FRESHWATER ALG. 
Su) 
on 
There was occasionally very little constriction between the cells. Some of the 
filaments bore apical bacterial clusters. 
50. OSCILLATORIA FORMOSA. 
Osecillatoria formosa Bory, Dict. class. @hist. nat., xii. (1827), p. 474; Gomont, tom. cit., pp. 230-231, 
Pl. VIL, fig. 16. 
Diam. trich. = 5 p. 
/lab.—Damp spot, summit of Cape Adare, January 9th, 1902. 
This form occurred in tufts attached to the surface of Prasiola crispa. The 
trichomes showed no indication of constriction at the dissepiments, but Gomont’s 
figure also shows nothing of the kind. Although many of the trichomes were 
tapering and hooked, others in the same tuft were straight at the apex, not tapering 
and obtuse. The trichomes often exhibited a slight terebriform character (e/. O. 
Borge, Algen aus Argentina und Bolivia, Arkiv f. Botanik, VI., No. 4 (1906), p. 11). 
51. OSCILLATORIA PRODUCTA. 
(Ele i ire. 65s) 
Oscillatoria producta W. and G. 8. West, op. cit., p. 294, Pl. XXY., figs. 86-90. 
/Tah.—Freshwater pond among eskers, four miles north of Black Island, upon 
ice, McMurdo Strait, September 12th, 1902. 
Only a few trichomes of this species were seen. They were quite straight 
with a straight tip, which was rather longer than shown in any of Messrs. West’s 
ficures (cf. fig. 65). The cell-contents were highly granular. 
52. OSCILLATORIA BREVIS. 
Oscillatoria brevis Kiitz., Phye. gen. (1843), p. 186 ; Gomont, tom. cit., pp. 229-230, Pl. VIL., figs. 14, 15. 
Diam. trich. = 4-7 »; cellulis diametro }—1plo longioribus. 
Hab.—Freshwater pond among eskers, four miles north of Black Island, upon 
ice, McMurdo Strait, September 12th, 1902; pond among eskers, bordering shore 
of Western Mainland, December 2nd, 1902. 
The trichomes were frequently interrupted by inflated masses of intercellular 
substance. 
53. OSCILLATORIA DEFLEXA. 
Osecillatoria aeflera W. and G. 8. West, op. cit., p. 295, Pl. XXV., figs. 95-97. 
[ab.—F¥reshwater pond in ice, off Black Island, MeMurdo Strait, December 
31st, 1902 (floating among Nodularia hoettlitzi and Oseillatoria tenuis). 
