. Bulletin of the British Museum (Natural History), Geology. FROM GREAT BRITAIN AND FRANCE 271. Fig. 17. Leptodinium arcuatum (Klement). Tabulation and the archaeopyle formation (plate 3" is missing). Left, ventral view ; right, dorsal view. xc. 1280. The crests separate the four apical plates at the apex : plate 1' and 3' are smaller than plates 2' and 4'. Precingular plates are large, only plate 6" is somewhat reduced to accommodate intercalary plate ia, which is long. Five well-developed postcingular plates are present, plate 5" ' being smaller than the other postcingular pla
. Bulletin of the British Museum (Natural History), Geology. FROM GREAT BRITAIN AND FRANCE 271. Fig. 17. Leptodinium arcuatum (Klement). Tabulation and the archaeopyle formation (plate 3" is missing). Left, ventral view ; right, dorsal view. xc. 1280. The crests separate the four apical plates at the apex : plate 1' and 3' are smaller than plates 2' and 4'. Precingular plates are large, only plate 6" is somewhat reduced to accommodate intercalary plate ia, which is long. Five well-developed postcingular plates are present, plate 5" ' being smaller than the other postcingular plates. Posterior intercalary plate ip is placed between the plates 1" ' and 1" ". The antapex is occupied by a single antapical plate 1" ". The sulcus is long, extending between the apex and the antapex and broadening posteriorly. Remarks. The diagnosis is emended to include reference to the tabulation and the mode of archaeopyle formation, which were not mentioned by Klement. L. arcuatum was originally recorded from the Oxfordian of Germany by Klement (i960). Well-preserved specimens were observed infrequently in both English (Dorset) and French (Normandy and the Boulonnais) assemblages. Leptodinium clathratum (Cookson & Eisenack) Sarjeant, 1969 (PI. 11, fig- 8) 1960a Gonyaulax clathrata Cookson & Eisenack: 246-247, pi. 37, fig. 5 ; text-fig. 2. 1964 G. clathrata Cookson & Eisenack ; Downie & Sarjeant: 114. 1964 G. clathrata Cookson & Eisenack ; Eisenack: 339. 1964a G. clathrata Cookson & Eisenack ; Sarjeant, table 2. 1966 Gonyaulacysta clathrata (Cookson & Eisenack) ; Sarjeant, nomen nudum: 130. 1967b G. clathrata (Cookson & Eisenack) ; Vozzhennikova, table Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London :
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