1905.] natural sciences of philadelphia. 697 



Brackish Marsh Formation. 



This exists in depressions some distance inland where marshes occur 

 such as Smith's Parish Marsh, Devonshire Marsh, Pembroke Marsh 

 all of which were investigated by me. Smith's Parish Marsh is devoid 

 of trees. Here in the soil rendered brackish by underground channels 

 grow Typha angustifolia in pure association, Baccharis heterophylla in 

 thickets (Baccharis Association,) Dichromena leucocephala, Scirpus 

 lacustris, while Osmunda cinnamomea is frequent. Acrosticum aureum 

 forms pure associations at the edge of this marsh. 



Devonshire Marsh is a large area with a few pools of water in the de- 

 pressions. It gives evidence that it was once a pond. Juniperus her- 

 mudiana, Sabal Blackburniana and Baccharis heterophylla have en- 

 croached on this marsh so as to shade it. On the ground in the wettest 

 places, according to Coulter,^ are Hydrocotyle asiatica, Herpestis mon- 

 nieria, Mentha viridis and a white bracted sedge, Dichromena leuco- 

 cephala. On the drier ground, Osmunda regalis and 0. cinnamomea 

 become abundant, while in the still drier peaty soil, according to my 

 observations, Pteris (Pteridium) aquilina caudata is growing vigorously. 

 Here also occur two other plants, Cladonia and Leucobryum. Typha 

 angustifolia is in some places in pure association. Acrosticum aureum 

 also forms pure association here and there in this marsh. The pools 

 are occupied by two species of Sphagnum, Proserpinaca palustris 

 and Lemna minor. Pembroke Marsh is characterized by somewhat 

 similar associations of plants; but in addition to the plants noticed 

 above. Governor Lefroy^ mentions several other plants pecuhar to 

 it, such as Nasturtium officinale (in water channels), Ascijrum crux- 

 andrece, Kosteletzkya virginica, Waltheria americana ( =indica), Eclipta 

 erecta, Pluchea odorata, Ceratophyllum demersum, Kyllinga monocephala, 

 Scirpus validus, Cladium occidentale ( = germanicum) and Spiranthes 

 brevilabrus, the only orchid of Bermuda. The omnipresent cedar is 

 found along the edge of this marsh together with Sabal Blackburniana 

 which invades it. In a small pool grows Lemna minor. 



Sand Dune Formation. 



Sand dunes occur typically along the south shore of Bermuda ^t the 

 head of reentrant bays between stretches of rocky coast. Several low 

 dunes are found on the north shore as at Shelly Bay. The middle 



' Coulter, Samuel Monds : An ecological Comparison of some typical Swamp 

 Areas, Fifteenth Report Missouri Bot. Garden, 1904, p. 62. 



'Lefroy, General Sir John Henry: The Botany of Bermuda, Bulletin U. S. 

 National Museum, No. 25. 1884. 



