30 A Canadian Arctic Expedition, 1913-1918 



Two-sided form: semi-cell 60 x 28m; sinus, breadth 30ai; length of whole 

 cell 66m. Four-sided form: semi-cell 60 x 50m; sinus 30m; length of whole cell 

 66m. 



The specimens examined by Wille were found on the gelatinous envelope 

 of a Protozoan colony, Ophrydium versatile. The majority of individuals I found 

 were also attached to the gelatinous wall of an Ophrydium colony, probably the 

 same species. They were fairly numerous, and it is possible that there is a com- 

 mensual relation between the two organisms. The Ophrydium mass was obtained 

 in the big lake at Bernard harbour, and in the same lake a few individuals of 

 this desmid appeared free in the plankton (July 3, 1916). It also occurred in 

 collections from Demarcation point and Chantry island. Distribution: Norway, 

 Austria, Nova Zembla, Arctic America. 



Staurastrum lunatutn Ralfs (Plate IV, fig. 11) 



A form of this species approaching S. tunguscanum Boldt was common in 

 the plankton collections from Teller. 



Staurastrum lunatum Ralfs var. planctonicum W. & G. S. West 



This variety was found in small numbers in the plankton of the big lake at 

 Bernard harbour. It is fairly common in the European Arctic plankton, but 

 not in that of the American Arctic. 



Staurastrum megacanthum Lund. 



This species occurred only in the Hippuris swamp at Herschel island, 

 where it was fairly abundant. It is not unknown from arctic regions but has 

 not been recorded from those of America. 



Staurastrum muricatum Ralfs 



This desmid was found in the plankton of the lagoon lake at Teller and was 

 not infrequent. It has about the same distribution as the last species. 



Staurastrum muticum Br^b. 



This species was far more common and occurred in three localities. It was 

 found in the lagoon lake at Teller, in the Hippuris swamp at Herschel island, 

 and in the big lake and amongst other algae from the river bed at Bernard 

 harbour. 



Staurastrum orbiculare Ralfs 



This species was fairly common in the lake at Teller. It is frequent 

 throughout the United States but not in the arctic parts of America, although 

 common in Spitzbergen and Nova Zembla. 



Staurastrum pachyrhynchum Nordst. (Plate IV, fig. 14) 



This is a species common in northern regions and has been found frequently 

 in arctic waters. However, it was not common in these collections, appearing 

 in small quantity only from Herschel island. 



Staurastrum paradoxum Meyen 



This species is one of the most frequent in some Canadian lakes but was 

 exceedingly rare in the arctic material. Two specimens were seen from 

 Demarcation point, and a poorly developed one from Herschel island. 



