hillocks of dry sand in the center 

 of a level damp stretch on the level of the ground water. Some- 

 times the bottom of the hollow forms a level trough of wet sand, 

 surrounded by sun-dried sand on all sides. Such a hollow, illus- 



Fig. 2. 

 u. Solidago sempervirens L. ; v. Scirpus deUlis Pursh ; x. Panicum 

 virgaium L. ; t. Pure sand. 



traled in the accompanying figure (fig. 2), is tenanted by three 

 character plants. The wet sand supports a continuous growth of 

 8drpm debilis L. ; the side of the dune trough, Panicum virgatum 

 L., a grass which may be called a tussock grass, because it 

 does not form a continuous turf, but grows in clumps more or less 

 isolated from each other. In the higher drier sand of the depres- 

 sion, before the slopes of the dunes of the dune complex are 

 reached, there grows a character plant, Solidago sempervirens L. 

 We have, therefore, a replacement of the original dune occupants, 



