MIDDLESEX FLORA. 153 



Delesseria, Lamour. 



D. sinuosa, Lamour. 

 Mystic river, below low water mark. Rare. 



Gracilaria, Grev. 



G. multipartita, Ag., var. angustissima, Harv. 



Medford, Everett, et al., in ditches in salt marshes. Not rare. 



HiLDENBRANTiA, Nardo. 



H. rosea, Kuetz. 

 On pebbles in Mystic river, between tide marks. Not common. 



Ehodymenia, Grev. 



R. palmata, Grev. Dulse. 

 Mystic river, below low water mark. Xot common. 



Chondrus, Stack. 



C. crispus. Stack. Irish Moss. 

 Mystic river and salt marshes, common. 



Ceramium, Lyng. 



C. rubrum, Ag. 



Mystic river and salt marshes, common. 

 C. strictum, Harv. 

 Same locality as the preceding, but less common. 



Sacheria, Sirdt. 



S. rigida, Sirdt.? 

 Melrose, growing in masses on perpendicular rocks in " The Cas- 

 cade." The determination is not quite certain, as this is one of the 

 many forms which have heretofore been included in Lemanea toru- 

 losa, and only recently distinguished by Sirodot. 



Batrachospermum, Roth. 



B. vagum, Ag. 



Billerica (Edwin Faxon). 

 B. moniliforme, Rotli. 

 Not uncommon in running water in spring and early summer. 

 This genus and the preceding are the only fresh water Florideas yet 

 found in the county. 



PORPHYRA, Ag. 



P. laciniata, Ag. 



Somerville, on woodwork in Mystic river, between tide marks. 



