THE GREEN ALGAE OF NORTH AMERICA 119 



seems hardly sufficient to justify transferring the name to this 

 species, from the so long recognized >S. longata Kiitz. 



Subgenus SIROGONIUM. Cells directly conjugating, without 

 formation of tube. 



38. S. STICTICA (Eng. Bot.) Wille, 1884, p. 34; P.B.-A.,No. 

 1366 ; Sirogonium sticticiim Petit, 1880, p. 34, PL VII, figs. 6-8; 

 Wolle, 1887, p. 222, PI. CXU, figs. 8-10. Filaments 38-54 /u. 

 diam., cells 2-4 diam. long; chromatophores 3-4, narrow, paral- 

 lel and straight or slightly curved ; fertile cells shortened but 

 only ver) r slightly swollen ; conjugation of cells direct, by gen- 

 icular bending towards each other of two filaments, the female 

 filament larger than the male ; each of the original filament cells 

 dividing into two, rarely three in the male filament ; of these 

 cells two, one from each filament, unite to form the spore, the 

 others remaining sterile ; spores ellipsoid, yellowish at maturity, 

 \y 2 diam. long, up to 60 /u. diam. Florida, Cal. 



So. America, Europe. 



Though this plant has long been kept as a distinct genus, its 

 inclusion in Spirogyra seems justified by an intermediate form, 

 Sirogonium ceylanicum Wittr. It is amply distinct from any 

 other American species by the combination of characters, linear 

 slightly spiral chromatophores and conjugation without forma- 

 tion of tubes. 



Doubtful species of Spirogyra. 



S. negleda Wolle, 1887, p. 216. 



5. subaequa Wolle, 1887, p. 217; appears to belong under 

 6*. bellis. 



S. rivularis Wolle, 1887, p. 220; the figures in PI. CXXXVI 

 do not agree with the descriptions of other authors. 



S. adnata Wolle, 1887, p. 220, PI. CXXXV, figs. 3 and 4, 

 seems indistinguishable from 5*. dedmina. 



S. elongata Wolle, 1887, p. 221, refers to PI. CXXXV, figs, 

 i and 2, but in the volume of plates these figures are indicated 

 as 5. insignis var. elongata ; the dimensions of the figures agree 

 best with 5. elongata, but under the circumstances it is uncer- 

 tain just what Wolle's plant was. 5. elongata Wood, 1872, p. 

 164, PI. XIV, fig. i is 5". tcnidssima (Hass.) Kiitz. 



3. DEBARYA Wittrock, 1872, p. 35. 



Cells cylindrical, about 5 times as long as broad; dissepi- 

 ments even ; chromatophore an axillary plate with several pyre- 

 noids ; conjugation between two filaments not differing in 



