32 TUFTS COLLEGE STUDIES, VOL. IV, No. 7 



sides and pointed ends, with 15-25 disk-shape chromatophores 

 with distinct pyrenoids ; cells 30-35 /* long, median diani. 

 11-14 ft, max. diam. 12-15/1- Wis., G. M. Smith. 



The typical form, W. & G. S. West, 1894, p. 15, PI. II, figs. 

 33-35, of about double these dimensions, has not been reported 

 in this country. 



10. O. ELLIPTICA W. West, 1892, p. 736; Printz, 1913, 

 p. 182, PI. IV, fig. 33. Cells elongate-ellipsoid, with ends 

 rounded, not thickened, 22-25 X 11-12 /*, rarely solitary, mostly 

 in 4-8 celled families ; chromatophores 10-20, without pyrenoid. 

 Mich., Transeau. Europe. 



Var. MINOR, W. & G. S. West, 1894, p. 14, PI. II, fig. 26, 

 Cells 15-22 X 7-10/1. Wis.. G. M. Smith. Europe. 



11. O. GLOEOCYSTIFORMIS BorgC, 1906, p. 23, PI. II, fig. I. 



Cells ellipsoid, with a thickening and a short, acute prolonga- 

 tion at each pole, 9 X 4-5 /*, 2 to several in a family, families 

 several in a general gelatinous coating, showing more or less 

 distinctly successive mother-cell walls. Wis., G. M. Smith. 



/ del Fuego. 



12. O. RUPESTRIS Kirchner, 1880, p. 169, PI. II, fig. 2; 

 Print/., 1913, p. 174, PI. IV, figs. 7-9 ; Wittr. & Nordst., Alg. 

 Kxsicc., Nos. 725, 1248. Cells oblong-ellipsoid, 13-28 X 6-12 ft, 

 poles rounded, not thickened ; chromatophores 1-2, with pyre- 

 noid ; mother cell wall soon dissolving, hence cells usually 

 solitary. Wis., G. M. Smith. Northern Europe. 



GLAUCOCYSTIS Itzigsohn in Rabenhorst, 1868, p. 417. 



Cells ellipsoid or ovoid, solitary or 2-8 in a family enclosed 

 by the mother cell wall ; chromatophores blue-green, in younger 

 cells many and scattered, later filiform and radiating stellately 

 from a central vacuole ; asexual reproduction by autospores, 

 usually 4 in a cell. 



G. NOSTOCHINRARUM Itzigsohn in Rabenhorst, 1868, p. 417 ; 

 G. S. West, 1916. p. 40, fig. 24. Cells ellipsoid. 18-28 X 

 10-18 /*, membrane thin. Fig. 10. Scattered among other algae 

 in quiet water. Mass. I', it rope. 



This genus has often been placed among the Myxophyceae, 

 on account of its color, but its other characters seem to place it 

 better in the Chlorophyceae, near Oo, 



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