Plate P24. 1. Selenopemphix dionaeacysta Head et al. 1989b. Courtesy of M.J. Head. 750x. 2–4. Senoniasphaera inornata (Drugg 1970b) Stover and Evitt 1978; (2) ventral view of ventral surface (350x); (3, 4) dorsal surface (350x). 5. Senoniasphaera protrusa Clarke and Verdier 1967 (475x). 6, 7. Senoniasphaera rotundata Clarke and Verdier 1967; (6) dorsal view of dorsal surface (500x); (7) same specimen as 6, dorsal view, optical section (500x). 8, 9. Senoniasphaera rotundata subsp. alveolata Pearce et al. 2003; (8) dorsal surface (500x); (9) same specimen as 8, ventral surface (500x). 10. Spinidinium echinoideum (Cookson and Eisenack 1960a) Lentin and Williams 1976. Holotype (550x), from the L.E. Stover Collection. 11–14. Spinidinium macmurdoense (Wilson 1967a) Lentin and Williams 1976; (11) ventral view, optical section (400x); (12) dorsal view of dorsal surface (350x); (13) dorsal view, optical section (400x); (14) ventral view of ventral surface (350x). 15. Spiniferites porosus (Manum and Cookson 1964) Harland 1973. Right lateral view showing right lateral surface (325x). 16. Spiniferites ramosus subsp. maeandriformis (Corradini 1973) Lentin and Williams 1975. Left lateral view (425x). 17, 18. Spiniferites? velatus (Clarke and Verdier 1967) Stover and Evitt 1978. Both 375x. 19, 20. Spongodinium delitiense (Ehrenberg 1838) Deflandre 1936b; (19) oblique right view of right lateral surface (300x); (20) same specimen as 19, oblique right lateral view of left lateral surface (300x).

Plate P24. 1. Selenopemphix dionaeacysta Head et al. 1989b. Courtesy of M.J. Head. 750x. 2–4. Senoniasphaera inornata (Drugg 1970b) Stover and Evitt 1978; (2) ventral view of ventral surface (350x); (3, 4) dorsal surface (350x). 5. Senoniasphaera protrusa Clarke and Verdier 1967 (475x). 6, 7. Senoniasphaera rotundata Clarke and Verdier 1967; (6) dorsal view of dorsal surface (500x); (7) same specimen as 6, dorsal view, optical section (500x). 8, 9. Senoniasphaera rotundata subsp. alveolata Pearce et al. 2003; (8) dorsal surface (500x); (9) same specimen as 8, ventral surface (500x). 10. Spinidinium echinoideum (Cookson and Eisenack 1960a) Lentin and Williams 1976. Holotype (550x), from the L.E. Stover Collection. 11–14. Spinidinium macmurdoense (Wilson 1967a) Lentin and Williams 1976; (11) ventral view, optical section (400x); (12) dorsal view of dorsal surface (350x); (13) dorsal view, optical section (400x); (14) ventral view of ventral surface (350x). 15. Spiniferites porosus (Manum and Cookson 1964) Harland 1973. Right lateral view showing right lateral surface (325x). 16. Spiniferites ramosus subsp. maeandriformis (Corradini 1973) Lentin and Williams 1975. Left lateral view (425x). 17, 18. Spiniferites? velatus (Clarke and Verdier 1967) Stover and Evitt 1978. Both 375x. 19, 20. Spongodinium delitiense (Ehrenberg 1838) Deflandre 1936b; (19) oblique right view of right lateral surface (300x); (20) same specimen as 19, oblique right lateral view of left lateral surface (300x).