FRESH WATEE ALGM. 57 



PLATE III. 



Figs. 123-125.— iVosioc disciforme sp. n., young colonies. (123, X 140 ; 124-125, x 500.) 



Fig. 126. — Nostoc disciforme sp. n., tlialli. (Natural size.) 



Figs. 127-130. — Nostoc disciforme sp. n. 127, 128, two filaments ; 127, with spores ; 129, two groups of 



spores ; ISO, filament with sheath. (127, 128, 130, x 500 ; 129, x 700.) 

 Fig. 131. — Nostoc disciforme sp. n., small part of a mature thallus. (X 30.) 

 Fig. 132.— iVostoc longsiaffi sp. n., thalli. (Natural size.) 

 Figs. 138-134. — Nostoc longstaffi, sp. n., young colonies, (x 500.) 



Figs. 135-136. „ „ „ filaments with spores. (135, x 700 ; 136, X 500.) 



Fig. 137. „ „ „ smdl part of a mature thallus. ( X 30.) 



Fig. 138. — Nostoc fuseescens sp. n., thalli. (Natural size.) 

 Fig. 139. „ „ „ a young thallus. ( x 400.) 



Figs. 140-142. „ „ filaments. (140, 142, x 700 ; 141, x 500.) 



Figs. 143-144. „ „ young thalli. (x 800.) 



Figs. 145-146. — Tolypothrix conglntinata Borzi. 145, a small part of the richly branched filament ; 



146, the end of one of the branches. ( x 500.) 

 Fig. 147. — Fragilaria curta Van Heurck. (x 1350.) 

 Figs. 148, 149 and ll'ia.—Melosira sp., cf p. 46. (x 1350.) 

 Fig. 150. — ? Cyclotella operculata Kiitz. (x 550.) 

 Fig. 151. — Coscinodiscus decipiens Gtuti. (x 1250.) 

 Figs. 152 and 152a. — Diatoma elongafum Ag., var. ehrenbergi (Kiitz.) W. Sm. ; 152, girdle-view ; 



152«, valve-view. (152, x 1950 ; 152fl, x 1350.) 

 Fig. IbS.—Navicula lorealis (Ehrb.) Kiitz. (x 900.) 

 Figs. 154, 155. — Navicula globiceps Greg. ; 154, f. amphicephala ; 155, f. elongata. (154, x 1250 ; 



155, X 850.) 

 Figs. 156, 157. — Denticula tenuis Kiitz. var. anfarclica var. nov. (156, X 1250 ; 157, X 1500.) 

 Figs. 158-160. — Galothrix intricata sp. n. ; 158, a typical part of the stratum (the trichomes are only 



shown in two cases) ; 159, 160, single filaments. (158, X 400; 159, X 800; IGO, X 500.) 

 Figs. 161-163. — Galothrix antarctica sp. n. ; 161, 162, filaments showing false branching. (161, 162, 



X 400 ; 163, X 550.) 

 Figs. 164-172. — Galothrix gracilis sp. n. 164, filament showing false branching ; 165, 172, typical 



filaments ; 1G6, 167, base of two filaments, showing inflation ; 170, part of a filament 



showing an intercalary heterocyst ; 171, base of filament with a subconical heterocyst. 



(1G4, 165, X 500 ; 166-169, 171, 172, X 700 ; 170, X 1200.) 



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