Freshwater Diatoms 43 a 



Navicula palpebralis Br^b. var. semiplena Greg. 



This variety was not uncommon in some of the collections from the lake at 

 Teller. With them were a few specimens which seemed to be intermediate 

 between this variety and N. elegans W. Sm. 



Navicula punctulata W. Sm. 



This was only found in the same collections as the last mentioned species 

 and is a freshwater form. It was slightly more numerous. 



Navicula radiosa Kiitz. 



This species was found only in one sample taken from the big lake at 

 Bernard harbour, September, 1915. 



Navicula Silicula Ehr. 



This species was found in small numbers in the lagoon pond at Teller, and 

 once in the brackish pond in that locality. 



Navicula Smithii Breb. 



This is a marine species occurring only in a few samples obtained July, 

 1913, at Teller. It was not very plentiful. Some of the specimens were some- 

 what rhomboid in outline and may represent a new variety of the species. 



Pleurosigma W. Sm. 



Pleurosigma angulatum W. Sm. var. strigosum W. Sm. 



This is another of the marine forms appearing only at Teller. The oblique 

 lines on the valves cut each other at an angle of 55°. 



Pleurosigma attenuatum W. Sm. 



This was fairly common in some of the collections. It was found at Teller, 

 CoUinson point, Bernard harboiir, and in the stomach of a fish taken at the latter 

 place, October 4, 1915. 



Pleurosigma Fasciola W. Sm. 



This species was found a few times in the material from the brackish pond 

 at Teller. It is normally a marine species. 



Pleurosigma hippocampus W. Sm. 



This is a brackishwater species that appeared in a brackish pond at Teller. 

 It was not plentiful. 



Amphipora (Ehr.) Cleve. 

 Amphipora ornata Bail. 



This species appeared in collections from Teller, in the lagoon pond, in a 

 tundra pond at Colhnson point, and also in the big lake and brackish pond at 

 Bernard harboiir. 



GOMPHONBMEAE. 



Gomiphonema Ag. 

 Gomphonema cristatum Ralfs 



This species appeared in very small quantities in three localities, in the 

 Hippuris swamp at Herschel island, in the bed of the warm creek in northern 

 Alaska (near Sadlerochit river), and in a bottom sample from the lake at 

 Bernard liarbour. 



COCCONEIDBAE. 



Cocconeis (Ehr.) Grun. 

 Cbcconeis placentula Ehr. 



This species occurred only in two collections from Bernard harbour, viz.: 

 from tbe .ereek mouth, July, 1915, and in a mud sample from the lake bottom, 

 Eebruary, 1916. 



