364 Annals of the Carnegie Museum. 



(a) Nymphcea formation, which here consists mainly of Nyinphcea 

 advena with some Alisma Plantago and Pontederia cor data, together 

 with remnants of the Potamogeton formation — Potamogeion pectinatiis, 

 Naias flexilis, and some MyriophyUum spicatiim. 



(^b) The Scirpus-Typha formation, which is here represented by 

 Typha latifolia with some Scirpus americanus and Dulichium arundina- 

 ceum, and around the outer border a few plants of Carex gynandra. 



i^c') The Calamagrosis canadensis consocies of the Cladhwi-Cala- 

 magrostis formation with a few relict plants of Cladium. 



(^) The Rhus-Alnus formation, in which AInus has become mature 

 and dominant, having associated with it some Cornus amomum, Salix 

 discolor, and around the outside a secondary zone of Myrica. 



Another little pool near the south end of Long Ridge has about the 

 same vegetation, except that the Potamogeton formation is still intact in 

 a small patch. The structure is essentially thus : 



(a) Potamogeton formation, 



(^) Ny7np}icEa formation, 



(r) Typha-Scirpiis formation, represented only by the Typha lati- 

 folia consocies, and having around its outer border a distinct zone of 

 Carex gynandra. 



(d) The Rhus-Alnus formation, which has completely conquered 

 the Cladiutn- Calatnagrostis formation, and consists here mainly oiAlnus 

 incana and Cornus stolonifera. 



(e) There is the beginning in the older part of the shrub-zone of a 

 forest-formation, as is evidenced by the appearance of Acer sacchari- 

 num and Prunus serotina. 



At Lagoon B the following structure is evident : 



(«) Potamogeton Formation, 



(^b) Nymphcea Formation, 



(^) Scirpus-Typha Formation, 



(</) Cladium- Calamagrostis Formation, 



(<?) Fragaria-Polytrichum Formation, 



(/) Rhus-Alnus Formation, 



(^g) Prunus-Acer Formation. 



The above structure of vegetation is not exemplified in totality in 

 any one portion of the area characterized as Lagoon B. This is a 

 semi-marshy lagoon, U-shaped, with several small ponds scattered here 

 and there, and probably mainly inundated in very wet periods. One 



