Anabaena borealis E. Larsen

Larsen E. Ferskvandsalger fra Vest-Grønland // Medd. om Grønland, 1907. XXXIII. P. 305-364.
In freshwater-plankton from Disko gathered by Poralld a form was found which I have not succeeded in referring to any of the species I have met with hitherto.
The filaments occurred singly. They are linear and furnished with a thick mucous sheath, especially around the vegetative cells, the mucous being less thick arround the spores;