Freshwater Algae 13 A 



Aphanothece Nag. 

 Aphanothece saxicolor Nag. 



Only one small irregular mass of this sjpecies was observed, cells 1 • 5/i wide 

 and 2| times as long. It was found in the big lake, Bernard harbour, August, 

 1915. It has not been recorded previously for the arctic regions of America. 



Microcystis Ktitz. 



Microcystis aeruginosa Ktitz. [Clathrocystis aeruginosa (Kiitz.) Henfry] 



This typical plankton alga is common in the United States of America but 

 has not previously been found in arctic regions. It is not uncommon in sonde 

 Canadian lakes. It was found by the expedition in the plankton of the big 

 lake at Bernard harbour and in the second bay east of Bernard harbour and 

 at Herschel island. 



Gomphosphaeria Kiitz. 



Gomphosphaeria aponina Ktitz. (Plate IV, fig. 18) 



A few pale blue-green colonies of this species were found in the plankton 

 of the big lake at Bernard harbour, July, 1916. It has not been previously 

 recorded from arctic America. 



Coelosphaerium Ktitz. 

 Coelosphaerium Kiitzingianutn Nag. 



This species was observed on various occasions in the plankton from 

 Bernard harbom: and once in some tundra material from Demarcation point, 

 Alaska. This is also a first record for the American arctic regions. 



Merismopedia Meyen. 



Merismopedia glauca (Ehrenb.) Nag. 



This was observed in material from the pond near the second bay east of 

 Bernard harbour, June, 1915, and in material from Herschel island, July, 1916. 



Merismopedia tenuissima Lemm. 



Although this species was never plentiful, it was observed in different 

 plankton collections from the lake at Bernard harbom- and at Herschel island. 

 No previous records have been made for the last two species for arctic America. 



OSCILLATORIACEAE. 



Oscillatoria Vauch. 

 Oscillatoria tenuis Agardh 



This species is well known from all arctic regions and occurred at CoUinson 

 point, Pihumalerksiak island, and Bernard harbour. 



HOKMOGONEAE. 



NOSTOCACEAE. 



Nostoc Vauch. 

 Nostoc commune Vauch. 



This was very plentiful at the bottom of tundra ponds and in many other 

 places at Teller. It was also found at CoUinson point and at Bernard harbour, 

 as weU as in the stomach of a fish taken June 20, 1915, at Bernard harbour. 



Nostoc sphaericum Vauch. 



This species was not by any means abundant and only occurred in a few 

 samples from Bernard harbour. 



