. Bulletin of the British Museum (Natural History), Geology. 200 MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS HoLOTYPE. () slide ¥.51729(1). Speeton Clay, Shell West Heslerton Borehole at 39 metres depth, West Heslerton, Yorks. Lower Cretaceous (Middle Barremian). Dimensions. Holotype—overall length of enclosing body gofx, breadth 53-5(1, length of apical horn iSjx, of antapical horn 5|jl ; overall length of inner body 67-5jjl, breadth 38-5ji,. Range of dimensions ; overall length of enclosing body (1. Description. The holotype is enclosed in a spindle-shaped cloak of debris : in
. Bulletin of the British Museum (Natural History), Geology. 200 MESOZOIC AND CAINOZOIC DINOFLAGELLATE CYSTS HoLOTYPE. () slide ¥.51729(1). Speeton Clay, Shell West Heslerton Borehole at 39 metres depth, West Heslerton, Yorks. Lower Cretaceous (Middle Barremian). Dimensions. Holotype—overall length of enclosing body gofx, breadth 53-5(1, length of apical horn iSjx, of antapical horn 5|jl ; overall length of inner body 67-5jjl, breadth 38-5ji,. Range of dimensions ; overall length of enclosing body (1. Description. The holotype is enclosed in a spindle-shaped cloak of debris : in other specimens, the debris cloak appears less well formed. The outer membrane is spindle-shaped, with unequally developed horns. In the holotype, the apical horn tapers sharply to an acute point from about mid-length : this was not the case in other specimens, where the apical horn tapered more smoothly from base to tip. The inner body is of comparable shape, its apical horn always tapering smoothly from base to tip. No specimen seen shows a well-developed archaeopyle ; however, the holotype shows a slit, corresponding in position to a precingular opening, which may be an archaeopyle that has either incompletely opened or subsequently closed Fig. 51. Netrelytron trinetron sp. nov., showing the shell surrounded by the enclosing cloak of organic matter. x c. 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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