1902.1 



NATURAL SCIENCES OF PHILADELPHIA. 



647 



fringed directly with Ammophila arermria (L.) Link, Solidago 

 semp^rvirem L. and an occasional Mynca berry, while outside of 

 these the slopes of the dunes are wind-swept and destitute of 

 vegetation. In the degradation of a dune and the formation 

 of a wind-swept hollow, we have a succession of societies which are 

 approaching the ultimate state, that cf a mesophytic thicket. The 

 transition, 'noticed in the dune complex at Sea Side Park, is from 

 an intensely xerophytic association of species to marsh-dwelling 

 xerophytps, and from these in turn to xerophytic shrubs and trees 

 culminating in a mesophytic thicket filling the extent of the original 

 dune valley. 



The annexed figure (fig. 4) illustrates a xerophytic marsh associa- 



a o^yenrcvsmncTocarpus (Ait.) Pers. ; b. Vaccinium corymbosumL 



Raf o. que cL nnnor (Marsh) Sarg. ; p. Andropogon T^ro^n^cus L. ; 

 q. Kalnna I'u/nslifoha L. ; r. Chama'cypans thyoides (L.) B. b. F. , 

 8. Acer rubrum L. 

 tion in the transverse dune complex at Sea Side Park, surrounded 



