FIGURES 72–77 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 72–77: Cyclotella jonesii. SEM. Figures 72, 73. External valve views of Morphotype 1. Fascicles are comprised of fine areolae, while the tangentially undulate center has larger areolae. Marginal fultoportulae have tubular external openings, located on or about every other costa. Scale bars = 10 µm, respectively. Figure 74. External valve view of Morphotype 2. Multiseriate fascicles are comprised of areolae much smaller than those in the center of the valve. Scale bar = 2 µm. Figure 75. Internal valve view of Morphotype 1. Thick and thin costa are present. Central areolae are numerous. Scale bar = 10 µm. Figures 76, 77. Internal valve view of Morphotype 2. Marginal fultoportulae are located on recessed costae, and have 3 satellite pores. Central fultoportula is present, situated among scattered areolae with domed cribra. Scale bars = 2, and 1 µm, respectively.