22 F. E. FRITSCH. 



17. CHROOCOCCUS MINOR. 

 Chroococcus minor (Kiitz.) Nag., op. eit., p. 47, Tab. I., fig. A4 ; Habenhorst, op. cit., p. 30. 



Hob. Gap pond, Winter Harbour, December 15th, 1903 (on Phor mid turn}. 



18. CHROOCOCCUS HELVETICUS. 

 Chroococcus helveticm Nag., op. cit., p. 46, Tab. I., fig. A3 ; Rabenhorst, op. cit., p. 31. 



Diam. cell. = 5 /A. 



Hob. Gap pond, Winter Harbour, December 15th, 1903 (on Phormidium). 



Very typical colonies of exactly spherical cells ; colonies composed of 4-8-16 cells. 



Genus DACTYLOCOCCOPSIS Hansg. 

 19. DACTYLOCOCCOPIS RHAPHIDIOIDES. 



(PI. II, figs. 116, 117.) 

 Dactylococcopsis rliaphidioides Hansg., Prodr. d. Algenfl. v. Bohmen, ii. (1892), p. 139, fig. 49a. 



Diam. cell, in media parte = 2-3 \i ; long. cell. = 25-27 p.. 



Hob. Freshwater pond upon ice among eskers, four miles north of Black Island, 

 McMurdo Strait, September 12th, 1902. 



The individuals were slightly longer than those described by Hansgirg, and were 

 all of semilunar shape ; the contents were pale blue-green, with a few small granules, 

 and pronouncedly vacuolar ; the ends of the cells were pointed and colourless. Some 

 of the cells showed a distinct septum across their middle. 



20. DACTYLOCOCCOPSIS ANTARCTICA sp. n. 

 (PL II., figs. 121, 122.) 







Cellulis minutis, numerosis in muco hyalirio nidulantibus, stratum planum in 

 superficiem algarum Cyanophycearum formantibus ; cellulis irregulariter dispositis, 

 fusiformibus vel in alterutro fine rotundatis, rarius leniter curvatis, coutentu dilute 

 serugineo cum granulis paucis, membrana tenui ; propagatio divisione paulo 

 obliqua fit. 



Diam. cell. = 1 5-2 p. ; long. cell. = 4-6 p.. 



Hub. Forming an extensive flat stratum on the surface of the thallus of 

 Nostoc commune, Granite Harbour, New Bay, January 20th, 1902. 



The cells of this minute species are in the majority of cases spindle-shaped ; in 

 occasional cells however one end is rounded or one side may be almost flat. Curved 

 cells are rare. The ends of the cells are not protruded in any way and are 

 not colourless. 



