FEESHWATEE ALG^, 33 



Genus Oscillatoria Vaucher. 



44. Oscillatoria proboscidea. 



Oscillatoria proioscidea Gom., torn, cit., p. 209, PI. VI., figs. 10, 11. 



Diam. trich. = 12 //.. 



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

 1902. 



Isolated filaments, very similar to Gomont's fig. 11. 



45. Oscillatoria subproboscidea. 



(PI. I., fig. 66.) 



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



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

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



46. Oscillatoria irrigua. 



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

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



Diam. trich. = 7-8 /a. 



Hab. — Gap pond. Winter Harbour, December 15th, 1903. 



47. Oscillatoria simplicissima. 



Var. ANTARCTICA var. n. 



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



Oscillatoria simplicissima Gom., torn, cit., p. 219, PL VII., fig/. 1 {0. tenuis f. ceriiginosa Sauter in Eaben- 

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



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

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

 attenuate neque capitate ; cellula apicali superne hemisphserica ; preteplasmate 

 homogenee vel subgranuleso. 



Diam. trich. = 8 ft ; long. cell. = 2-3 /a. 



Hab. — Freshwater pond in ice ofi" Black Island, McMurdo Strait, December 31st, 

 1902 (on surface of a sheet oi Phormidium angustissimum) ; pond iamong 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-concave 

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



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