. Bulletin of the British Museum (Natural History), Geology. 192 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS she mentioned the presence of a second antapical plate: this plate (2"") was never observed in the Kimmeridgian specimens. According to the measurements quoted by Gorka, the Polish specimens from the Oxfordian are larger than the English and French Kimmeridgian specimens, with longer sutural spines. The attribution of these Polish specimens to the species C. calcaratum must, all in all, be considered very doubtful. Cryptarchaeodinium cf. calcaratum Plate 2, figure 3; text-fi
. Bulletin of the British Museum (Natural History), Geology. 192 KIMMERIDGIAN DINOFLAGELLATES & ACRITARCHS she mentioned the presence of a second antapical plate: this plate (2"") was never observed in the Kimmeridgian specimens. According to the measurements quoted by Gorka, the Polish specimens from the Oxfordian are larger than the English and French Kimmeridgian specimens, with longer sutural spines. The attribution of these Polish specimens to the species C. calcaratum must, all in all, be considered very doubtful. Cryptarchaeodinium cf. calcaratum Plate 2, figure 3; text-figure 3 Description : Shell spherical, with a small, blimt apical horn and rounded, dome- shaped antapex. Tabulation: 4', 6", 6c, 7'", 2p, ?ipv and 1"". Apical plates small; plates i' and 3' form the apical horn. The precingular plates are more or less constant in shape and size, the boundary between plates 5" and 6" not being clear. Cingulum equatorial, a laevorotatory spiral; cingular plates 3c and 4c are the largest and occupy the dorsal side. The postcingular plates are of variable shape and size: plates I'", 2'", and 7'" are relatively small and triangular, plate 4'" (the largest) is more or less square. Two posterior intercalary plates, ip and 2p, are present and placed on either side of plate ipv: the boundary between ip and ipv was not clear. Plate 2p is very small. The single antapical plate (i"") is convex and its greatest portion is positioned on the dorsal side of the cyst: this does not seem to be the result of distortion in compression. The sulcus is short, being very wide on the epitract but narrowing on the hypotract. On the plate boundaries, crests of irregularly spinous character rise up: some crest spines are briefly bifurcate. The shell surface is minutely granular. An archaeopyle was not Fig. 3. Cryptarchaeodinium cf. calcaratum Deflandre. General appearance, showing the tabulation: left,
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