22 A Canadian Arctic Expedition, 1913-1918 



Euastrum dubium Nag. (Plate III, fig. 12) 



A few individuals of this species were found in the collection from the 

 drying tundra pond at Demarcation point. From Chantry island five specimens 

 were seen, and all were approaching the variety Snowdoniense (Turn.) W. and 

 G, S. West. 



Euastrum elegans (Br^b.) Kiitz. 



This pretty and common species was abundant in several ponds at Teller, 

 and in the Hippuris swamp at Herschel island. 



Euastrum oblongum (Grev.) Ralfs 



This species was found fairly common in the collection from the lagoon lake 

 at Teller. It was not seen in any other collection although it is known to be 

 common in the arctic regions. 



Euastrum occidentale W. and G. S. West 



This species was the rarest of the genus; only two individuals were seen. 

 They occmred in the material from the drying tundra pond at Demarcation 

 point. May 14, 1914. It has been previously found in Nova Scotia and some of 

 the eastern states of the United States of America, and in one locahty in Great 

 Britain. Its distribution is apparently limited and it is here recorded from 

 arctic regions for the first time. 



Micrasterias Agardh. 



Micrasterias apiculata (Ehrenb.) Menegh. var. trachyptera (Lund.) W. and 

 G. S. West (Plate III, fig. 9) 



I was disappointed in not finding more than one species belonging to this 

 genus. This one was not common, for only a few empty semi-cells were seen. 

 AH were a little less spiny than is general in this variety, but they possessed the 

 very wide polar lobe which distinguishes it from the specific type. Hippuris 

 swamp, Herschel island, July 30, 1916. 



Cosmarium Corda. 



Gosmarium asphaerosporum Nordst. var. strigosum Nordst. 



(Plate III, fig. 15) 

 This is a very small desmid and easily overlooked, which fact may account 

 for the few records of it. The type form has a very limited distribution and has 

 been found in the United States of America and arctic regions of Europe and 

 Asia. The variety mentioned here was found in small numbers at Teller, and 

 has only been previously recorded from Sweden and one locality in England. 

 Specimens were below average size. 



Cosmarium binum Nordst. (Plate IV, fig. 6) 



This species is more frequent in the tropical zone than in the temperate, 

 and has not previously been recorded in arctic regions. A few individuals with 

 sufficient characters to show their relation to this species were found at Herschel 

 island. However, they differed from the type form in the following points: 

 smaller and proportionately shorter; more truncate; crenulations fewer, 15 to 

 each semi-cell; vertical granulate ridges only 5; length 44 m, breadth 36m, breadth 

 of isthmus 14^. 



