FRESHWATER ALG^l. 33 



Genus OSCILLATORIA Vaucher. 



44. OSCILLATORIA PROBOSCIDEA. 



Oscillatoria proloscitlea Gom., torn, cit., p. 209, PL VI., figs. 10, 11. 

 Diam. trich. = 12 A. 



lt. Freshwater pond in ice off Black Island, McMurdo Strait, December 31st, 

 1902. 



Isolated filaments, very similar to Gomont's fig. 1 1. 



45. OSCILLATORIA SUBPROBOSCIDEA. 

 (PI. I., fig. 66.) 



Oscillatoria subproboscidea W. and G. S. West, op. cit., p. 293, PI. XXV., figs. 91-94. 



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

 ice, McMurdo Strait, September 12th, 1902 ; very rare. 



46. OSCILLATORIA IRRIGUA. 



Oscillatoria irrii/ua Kiitz., Phyc. gen. (1843), p. 189 ; Phycol. Germ., 1845, p. 160 ; Gomont, torn, cit., 

 pp. 218-219, PI. VI., figs. 22, 23. 



Diam. trich. = 7-8 /A. 



Hal. Gap pond, Winter Harbour, December 15th, 1903. 



47. OSCILLATORIA SIMPLICISSIMA. 



Var. ANTARCTICA var. n. 



(Plate I., figs. 60-64.) 



Oscillaloria simplicissima Gom., torn, cit., p. 219, PI. VII., % 1 (0. tennis f. aruginosa Sauter in Raben- 

 horst, Alg., 1874, No. 2383). 



Trichomatibus ssepe valde elongatis, flexilibus, plerumque flexuosis, inter cellulas 

 non constrictis, massa intercellulari inflate et refringenti interrupts, apice recto neque 

 a'ttenuato neque capitate ; cellula apicali superue hemisphaerica ; protoplasmate 

 homogeneo vel subgranuloso. 



Diam. trich. = 8 ju. ; long. cell. = 2-3 p.. 



Hal. Freshwater pond in ice off Black Island, McMurdo Strait, December 31st, 

 1902 (on surface of a sheet of Phormidktm an<ju*tissimum) ; pond among the eskers 

 which border the shore of the Western Mainland, December 2nd, 1902. 



The specimens differed from those described by Gomont in two important respects, 

 viz., their highly flexuous character and the abundant occurrence of inflated bi-concavc 

 intercellular masses (fig. 60). The apices of the trichomes were perfectly straight and in 



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