FRESHWATER ALG^E. 57 



PLATE III. 



FIGS. 123-125. Noxtoc disciformc sp. n., young colonies. (12:!, x 140 ; 124-125, x 500.) 



FIG. 12(!. Nnstof tlisciforme sp. n., thalli. (Natural size.) 



Fins. 127-130. Noxtoc diseiforme sp. n. 127, 128, two filaments ; 127, with spores ; 129, two groups of 



spores ; ISO, filament with sheath. (127, 128, 1:50, x 500 ; 129, x 700.) 

 FIG. 131. Nfistni- (Hseiforme sp. n., small part of a mature thallus. (x 30.) 

 FIG. 132. Nostoc longs tuffi sp. n., thalli. (Natural size.) 

 FIGS. 133-134. Nostnc lont/staffi sp. n., young colonies, (x 500.) 



FIGS. 135-136. filaments with spores. (135, X 700 ; 136, X 500.) 



FIG. 137. smr.ll part of a mature thallns. (X30.) 



FIG. 13H. Nostoc fmcescens sp. n., thalli. (Natural size.) 

 FIG. 13!). a young thallus. (x400.) 



FIGS. 140-142. filaments. (140, 142, X 700; 141, X 500.) 



FIGS. 143-144. young thalli. (x800.) 



FIGS. 145-146. Tolypothrlc contjlutinata 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 U'Ja.Melosira sp., ef. p. 46. (x 1350.) 

 FIG. 150. ?Cyclotella operculata Kiitz. (x 550.) 

 FIG. 151. Coscinodiscus decipiens Grun. (x 1250.) 

 FIGS. 152 and 152. Diatoma elonyalum Ag., var. ehrenlergi (Kiitz.) W. Sm. ; 152, girdle-view ; 



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

 FIG. IbZ.Navimla lorealis (Ehrb.) Kiitz. ( x 900.) 

 FIGS. 154, 155. Navicula glolticeps Greg.; 154, f. amphkephala ; 155, f. elongata. (154, x 1250 ; 



155, X 850.) 



FIGS. 156, 157. Denticula tennis Kiitz. var. anlarctica var. nov. (156. X 1250 ; 157, X 1500.) 

 FIGS. 158-160. Calothrix 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; 1C>0, x 500.) 

 FIGS. 161-163. Calothrix antairtica sp. n. ; 161, 102, filaments showing false branching. (161, 162, 



X 400 ; 163, X 550.) 

 FIGS. 164-172. Calothrix gracilis sp. n. 164, filament showing false branching; 165, 172, typical 



filaments ; 166, 167, base of two filaments, showing inflation ; 170, part of a filament 



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



(164, 165, x 500 ; 166-169, 171, 172, X 700 ; 170, X 1200.) 



2 



