. Bulletin of the British Museum (Natural History), Geology. 164 MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS The presence of an apical archaeopyle and the distinctive deeply furcate cingular processes make orientation of this species relatively easy. A number of well preserved specimens were studied and from the positions of the intratabular processes the reflected tabulation appeared to be 4', 6", 6c, 6'", ip, 3'". The test of the original dinoflagellate is tentatively reconstructed in the accompanying figure (Text-fig. 41). The reflected tabulation of S. longifurcatum is the s
. Bulletin of the British Museum (Natural History), Geology. 164 MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS The presence of an apical archaeopyle and the distinctive deeply furcate cingular processes make orientation of this species relatively easy. A number of well preserved specimens were studied and from the positions of the intratabular processes the reflected tabulation appeared to be 4', 6", 6c, 6'", ip, 3'". The test of the original dinoflagellate is tentatively reconstructed in the accompanying figure (Text-fig. 41). The reflected tabulation of S. longifurcatum is the same as in S. cribrotubiferum (Sarjeant, i960) ; however, the latter possesses characteristically perforate processes. Material (Figured). PI. 8, fig. 11, Geol. Surv. Colin. (1). Lower Chalk, Geological Survey Borehole, Fetcham Mill, Surrey at 840 feet depth. Upper Cretaceous (Cenomanian). Another specimen, PI. 8, fig. 7, , at 730 feet depth. Dimensions. Figured specimens : diameter of central body 32 by 37jx, length processes 20-24fjL. Range, lateral view : diameter of central body 30-47[x ; apical view : diameter of central body 36-50[jl ; length of processes 14-29PL. Mean diameter of archaeopyle, 20(x. Number of specimens measured, A"/ 3" 1 \ \ *" \ 5" 2<1 3e i—*L~T \ 2"'\ 3'" — —/~ 4'" / 5'"/. 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 : BM(NH)
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