nostochineæ

from The Century Dictionary.

• A subclass or group of algæ, of the class Cyanophyceæ, including the families Nostocaceæ, Rivulariaceæ, Scytonemaceæ, and Oscillariaceæ, in which the individual consists of a cellular or pseudocellular filament, reproduced by motile hormogonia, and in some families forming heterocysts.