. Bulletin of the British Museum (Natural History), Geology. 26o DINOFLAGELLATE CYSTS. Fig. 12. Cyclonephelium spinetum n. sp. Holotype ; the apical archaeopyle is indicated by shading. ; W26A. Holotype. () Palaeont. slide Sample W26A, bed 9a, Bracklesham Beds, Lower Eocene, Whitecliff Bay, Isle of Wight, England. Dimensions. Holotype : cyst body (without operculum) 55 x 65 p ; length of processes up to 22 \x. Observed range : cyst body (without operculum) 40 x 55 /x to 58 x 68 fi; length of processes up to 36 /z. (n = 10). Remarks. The membranous processes are smooth


. Bulletin of the British Museum (Natural History), Geology. 26o DINOFLAGELLATE CYSTS. Fig. 12. Cyclonephelium spinetum n. sp. Holotype ; the apical archaeopyle is indicated by shading. ; W26A. Holotype. () Palaeont. slide Sample W26A, bed 9a, Bracklesham Beds, Lower Eocene, Whitecliff Bay, Isle of Wight, England. Dimensions. Holotype : cyst body (without operculum) 55 x 65 p ; length of processes up to 22 \x. Observed range : cyst body (without operculum) 40 x 55 /x to 58 x 68 fi; length of processes up to 36 /z. (n = 10). Remarks. The membranous processes are smooth or finely striated. They show considerable variation in breadth, varying from very broad and proximally closely spaced to narrow and proximally widely spaced. The overall form of the processes is broadly T-shaped. The acuminate spines projecting from the distal trabeculae show considerable variation in length, while the trabeculae themselves vary from broad and ribbon-like to slender strands. Cyclonephelium spinetum n. sp. is similar to C. laciniiforme Gerlach 1961 in overall form, but differs in having numerous acuminate spines projecting from the distal trabeculae. Acuminate spines are also developed in C. divaricatum Williams & Downie 1966c, but this species does not have the broad membranous processes which are typical of C. spinetum. Occurrence. Lower and Middle Eocene. Cyclonephelium vicinum n. sp. Fig. 13 ; PI. 8, figs 4-5 Derivation of Name. Latin, vicinus, near or neighbouring, with reference to the periphragm which remains close to the endophragm where the two layers are 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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