Ipostelsia 71 



acteristic rocky back beach is found only along 

 one end of the lake. At the rate which this 

 body of water is filling in, it is only a question 

 of time when the three zones shall have been 

 pushed so far out that what is now the back 

 beach zone shall have yielded its place to the 

 invading forest. The present tenants of the 

 rocky ledges may be able to maintain their foot- 

 hold even after the forest has become estab- 

 lished in front, yet new conditions of light and 

 illumination will eventually tend to bring about 

 a change. The plants dwelling upon this type 

 of rocky beach constitute a Rosaceous shrub 

 society, of which the principal species are: 

 Spiraea mcnzicsii Riihus spectabilis 



Rub us pari'ijiorus NeiUla capitata 



Together with these occur Vaccinium par- 

 vijoliiim and a few herbaceous forms like Po/y- 

 stichiim munitum, Adiautum pedatum, etc. 



In the non-rocky back beach, there are re- 

 gions which correspond to those of the mid and 

 front beaches with reference to elevation and 

 soil composition. Along the sandier, elevated 

 portion the composition is slightly more diver- 



