As with Pinnularia (Vol. 1), this is a revision and synopsis of Navicula sensu stricto, another 10 genera previously included in Navicula sensu lato, and of Frustulia. The synopsis covers the temperate zone of the northern hemisphere, with emphasis on Europe. The revision however is more general in its coverage of the temperate and colder zones, and includes some remarks on taxa from the (sub-)tropics. Additionally, reference to the diatom floras of the Pleistocene and Neogene (Tertiary) are made.