304 The Ohio Naturalist. [Vol. VIII, No. 6, 



or pond. On Cedar Point, however, the elevation of the habitat 

 of the various zones due to the accumulation of vegetable matter 

 muse to some degree be counteracted by the general rise of the 

 water table consequent to the cumulative rise of water in Lake 

 Erie, — 2.14 feet per century. Ti; seem.s likely that, in some cases 

 at least, the general movement may be reversed as to the con- 

 centric vegetational formations, so that they may move away 

 from the central portion of the depression; thus, from habitats 

 more hydrophytic to less hydrophytic ones. 



■At the northeast corner of Cedar Point sand is rapidly accum- 

 ulating along the shore to the south of the Jetty Protection or 

 Breakwater and a lagoon is now (1907) being segregated from the 

 Lake near the old light-house building. There is at this place a 

 considerable indrifting of organic drift debris of various sorts so 

 that the vegetation shows somewhat more of an affinity to that 

 of a humus marsh or pond than is usual in beach lagoons. The 

 initial stage here appears from the studies given it (1905-7) to 

 be essentially as follows: 



Stage A. 



a. Potamogeton Formation. 



b. Populus-Salix Formation. 



The Potamogeton Formation. 

 Facies: Potamogeton pectinatus . 

 Secondary Species: 



Vallisneria spiralis, Potamogeton natans, etc. 



The Popnhis-Salix Formation. 

 Facies: Populus deltoides, 



Salix cofdata. 

 Secondary Species: 



SaHx fragtlis ('), Salix lucida, 



Cakile edentula, Strophostyles helvola, 



Xanthimn commune. 



This latter formation may be considered as identical with the 

 beginning of a Populus-Salix Ridge Formation but, under the 

 conditions leading to the development of a sand ridge, the 

 willows soon disappear while, under the more uniform condi- 

 tions leading through the different stages of a lagoon succession, 

 the willows are relatively quite important. 



In the lagoon succession at Presque Isle the second stage 

 shows the following structure, this appearing to be typical also 

 for the Cedar Point succession, although somewhat mixed in the 

 lagoon under discussion: 



Stage B. 



a. The Potamogeton Formation. 



b. The Juncus-Eleocharis Formation. 



c. The Populus-Salix Formation. 



