. Bulletin of the British Museum (Natural History), Geology. MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 185 Wetzeliella {Wetzeliella) coleothrypta sp. nov. PL 18, figs. 8, 9 ; Text-fig. 47 Derivation of name. Greek, koleos, scabbard, sheath ; thrypto, break. Diagnosis. Thin walled periphragm characteristic pentagonal outline with each angle produced into horns, one apical, two lateral and two antapical ; left antapical horn generally reduced. Pericoel totally enclosing endophragm. Processes arising from periphragm, hollow, connecting with pericoel. Distally processes of individual simulate co
. Bulletin of the British Museum (Natural History), Geology. MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS 185 Wetzeliella {Wetzeliella) coleothrypta sp. nov. PL 18, figs. 8, 9 ; Text-fig. 47 Derivation of name. Greek, koleos, scabbard, sheath ; thrypto, break. Diagnosis. Thin walled periphragm characteristic pentagonal outline with each angle produced into horns, one apical, two lateral and two antapical ; left antapical horn generally reduced. Pericoel totally enclosing endophragm. Processes arising from periphragm, hollow, connecting with pericoel. Distally processes of individual simulate complex united by finely perforate membrane assuming outline of under- lying plate and extending over that plate as a replica of it. Processes commonly absent from pre- and postcingular plates on side lying nearest to cingulum. Reflec- ted tabulation of 4', 3a, 7", 5c, 5'", 2", 3-4S. HoLOTYPE. () sUde (3). London Clay ; Sheppey, Kent, sample Dimensions. Holotype : periphragm length i22(i. ; breadth iiO(x. Capsule length 69[i. ; breadth 61-5^.. Observed range : outer shell length 112-5-157^1 ; breadth 102-5-142(0,. Capsule length 66-io6[i, ; breadth 67-g7[x. Processes up to I5(i, long. Number of specimens measured, 6. Description. The periphragm of W. coleothrypta has an outline approaching W. similis on the one hand and W. articulata on the other. The right antapical horn is invariably longer than the left, which is often represented by a small protuberance. The apical horn has a pointed apex ; the lateral horns are indented distally due to the transverse cingulum crossing from the dorsal to the ventral surface at these two places. The slender, simple, or occasionally branched processes are intratabular,. 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 (Natura
Size: 1488px × 1680px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalhistory, bookcentury1900, bookcoll
