. Bulletin of the British Museum (Natural History), Geology. MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 229 plates i'" and 5'" bear multibranched linear or annular complexes. There are at least four cingular plates and some sulcal plates having linear complexes. The dorsal surface is convex, the ventral surface depressed. The processes on the ventral surface are closer to those of A. mediisettiformis than those of A. coronata, and can be simple or branched distally or proximally. A. cf. coronata resembles Systematophora in having process complexes on both ventral and dorsal surfaces
. Bulletin of the British Museum (Natural History), Geology. MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 229 plates i'" and 5'" bear multibranched linear or annular complexes. There are at least four cingular plates and some sulcal plates having linear complexes. The dorsal surface is convex, the ventral surface depressed. The processes on the ventral surface are closer to those of A. mediisettiformis than those of A. coronata, and can be simple or branched distally or proximally. A. cf. coronata resembles Systematophora in having process complexes on both ventral and dorsal surfaces. In the shape of the central body, position of the sulcal notch and predominance of soleate complexes however, it more closely approximates to Areoligera with which genus it must be included. Dimensions. Observed range ; diameter of central body 57-7110,, length of proces- ses up to 27(x. Occurrence. Eocene, London Clay ; Sheppey, Kent. Areoligera ci. medusettifortnis (O. Wetzel) PI- 25, fig. 4 Description. This has similar processes to A. medusettiformis and the same shape of central body. It differs, however, in the presence of process complexes on all the fields and not on the dorsal fields only. The precingular plates bear soleate complex- es, whilst plates i'" and 5'" have annular complexes. The complexes are unusual in being formed partly from simple processes, especially is this so with those processes nearest to the mid-ventral line. There is a well developed right antapical protuber- ance which is almost in line with the sulcal notch. Dimensions. Observed range : diameter of central body, 5o-67[x, length of processes up to 3^1. Number of specimens measured, 2. Occurrence. Eocene, London Clay ; Sheppey, 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)
Size: 1804px × 1385px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
