FIGURES 64–69 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 64–69: Cyclotella pseudokansasica. SEM. Figures 64, 65. External valve views. Prominent spines or spine bases are located about the periphery of the valves. Multiseriate fascicles alternate with thick costae. Openings of the marginal fultoportulae are located near the base of the mantle. Scale bars = 1 µm. Figures 66–69. Internal valve views. The valves have a few to several scattered central areolae, and marginal fultoportulae positioned on every second or third costa. Scale bars = 1 µm (in figs 64–66, 68, 69). Scale bar = 2µm (in fig. 67).