366 Annals of the Carnegie Museum. 



be said along this line in the discussion of the phyto-geographical re- 

 lations of the flora of Presque Isle. 



Outside of the Fragaria-PolytricJmm formation, and advancing 

 gradually into that zone, is the Rhus-Almis formation, which is quite 

 well developed, and around the outer border is even 'passing into a 

 forest-formation, as indicated by the invading Primus serotina and 

 Acer saccharinum. 



Stage H. — Cranberry Pond. 



In the various lagoons or ponds to the south and west of Long Ridge 

 there can be more or less clearly traced a gradual development into 

 ecological conditions and vegetational formations quite dissimilar to 

 those described for the lagoons to the north and west of the ridge. 



The habitat most typical of what perhaps can be most definitely 

 designated as the next clearly distinct stage after Stage G, is Cran- 

 berry Pond, a long narrow lagoon closely similar to Ridge Pond and 

 comparatively but little older. The lagoon has practically the same 

 water-level as Lake Erie, there being, however, no drainage out- 

 let excepting through f-eepage, a character common to most of the 

 lagoons of the peninsula. Currents are thus reduced to a minimum, 

 there being no drainage currents, and the action of the wind upon the 

 surface of the lagoon is also very small, owing to the narrowness of 

 the basin and the protection afforded by the tall forest closely sur- 

 rounding it. 



The vegetational formations, proceeding from the middle of the 

 pond to the shore, are as follows : 



(</) Potamogetoii Formation, 



i^b') Castalia-Nymphcea Formation, 



(<;) Cephalanthus-Cornus Formation, 



(^ ) Sphagnum- Oxy coccus Formation, 



(<?) Aronia-Polyirichmn Formation, 



(/) Rhus-Alnus Formation, 



(<§') Prunus-AccrYoxm2X\ow. 



The Poiavwgetoti Formation. 



With the limited means at hand the writer was unable to make more 

 than a very superficial survey of the deeper waters of the pond, but 

 enough was learned to make it certain that there is more or less Chara 

 and Naias in the central portion of the pond, and it is quite likely that 



