MIDDLESEX FLORA. 155 



SCYTOSIPHON, Thuret. 



S. lomentarius, Ag. 



Mystic river and salt marshes. 



RALFSIA, Berk. 



R. verrucosa, Aresch. 



On pebbles, etc., in Mystic river and salt marshes. 

 R. clavata, Crouan. 



Same localities as the last, and rather more common. 



LEATHESIA, S. F. Gray. 



L. difformis, Aresch. 



Ditches in Mystic river salt marshes ; a rather reduced form, and 

 not very common. 



ECTOCARPUS, Lyng. 



E. littoralis, Lyng. 



Mystic and Charles rivers, on stones and woodwork between tide 



marks. Not uncommon. 

 E. confervoides, Le Jolis. 



Medford salt marshes. 

 E. confervoides, Le Jolis, var. siliculosus, Kjellman. 



With the type. 



PH^EOSACCION, Farlow. 



P. Collinsii, Farlow. 



Mystic river, growing on Zostera marina. This species, the only 

 one of the genus, has been found only along the shore from Boston 

 to Nahant. 



"Fronds olive-brown, tubular, or saccate, composed of a single 

 layer of cells disposed in fours. Hairs wanting. Reproduction 

 by zoospores produced singly (?) in each cell. Fronds subgelati- 

 nous, gregarious, compressed-cylindrical, i inch to 1 inch broad, 

 about 2 to 8 inches long, at first saccate, becoming cylindrical, apex 

 at length ruptured. Cells squarish, .0038 to .007mm. broad; 

 frond .008 to. 01 mm. in thickness." W. G. Farlow in Bull. Torr. 

 Bot. Club, IX., 65. 



CHLOROSPOREyE. 



BRYOPSIS, Lamour. 

 B. plumosa, Ag. 



Between tide marks on the muddy banks of Mystic river, not 

 common. 



