382 Annals of the Carnegie Museum. 



This formation is somewhat intermediate in structure between the 

 corresponding formations of the ponds and lagoons of the peninsula 

 proper and the open marshes along the bay -side of the peninsula. The 

 pond originally must have been part of the bay, which with the forma- 

 tion of a bar across the narrow channel was cut off from the main 

 body of the bay, and was then filled in to a considerable extent by 

 vegetable remains and alluvial material from the mainland. 



Before the segregation of the pond from the bay it probably sup- 

 ported a littoral marsh, such as is now to be found along the shore to 

 the east, and the Carex-Phragmites formation is in part derived from 

 this former structure. 



The Salix-Aluus Formation. 



The Carex-Fhragmifes forniation is closely followed by a shrub- 

 formation, characterized by Salix and Alnus, as follows : 



Fades. — 



Salix fiigra, Abius incana. 



Second a j-y Species. — 



Eqidsetum hyemale, Cardamine pennsylvanica, 



Mentha canadensis, Fanicularia nervata, 



Galium aparine, Iinpatiens biflora, 



Cprniis stolonifera, Lycopus americanus, 



Sambucus canadensis, Lobelia syphilitica. 



This formation is but sparingly developed along the lakeward bank 

 of the pond, but it forms a considerable thicket at the lower end of the 

 pond around the outlet. The soil here is a black muck containing 

 more or less sand, the edaphic conditions of the habitat being quite 

 similar to those found along the average alluvial flood-plain in the 

 northern states. 



The Bay-Marsh-Thicket-Forest Succession. 



Along the bay shores of the peninsula there is a rather complex 

 series of formations, constituting what may be termed the Bay-Marsh- 

 Thicket-Forest Succession. The irregular contour of the peninsula 

 on the bay-side results in quite widely differing conditions at different 

 points due to the action of the surf and water-currents and the accumu- 

 lation of drift. The different environments thus brought about are 

 each characterized by correspondingly different vegetational structures, 

 which may be roughly classified as follows, upon the basis of habitat : 



