Wood.] -'■"^ [June 18, 



shorter, greatly swollen ; cell wall at each end produced or folded in ; 

 chlorophyll filament 1, spiral lax ; turns mostly 7 ; spores elliptical, 2-2|^ 

 times longer than broad. 



Diam. Spor. yJ^o =- .00106. Artie, vegetat. jJ^o -0005. 



Hab. In aquis limpidis prope Philadelphia. 



R. PULCHELLA. 8p. NoV. 



R. articulis sterilibus diametro 2-3 plo longioribus ; sporiferis nonni- 

 hil tumidis ; fascia unica ; anfractibus 3-4 ; sporis ellipticis, diametro 

 fere duplo longioribus ; cytiodermate utroque fine protense et replicato. 



Sterile joints 2-3 times longer than broad ; fertile joints somewhat 

 swollen ; chlorophyll band one ; turns of spiral 3-4 ; spores elliptical, 

 almost twice as long as broad ; cell wall at each end produced or 

 folded in. 



Diam. Artie. Steril. y/^o - js%^ = .00033 - .0013. Spar. jJ>^^ - ji^^ 

 = .0012 .00133. 



Hab. In stagnis prope Philadelphia. 



GEN. SPIROGYRA. 



S. WEBERI. KtZ. 



Bemarks. — The American form agrees pretty well with the European, 

 but is however, larger, its cells also a attain a greater proportionate 

 length, and their chlorophyll bands have more turns. The lower 

 limits of the American form are, however, so ovei'lapped by the upper 

 limits of the European, that it seems to me they must be considered 

 identical. 



Hab. In stagnis prope Philadelphia. 



S. DUBIA. Ktz. 

 Eemarks. — I have never seen the sporangial cell swollen in American 

 specimens, in other respects the agreement is complete. 

 Hab. In stagnis prope Philadelphia. 



S. QUININA. (Ag) Ktz. 

 Hab. In stagnis prope Philadelphia. 



s. RivuLARis. (Hassall), Rahenliorst. 

 Hab. In rivulis prope Hibernia, Florida. Mr. Wm. Canby. 



S. LONGATA. ( VciUCk), Ktz. 



Hab . In stagnis prope Philadelphia. 



s. iNsiGNis. {Hassall), Ktz. 

 Hab. In stagnis prope Philadelphia. 



S. PROTECTA. 8p. Nov. 



S. saturate viridis, lubrica ; articulis sterilibus diametro 6 plo longiori- 

 bus ; sporiferis vix tumidis ; cytiodermate in cellulse utroque fine pro- 

 tense et replicato ; fascia unica ; anfractibus 6 ; sporis oblongis vel ellip- 

 ticis : membrano crassissimo. 



S. Deep green, slippery ; sterile joints 6 times longer than broad ; fer- 



