FIGURES 32–37 in Morphology of some fossil lacustrine centric species from the western United States assigned to the genus Cyclotella (Bacillariophyta), including four described as new

FIGURES 32–37: Cyclotella discostelliformica. SEM. Figures 32, 33. External views showing valves with sunken and elevated central areas, respectively. Fascicles are composed of 2–5 rows of areolae. Openings of the marginal fultoportulae are located at or near the thickened ribs. They lack tubes or thickenings. The central portion of the valves have isolated areolae, that are larger than those of the fascicles. Scale bars = 1 µm. Figures 34–37. Internal valve views showing a single central fultoportula with 3 satellite pores, and marginal fultoportulae at every costa or every second costa. The rimoportula is located on or near a costa (arrows). Scale bars = 1 µm.