Plate P22. 1, 2. Operculodinium echigoense Matsuoka 1983b; (2) courtesy of K. Matsuoka. Both 400x. 3. Operculodinium? eirikianum Head et al. 1989b. 700x. 4. Ovoidinium verrucosum (Cookson and Hughes 1964) Davey 1970. Ventral view (700x). 5, 6. Palaeocystodinium bulliforme Ioannides 1986. Both 250x. 7. "Palaeocystodinium striatogranulosum" Zevenboom and Santarelli in Zevenboom 1995 (considered an unpublished manuscript name by the originating authors). 300x. 8. Palaeohystrichophora infusorioides Deflandre 1935. Ventral view of dorsal surface (900x). 9, 10. Palaeoperidinium pyrophorum (Ehrenberg 1838 ex O. Wetzel 1933a) Sarjeant 1967b. Dorsal view of dorsal surface; (9) 400x; (10) 450x. 11–13. Palynodinium grallator Gocht 1970a; (11) with operculum (325x); (12) dorsal view of ventral surface (325x); (13) dorsal surface (325x). 14. Phthanoperidinium amoenum Drugg and Loeblich 1967. Dorsal view of dorsal surface (850x). 15. Phthanoperidinium distinctum Bujak 1994. Paratype (750x), courtesy of J.P. Bujak. 16–18. Pyxidinopsis fairhavenensis de Verteuil and Norris 1996a; (16, 17) same specimen, dorsal view of dorsal surface (825x); (18) same specimen as 16, optical section (825x), courtesy of L. de Verteuil. 19. Raetiaedinium truncigerum (Deflandre 1937b) Kirsch 1991. Dorsal view of dorsal surface (550x). 20. Raphidodinium fucatum Deflandre 1936b. 400x. 21. Renidinium rigidum Prince et al. 1999. 500x.

Plate P22. 1, 2. Operculodinium echigoense Matsuoka 1983b; (2) courtesy of K. Matsuoka. Both 400x. 3. Operculodinium? eirikianum Head et al. 1989b. 700x. 4. Ovoidinium verrucosum (Cookson and Hughes 1964) Davey 1970. Ventral view (700x). 5, 6. Palaeocystodinium bulliforme Ioannides 1986. Both 250x. 7. "Palaeocystodinium striatogranulosum" Zevenboom and Santarelli in Zevenboom 1995 (considered an unpublished manuscript name by the originating authors). 300x. 8. Palaeohystrichophora infusorioides Deflandre 1935. Ventral view of dorsal surface (900x). 9, 10. Palaeoperidinium pyrophorum (Ehrenberg 1838 ex O. Wetzel 1933a) Sarjeant 1967b. Dorsal view of dorsal surface; (9) 400x; (10) 450x. 11–13. Palynodinium grallator Gocht 1970a; (11) with operculum (325x); (12) dorsal view of ventral surface (325x); (13) dorsal surface (325x). 14. Phthanoperidinium amoenum Drugg and Loeblich 1967. Dorsal view of dorsal surface (850x). 15. Phthanoperidinium distinctum Bujak 1994. Paratype (750x), courtesy of J.P. Bujak. 16–18. Pyxidinopsis fairhavenensis de Verteuil and Norris 1996a; (16, 17) same specimen, dorsal view of dorsal surface (825x); (18) same specimen as 16, optical section (825x), courtesy of L. de Verteuil. 19. Raetiaedinium truncigerum (Deflandre 1937b) Kirsch 1991. Dorsal view of dorsal surface (550x). 20. Raphidodinium fucatum Deflandre 1936b. 400x. 21. Renidinium rigidum Prince et al. 1999. 500x.