16 A Canadian Arctic Expedition, 1913-1918 



Selenastrutn Reinsch. 



Selenastrutn acuminatum Lagerh. (Plate III, fig. 3) 



• This species occurred only in a collection of bottom deposits and plankton 

 from Teller, August 6, 1913. 



Scenedesmus Meyen. 



Scenedesmus denticulatus Lagerh. 



This species was the rarest of the genus. It was found only in small quantity 

 in the bottom deposit collections from the lake at Teller. 



Scenedesmus obliquus (Turp.) Kiitz. 



This species, although not common, occurred in more localities than the 

 preceding species. It occurred in the lagoon lake at Teller, in the plankton at 

 Bernard harbour, and in the Hippuris swamp at Herschel island. The Dacty- 

 lococcus stage was found with the Ophrydium mass at Bernard harbour. 



Scenedesmus quadricauda (Turp.) Br6b. 



This alga was very common in the collections from Teller. It was found 

 in smaller quantities at Bernard harbour. Demarcation point, and Herschel 

 island. 



Crucigenia Morren. 



Crucigenia rectangularis (Nag.) Gay 



This species occurred only in the plankton of the big lake at Bernard harbour. 

 The cells were a little below average size, being 3-5;u to 5fi by 4|i to 6^. The 

 colonies usually contained 8 or 16 cells. 



Crucigenia sp? 



In the collections from Bernard harbour with C. rectangularis were 

 seen a few colonies of 4 and 8 cells of a species abour one-half of the size of 

 C. rectangularis, i.e., 2 to 2-5^ by 2-5/i to 3/*. The cells were badly collapsed. 

 This condition was probably caused by the alcohol in which they were preserved. 

 I could not therefore determine the species with accuracy. It resembled 

 C. rectangularis in general appearance and is probably a small variety of that 

 species; but to make sure of its exact systematic position material in a better 

 state of preservation would be required. 



Coelastrum Nag. 

 Coelastrum microporum Nag. 



This species occurred in two localities only and was not very plentiful in 

 either of them. It was found in the plankton at Bernard harbour (September 

 26, 1916) and in the Hippuris swamp at Herschel island. 



Coelastrum reticulatum (Dang.) Senn. 



Three individuals of this peculiar species of Coelastrum were found in 

 material at Herschel island in the Hippuris swamp. It is not a common alga 

 in North America. It has been recorded from Put-in-Bay, Lake Erie (Snow), 

 and I have recently found it in Manitoba and Ontario. It is not generally found 

 in arctic regions. 



