390 PROCEEDINGS OF THE ACADEMY OF [Aug., 



occurs, the following marsh strips may be recognized, beginning with 

 the outer one, which consists of Spartina stricta maritima (sp. gr. 1.003). 

 Then comes a strip of Spartina patens and a middle one of Panicum 

 virgatum, filled in between with Spartina patens and S. polystachya. 

 In the shoreward strip at the edge of the woods, where the salt marsh 

 vegetation merges with the fresh water vegetation (sp. gr. 1.000), 

 occur clumps of Cicuta maculata, Iris versicolor, Hibiscus moscheutos, 

 Polygonum sagittatum, P. pennsylvanicum, P. arifolium, Eryngium 

 virginianum, Ptilimnium capillaceum, Hydrocotyle umbellata, Lobelia 

 cardinalis, Convolvulus sepium and Impatiens fulva (visited by hum- 

 ming birds). The third strip may be considered to be the tension one, 

 where there is a gradual blending of the salt water and fresh water 

 vegetation. As one ascends the stream the salt marsh plants dwindle, 

 until not a trace of them is left and the marsh becomes entirely a fresh 

 water marsh, covered with plants which lower down merely fringed the 

 inner margin of the salt marsh. 



Sylvan Lake is the receptacle for the fresh water of a small stream 

 which rises in two forks in Mt. Prospect Cemetery, west of Ocean 

 Grove (80 feet contour). These two branches unite in a small pond 

 at Ocean Grove Heights, and the main stream flows seaward a distance 

 of a mile, until it enters Sylvan Lake (Duck Pond of the survey map), 

 which is about three-quarters of a mile long. As Sylvan Lake is shut 

 off from the ocean by a low sand bar, with a timbered sluiceway still 

 connecting it with the sea during high tides, it is sometimes supplied 

 with salt water, which enters the pond by means of the usually dry 

 sluiceway, which has been left as a means of keeping the water level of 

 the lake within certain limits. We can divide the vegetation of the 

 lake basin into two main divisions: (1) The vegetation uninfluenced 

 or rarely influenced by salt water, and growing in the western part of 

 the pond where the water is kept fresh by the stream which enters at 

 this end, and (2) the vegetation influenced more or less directly by 

 the sea water, when it enters by the sluice during exceptionally high 

 tides, which may rise high enough to enter the pond only three or four 

 times each year, and in the winter time, when the vegetation in the 

 pond, and surrounding it, being in its winter state, would be very little 

 injured by an overflow of salt water. Consequently the water of most 

 of the pond, especially near the landward end, is fresh, while near the 

 seaward end it is usually fresh, but brackish only after the sea water 

 has entered the pond during some high side, enabling a few salt marsh 

 species to persist, although generally subjected to fresh water con- 

 ditions (see note 9). 



