In Mr. Bullard’s collection there are specimens of this species from Lexington, Arlington, and Middlesex Fells, Mass. The P. B.-A. specimen No. 362, labeled _S. Grevilleana_, from Medford, Mass., belongs here, rather than to _S. Grevilleana_, in which the spores are distinctly ovoid with broad rounded ends. =S. groenlandica= Rosenvinge. This interesting form is characterized by quadrately inflated fertile cells, highly refractive cell walls, and unusually long cells and spores. In Mr. Bullard’s collection there are specimens from Stony Brook, South Framingham, Middlesex Fells, Wayside Inn, North Eastham, and Malden Fells, Massachusetts. The P. B.-A. specimen No. 363 labelled _S. inflata_, Orange, Conn., belongs to this species. =S. fallax= (Hansgirg) Wille. This species is one of several forms near _S. insignis_ (Hass.) Kützing. If Wille’s description is correct and identical with Hansgirg’s material, then _S. inconstans_ Collins becomes a synonym of _S. fallax_. Hansgirg’s figure suggests that the filaments in his material are homosexual. While Wille’s description and figure suggests that the filaments are reflexed and that conjugation does not regularly occur between parallel filaments, with the spores all in one filament. It is difficult to decide just where these rough-spored forms belong as the earlier authors did not pay much attention to spore markings. In this connection the note by Professor Nordstedt in connection with specimen No. 958 in Wittrock and Nordstedt’s Algae Exsiccatae is of interest. Until these forms have been clearly separated by a study of the original collections it seems best to use _S. fallax_ for _S. inconstans_, of which the type is P. B.-A. No. 1568. Here also belongs P. B.-A. No. 1570, Middlesex Fells, Mass., and P. B.-A. No. 1571, Wakefield, Mass. =S. floridana= nov. sp. Cellulis vegetativis 56-66µ × 120-335µ, dissepimentis planis; chromatophoris 4-5, subrectis vel anfractibus arctis .5; cellulis conjugatis abbreviatis, inflatis (ad 135µ) et geniculatis; canalis conjugationis brevis et latis; zygosporis ellipticis, 75-105µ × 95-135µ membrana media glabra, lutea. Vegetative cells 56-66µ × 120-335µ, end walls plane; 4-5 chromatophores, nearly straight or making a half turn; conjugating cells geniculate, shortened; fertile cells inflated up to 135µ; conjugating tube very short and broad; zygospores ellipsoid, 75-105µ × 95-135µ median wall smooth, yellow. Type in U. S. National Herbarium, collected by J. D. Smith, in S. W. Florida, March, 1878.